{ "modality": "CT", "exam_facts": { "scored_questions": 165, "pilot_questions": 30, "time_limit_minutes": 195, "spec_version": "ARRT CT Examination Content Specifications, Board approved July 2025, effective September 1, 2026 (current; replaced the 2022 specifications in effect through August 31, 2026). 195-minute test time and 30 pilot items per ARRT 2026 Postprimary Eligibility Pathway Handbook.", "source_url": "https://assets-us-01.kc-usercontent.com/406ac8c6-58e8-00b3-e3c1-0c312965deb2/7e8095ab-e424-496d-a5d4-d1e951d5783b/CT_Content_Specifications_2026.pdf" }, "content_categories": [ { "name": "Patient Care", "scored_questions": 21, "subcategories": [ { "name": "Patient Interactions and Management", "scored_questions": 21 } ] }, { "name": "Safety", "scored_questions": 21, "subcategories": [ { "name": "Radiation Safety and Dose", "scored_questions": 21 } ] }, { "name": "Image Production", "scored_questions": 52, "subcategories": [ { "name": "Image Formation", "scored_questions": 30 }, { "name": "Image Evaluation and Archiving", "scored_questions": 22 } ] }, { "name": "Procedures", "scored_questions": 71, "subcategories": [ { "name": "Head, Spine, and Musculoskeletal", "scored_questions": 25 }, { "name": "Neck and Chest", "scored_questions": 22 }, { "name": "Abdomen and Pelvis", "scored_questions": 24 } ] } ], "sections": [ { "id": "patient-care", "name": "Patient Care", "main_points": [ "Screen renal function before IV iodinated contrast; ACR guidance prefers eGFR over serum creatinine alone, and an eGFR below 30 mL/min/1.73 m² (or any acute kidney injury) marks the patient at highest risk for contrast-associated AKI.", "Per ACR guidance, patients taking metformin who have AKI or an eGFR below 30 should hold metformin at the time of contrast and for 48 hours afterward, restarting only after renal function is rechecked; those with eGFR ≥30 and no AKI do not need to stop.", "Use at least two patient identifiers and perform a time-out (correct patient, procedure, side/site) before invasive work such as CT-guided biopsy or drainage; check INR/PT, PTT and platelets beforehand to gauge bleeding risk.", "Screen females of childbearing age for pregnancy per facility policy (hCG when indicated); iodinated contrast in pregnancy is given only when essential, and ACR states breastfeeding does not need to be interrupted after iodinated contrast.", "Low-osmolality (LOCM) and iso-osmolality (IOCM) nonionic agents have largely replaced ionic high-osmolality contrast because they cause fewer adverse reactions.", "Reactions are graded mild (limited hives, nausea), moderate (diffuse hives, bronchospasm, facial edema) or severe (laryngeal edema, hypotensive shock, cardiopulmonary arrest); epinephrine is the first-line drug for anaphylaxis-type reactions.", "Hypotension with bradycardia points to a vasovagal reaction (treat with leg elevation, IV fluids, atropine if needed), whereas hypotension with tachycardia suggests an anaphylactoid reaction.", "Patients with a prior allergic-like reaction may be premedicated with corticosteroids plus an antihistamine (for example, prednisone 50 mg at 13, 7 and 1 hour before plus diphenhydramine 50 mg 1 hour before); premedication lowers but does not eliminate risk.", "For power injection, use a well-functioning 18–20 gauge antecubital catheter for high flow rates (around 4–5 mL/s) and only use central lines, PICCs or ports labeled power-injectable within their rated flow limits.", "If extravasation occurs, stop the injection, notify the radiologist, elevate the limb, apply compresses per policy, document volume/site, and escalate for signs of compartment syndrome (increasing pain, paresthesia, poor perfusion).", "Bolus tracking monitors an ROI in a target vessel and starts the scan once a preset HU threshold is reached; a timing bolus injects a small test dose to measure time-to-peak and set the scan delay.", "Dual-head injectors allow a saline chaser that pushes the contrast bolus centrally, lowering the contrast volume needed and reducing streak artifact from dense contrast in the arm and SVC veins." ], "vocabulary": [ { "term": "eGFR", "definition": "Estimated glomerular filtration rate, calculated from serum creatinine, age and sex; the preferred screening measure of kidney function before IV contrast." }, { "term": "Serum creatinine", "definition": "A muscle-metabolism waste product cleared by the kidneys; rising levels indicate reduced renal function (typical adult normal about 0.6–1.2 mg/dL)." }, { "term": "Contrast-associated AKI (CA-AKI)", "definition": "Acute kidney injury occurring after contrast administration, whether or not the contrast caused it." }, { "term": "Osmolality", "definition": "Concentration of particles in a contrast solution relative to plasma; lower osmolality is associated with fewer side effects." }, { "term": "Nonionic contrast", "definition": "Iodinated contrast whose molecules do not dissociate into charged particles in solution, giving lower osmolality and better tolerance." }, { "term": "Extravasation", "definition": "Leakage of injected contrast from the vein into surrounding soft tissue." }, { "term": "Anaphylactoid (allergic-like) reaction", "definition": "A contrast reaction resembling allergy, such as hives, bronchospasm or laryngeal edema, not necessarily IgE-mediated." }, { "term": "Vasovagal reaction", "definition": "A physiologic reaction producing hypotension with bradycardia, often with sweating and pallor." }, { "term": "Epinephrine", "definition": "Adrenergic drug that is first-line treatment for severe allergic-like reactions such as anaphylaxis or laryngeal edema." }, { "term": "Premedication", "definition": "Corticosteroid and antihistamine regimen given before contrast to reduce the risk of a repeat allergic-like reaction." }, { "term": "Bolus tracking", "definition": "Automated technique that repeatedly scans a monitoring level and triggers acquisition when an ROI reaches a set HU threshold." }, { "term": "Timing bolus", "definition": "A small test injection used to measure the time to peak vessel enhancement for setting the scan delay." }, { "term": "Saline chaser", "definition": "A bolus of saline injected immediately after contrast to push it centrally and reduce dense-contrast streak artifact." }, { "term": "Power-injectable PICC", "definition": "A peripherally inserted central catheter labeled for use with a power injector at a specified maximum flow rate and pressure." }, { "term": "Time-out", "definition": "A final pause before a procedure to confirm the correct patient, procedure and site with the team." }, { "term": "Intrathecal", "definition": "Into the subarachnoid space of the spinal canal, as for myelography contrast." }, { "term": "D-dimer", "definition": "A blood test for fibrin breakdown products; a negative result helps exclude pulmonary embolism or DVT." }, { "term": "Informed consent", "definition": "Patient agreement obtained after explaining a procedure's purpose, risks, benefits and alternatives." } ], "quiz": [ { "q": "According to ACR guidance, which laboratory value is preferred for screening kidney function before IV iodinated contrast?", "options": [ "Blood urea nitrogen alone", "eGFR", "Hemoglobin", "INR" ], "answer_index": 1, "explanation": "eGFR adjusts creatinine for age and sex and is the ACR-preferred screen; BUN alone is less reliable." }, { "q": "Which patient taking metformin should hold it at the time of IV iodinated contrast and for 48 hours afterward, per ACR guidance?", "options": [ "A patient with an eGFR of 75 and no AKI", "A patient with a stable eGFR of 45 and no AKI", "Any patient older than 60 regardless of renal function", "A patient with an eGFR of 25 mL/min/1.73 m²" ], "answer_index": 3, "explanation": "ACR recommends holding metformin for patients with AKI or eGFR below 30; those with eGFR ≥30 and no AKI need not stop." }, { "q": "Shortly after contrast injection a patient develops diffuse hives, wheezing and throat tightness. Which medication is first-line?", "options": [ "Epinephrine", "Atropine", "Furosemide", "Ondansetron" ], "answer_index": 0, "explanation": "Bronchospasm and laryngeal symptoms indicate a severe allergic-like reaction, for which epinephrine is first-line." }, { "q": "After contrast injection a patient is pale and sweaty with a blood pressure of 80/50 and a heart rate of 48. This most likely represents:", "options": [ "An anaphylactoid reaction", "Contrast-associated AKI", "A vasovagal reaction", "Contrast extravasation" ], "answer_index": 2, "explanation": "Hypotension with bradycardia is the hallmark of a vasovagal reaction; anaphylactoid hypotension is usually accompanied by tachycardia." }, { "q": "During a power injection the patient reports sudden pain and swelling at the IV site. What should the technologist do first?", "options": [ "Increase the flow rate to finish quickly", "Massage the site firmly", "Stop the injection immediately", "Apply a tourniquet above the site" ], "answer_index": 2, "explanation": "Stopping the injection limits the extravasated volume; the radiologist is then notified and the limb elevated and documented." }, { "q": "Which IV access is most appropriate for a CT angiogram planned at 5 mL/s?", "options": [ "A 20-gauge catheter in an antecubital vein", "A 24-gauge catheter in a hand vein", "A central line not labeled for power injection", "A butterfly needle in the wrist" ], "answer_index": 0, "explanation": "High flow rates need a large-bore, well-functioning antecubital catheter; small-gauge or non-power-rated devices risk rupture or extravasation." }, { "q": "With bolus tracking, what starts the diagnostic acquisition?", "options": [ "A fixed 120-second delay after injection", "The patient's heart rate dropping below 60 bpm", "Completion of the saline chaser", "The monitoring ROI reaching a preset HU threshold" ], "answer_index": 3, "explanation": "Bolus tracking repeatedly samples a vessel ROI and triggers once enhancement reaches the chosen threshold." }, { "q": "A key benefit of a saline chaser delivered by a dual-head injector is that it:", "options": [ "Increases the iodine concentration of the contrast", "Reduces the contrast volume needed and streak artifact from dense venous contrast", "Directly lowers the radiation dose", "Eliminates the need for IV access" ], "answer_index": 1, "explanation": "Saline pushes the tail of the bolus into circulation, so less contrast is needed and dense contrast does not linger in the arm/SVC veins." }, { "q": "Bowel perforation is suspected. Which oral contrast is most appropriate?", "options": [ "Water-soluble iodinated contrast", "Barium sulfate suspension", "High-density barium paste", "Effervescent granules only" ], "answer_index": 0, "explanation": "Barium leaking into the peritoneum can cause serious peritonitis, so water-soluble iodinated contrast is used when perforation is a concern." }, { "q": "According to ACR guidance, a breastfeeding mother receiving IV iodinated contrast:", "options": [ "Must stop breastfeeding for 7 days", "Must pump and discard milk for 72 hours", "Does not need to interrupt breastfeeding", "Should not receive iodinated contrast at all" ], "answer_index": 2, "explanation": "Very little contrast reaches breast milk and less is absorbed by the infant; ACR states interruption is not necessary, though the mother may choose to abstain briefly." }, { "q": "The primary purpose of a time-out before a CT-guided biopsy is to:", "options": [ "Allow the contrast to reach equilibrium", "Confirm the correct patient, procedure and site", "Calibrate the detectors", "Give the patient time to sign the insurance form" ], "answer_index": 1, "explanation": "The time-out is a universal-protocol safety step that prevents wrong-patient, wrong-procedure and wrong-site errors." }, { "q": "Which laboratory value is most relevant for assessing bleeding risk before a CT-guided biopsy?", "options": [ "eGFR", "D-dimer", "hCG", "INR" ], "answer_index": 3, "explanation": "INR/PT (with PTT and platelets) reflects clotting ability; eGFR relates to contrast safety and hCG to pregnancy." } ], "bank": [ { "q": "An anuric patient on maintenance hemodialysis needs a contrast-enhanced CT. Per current ACR guidance, the patient:", "options": [ "Should always have the exam changed to a noncontrast CT instead", "Can receive contrast; dialysis is not started or rescheduled solely for it", "Must be dialyzed within 1 hour after the injection to remove the contrast", "Should receive half the usual dose plus a steroid premedication regimen" ], "answer_index": 1, "explanation": "ACR guidance states acute dialysis should not be initiated and the dialysis schedule should not be changed solely because iodinated contrast was given. Anuric dialysis patients have no residual function left to protect.", "subcategory": "Patient Interactions and Management" }, { "q": "A CT angiogram is programmed at 4 mL/s for an injection duration of 25 seconds. How much contrast will be delivered?", "options": [ "75 mL", "29 mL", "100 mL", "125 mL" ], "answer_index": 2, "explanation": "Volume equals flow rate multiplied by injection duration: 4 mL/s × 25 s = 100 mL.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient receives 80 mL of a contrast agent containing 350 mg of iodine per mL. What total iodine dose was given?", "options": [ "2.8 g", "28 g", "35 g", "43.75 g" ], "answer_index": 1, "explanation": "80 mL × 350 mgI/mL = 28,000 mg, or 28 g of iodine.", "subcategory": "Patient Interactions and Management" }, { "q": "Using a weight-based dose of 2 mL/kg, how much IV contrast should an 18 kg child receive?", "options": [ "18 mL", "36 mL", "72 mL", "9 mL" ], "answer_index": 1, "explanation": "18 kg × 2 mL/kg = 36 mL; pediatric contrast is typically dosed by weight rather than as a fixed adult volume.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient with a history of pheochromocytoma is scheduled for a CT with IV nonionic iodinated contrast. According to the ACR, the technologist should:", "options": [ "Proceed; this history alone does not call for premedication or restriction", "Use a high-osmolality ionic agent to lower the risk", "Give a corticosteroid premedication regimen before the injection", "Cancel IV contrast because it reliably triggers hypertensive crisis" ], "answer_index": 0, "explanation": "The ACR notes no evidence that modern IV iodinated contrast increases the risk of hypertensive crisis in pheochromocytoma, so premedicating or restricting on that basis alone is not recommended.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient with a known high risk of aspiration needs oral contrast for an abdominal CT. Which oral agent is most important to avoid?", "options": [ "Dilute barium sulfate suspension given in small sips", "A dilute low-osmolality nonionic iodinated contrast agent", "Plain water used as a neutral oral contrast agent", "A high-osmolality ionic iodinated agent such as diatrizoate" ], "answer_index": 3, "explanation": "Aspirated hyperosmolar oral contrast draws fluid into the lungs and can cause chemical pneumonitis or pulmonary edema; dilute barium or low-osmolality agents are safer when aspiration is likely.", "subcategory": "Patient Interactions and Management" }, { "q": "Warming iodinated contrast to body temperature before a power injection mainly:", "options": [ "Speeds renal excretion of the contrast", "Lowers its viscosity and injection pressure", "Prevents allergic-like contrast reactions", "Raises the iodine concentration of the agent" ], "answer_index": 1, "explanation": "Warming contrast to about 37 °C reduces viscosity, which lowers injection pressure and may reduce extravasation risk, especially with higher-concentration agents.", "subcategory": "Patient Interactions and Management" }, { "q": "After scanning a patient on contact precautions for Clostridioides difficile, which hand hygiene is most appropriate?", "options": [ "An alcohol-based hand rub alone", "Washing with soap and water", "Wiping hands with a disinfectant equipment wipe", "Changing gloves without hand hygiene" ], "answer_index": 1, "explanation": "Alcohol does not reliably kill C. difficile spores, so mechanical washing with soap and water is recommended, along with a sporicidal cleaner for surfaces.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient with a chest tube is transferred to the CT table. The drainage unit should be:", "options": [ "Kept upright below chest level and not clamped", "Clamped for the entire exam to prevent air leaks", "Raised above chest level to help speed drainage", "Placed on the patient's abdomen during the scan" ], "answer_index": 0, "explanation": "Keeping the unit upright and below the chest prevents backflow into the pleural space; tubes are not clamped unless ordered, because clamping can cause a tension pneumothorax.", "subcategory": "Patient Interactions and Management" }, { "q": "When choosing a site for IV placement before a contrast CT, which arm should be avoided?", "options": [ "The nondominant arm's antecubital vein", "The forearm on the side opposite the injury", "The arm with the most palpable vein", "The arm with a hemodialysis arteriovenous fistula" ], "answer_index": 3, "explanation": "An AV fistula or graft must be protected and is not used for routine venipuncture or power injection; the arm on the side of a mastectomy with node dissection is also usually avoided.", "subcategory": "Patient Interactions and Management" }, { "q": "An unconscious trauma patient with no family present needs an emergent contrast-enhanced CT. Consent for the exam is:", "options": [ "Required in writing before any scanning can occur", "Oral consent obtained from another patient's family", "Implied consent under the emergency exception", "Written informed consent signed by the technologist" ], "answer_index": 2, "explanation": "In an emergency where the patient cannot consent and no representative is available, consent is implied because a reasonable person would agree to life-saving care.", "subcategory": "Patient Interactions and Management" }, { "q": "During a CT-guided lung biopsy under moderate sedation, the pulse oximeter falls from 97% to 86%. The technologist's best first action is to:", "options": [ "Stop, assess the airway, notify the radiologist and give oxygen", "Document the reading and recheck it after the exam ends", "Give additional sedative so the patient stays still", "Continue scanning, since the probe is probably loose" ], "answer_index": 0, "explanation": "An SpO2 in the mid-80s indicates hypoxemia; sedation, pneumothorax or airway compromise must be addressed immediately, not after the procedure.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient on the CT table suddenly becomes unresponsive, and the monitor shows a chaotic, irregular waveform with no identifiable QRS complexes. This rhythm is most likely:", "options": [ "First-degree heart block", "Ventricular fibrillation", "Sinus bradycardia", "Atrial fibrillation" ], "answer_index": 1, "explanation": "Ventricular fibrillation produces disorganized waves without QRS complexes and no pulse; call a code, start CPR and defibrillate as soon as possible.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient received oral lorazepam before a CT for claustrophobia. Post-procedure instructions should include that the patient:", "options": [ "Must not drive and should leave with a responsible adult", "Should drink extra water to flush out the sedative", "May drive home after 15 minutes of observation in the department", "Needs to repeat the dose before leaving the department" ], "answer_index": 0, "explanation": "Anxiolytics such as lorazepam impair alertness for hours, so the patient needs a driver and should avoid driving or operating machinery.", "subcategory": "Patient Interactions and Management" }, { "q": "After IV contrast, a patient develops mild wheezing with stable vital signs and normal oxygen saturation. Which treatment is typically first-line?", "options": [ "IV furosemide (a loop diuretic)", "IV atropine given slowly", "Inhaled albuterol (a beta-agonist)", "IV diphenhydramine as the only drug" ], "answer_index": 2, "explanation": "Mild bronchospasm is treated with oxygen as needed and an inhaled beta-agonist; epinephrine is added if it is moderate or severe or does not respond.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient scheduled for radioactive iodine thyroid therapy next week is ordered for a contrast-enhanced CT. The technologist should check with the radiologist because:", "options": [ "Radioiodine therapy is a contraindication to any CT", "Only oral barium would interfere with the therapy", "Iodinated contrast enhances radioiodine uptake to toxic levels", "Iodinated contrast can reduce thyroid uptake of radioiodine for weeks" ], "answer_index": 3, "explanation": "The iodine load from contrast saturates the thyroid and can block radioiodine uptake for several weeks, so the timing of the two procedures must be coordinated.", "subcategory": "Patient Interactions and Management" }, { "q": "Which method of verifying identity before an outpatient CT meets Joint Commission patient-identification goals?", "options": [ "Asking \"Are you Mr. Smith?\" and waiting for a yes", "Matching the room number to the requisition form", "Checking that the name on the order looks correct", "Having the patient state full name and date of birth" ], "answer_index": 3, "explanation": "Two patient-specific identifiers, such as name and date of birth stated by the patient, are required; room numbers and yes/no questions are not acceptable.", "subcategory": "Patient Interactions and Management" }, { "q": "Minutes after IV contrast, a patient becomes lightheaded; there are no hives, the pressure is 76/40 and the pulse is 128. Initial management is to:", "options": [ "Give IV atropine 0.6 mg and observe for a heart rate response", "Sit the patient upright and encourage oral fluids before discharge", "Give oral diphenhydramine and recheck vital signs in an hour", "Elevate the legs, give oxygen and IV fluids, and prepare epinephrine" ], "answer_index": 3, "explanation": "Hypotension with tachycardia suggests an anaphylactoid reaction; leg elevation, oxygen and rapid IV fluids come first, with epinephrine if it persists.", "subcategory": "Patient Interactions and Management" }, { "q": "While removing a peripheral IV after a CT, a technologist sustains a needlestick. The first step is to:", "options": [ "Squeeze and bleed the wound, then apply bleach", "Wash the site with soap and water, then report it", "Finish the next patient, then tell a supervisor", "Apply an antibiotic ointment and a bandage only" ], "answer_index": 1, "explanation": "Exposed skin is washed promptly with soap and water and the exposure reported immediately so post-exposure evaluation can begin.", "subcategory": "Patient Interactions and Management" }, { "q": "Per current ACR-NKF guidance, which outpatient is a candidate for prophylactic IV volume expansion before IV iodinated contrast?", "options": [ "A diabetic patient with an eGFR of 55 mL/min/1.73 m²", "A patient taking metformin with an eGFR of 42 mL/min/1.73 m²", "An anuric patient who receives maintenance hemodialysis", "A patient not on dialysis with an eGFR of 24 mL/min/1.73 m²" ], "answer_index": 3, "explanation": "Prophylaxis is indicated for an eGFR below 30 (or AKI) in patients not on dialysis; it is not needed at an eGFR of 30 or higher.", "subcategory": "Patient Interactions and Management" }, { "q": "Two days after a contrast-enhanced CT, a patient calls to report an itchy red rash on the trunk with no breathing problems. This is most consistent with:", "options": [ "Contrast-associated acute kidney injury", "A delayed cutaneous reaction to the contrast", "A late anaphylactoid airway reaction", "Contrast-induced thyroid storm" ], "answer_index": 1, "explanation": "Delayed skin reactions such as maculopapular rashes can appear hours to a week after iodinated contrast and are usually self-limited.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient with suspected active pulmonary tuberculosis needs a chest CT. Staff in close contact with the patient should wear:", "options": [ "A fit-tested N95 respirator", "A surgical mask and gloves only", "A gown and gloves without a mask", "Eye protection and a cloth mask" ], "answer_index": 0, "explanation": "Tuberculosis is spread by the airborne route, so airborne precautions with a fit-tested N95 (or higher) respirator are required.", "subcategory": "Patient Interactions and Management" }, { "q": "A pregnant patient with suspected pulmonary embolism needs a CT pulmonary angiogram. Regarding iodinated contrast, the ACR states that it:", "options": [ "May be given when needed, as no fetal harm has been shown", "Is contraindicated in every trimester of pregnancy", "Requires the 13-hour steroid premedication regimen", "Must be withheld until after the first trimester ends" ], "answer_index": 0, "explanation": "The ACR does not withhold iodinated contrast from pregnant patients when it is needed for diagnosis; newborn thyroid function is screened routinely.", "subcategory": "Patient Interactions and Management" }, { "q": "Which resting respiratory rate is within the normal range for a healthy adult?", "options": [ "16 breaths per minute", "6 breaths per minute", "28 breaths per minute", "34 breaths per minute" ], "answer_index": 0, "explanation": "The normal adult resting respiratory rate is roughly 12 to 20 breaths per minute.", "subcategory": "Patient Interactions and Management" }, { "q": "For an adult having an anaphylactic-type reaction to contrast, the ACR-listed intramuscular epinephrine dose is:", "options": [ "3 mg of the 0.1 mg/mL solution into the deltoid muscle", "0.3 mg of the 1 mg/mL solution into the anterolateral thigh", "0.3 mg of the 0.1 mg/mL solution given by rapid IV push", "1 mg of the 1 mg/mL solution into the gluteal muscle" ], "answer_index": 1, "explanation": "Adult IM epinephrine is 0.3 mg of 1 mg/mL (1:1,000) solution, or a 0.3 mg autoinjector, given in the anterolateral thigh.", "subcategory": "Patient Interactions and Management" }, { "q": "Per the ACR, the standard oral premedication regimen for an elective outpatient with a prior allergic-like reaction to iodinated contrast gives prednisone 50 mg at:", "options": [ "13, 7 and 1 hour before contrast, plus diphenhydramine 1 hour before", "24, 12 and 2 hours before contrast, plus ranitidine 1 hour before", "12 and 2 hours before contrast, plus diphenhydramine after the scan", "1 hour before contrast only, plus diphenhydramine 13 hours before" ], "answer_index": 0, "explanation": "The ACR 13-hour regimen is prednisone 50 mg orally at 13, 7 and 1 hour before injection with diphenhydramine 50 mg 1 hour before.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient with right-sided weakness after a stroke is moving from a wheelchair to the CT table. The wheelchair should be placed so the patient transfers:", "options": [ "Toward the right, affected side", "Backward with the brakes released", "Toward the left, unaffected side", "Feet first with the footrests down" ], "answer_index": 2, "explanation": "Patients with one-sided weakness transfer toward their strong side, with the wheelchair locked and footrests moved out of the way.", "subcategory": "Patient Interactions and Management" }, { "q": "A patient's PICC line is not labeled as power-injectable. A contrast CT is ordered at 3 mL/s. The technologist should:", "options": [ "Power inject at 3 mL/s after raising the injector pressure limit", "Power inject if a hand saline flush meets no resistance first", "Avoid power injection through it and place a suitable peripheral IV", "Power inject through it at a reduced rate of about 2.5 mL/s" ], "answer_index": 2, "explanation": "Only catheters labeled power-injectable may be used with a power injector; a non-power PICC can rupture, so alternative access is needed.", "subcategory": "Patient Interactions and Management" }, { "q": "After a 90 mL contrast extravasation in the forearm, which finding calls for prompt surgical consultation?", "options": [ "Mild swelling that is improving with arm elevation", "Coolness of the skin directly over the injection site", "Increasing pain, skin blistering or decreased capillary refill", "Slight tenderness that resolves within about an hour" ], "answer_index": 2, "explanation": "Progressive pain, blistering, altered perfusion or paresthesias suggest compartment syndrome or skin injury and need surgical evaluation.", "subcategory": "Patient Interactions and Management" }, { "q": "Immediately after IV contrast, a patient reports warmth, a metallic taste and mild nausea. Vital signs are normal. The best response is to:", "options": [ "Give IM epinephrine and activate the code team", "Reassure and observe, since these are physiologic effects", "Administer IV diphenhydramine before continuing", "Stop the scan and begin IV corticosteroids" ], "answer_index": 1, "explanation": "Warmth, metallic taste and transient mild nausea are common physiologic responses to contrast and need only reassurance and observation.", "subcategory": "Patient Interactions and Management" } ] }, { "id": "safety", "name": "Safety", "main_points": [ "SI units are primary on the ARRT CT exam: absorbed dose and CTDI are in milligray (mGy), effective dose is in millisievert (mSv), and DLP is in mGy·cm.", "CTDIvol is the scanner's average radiation output within the scan volume for a given protocol (CTDIw divided by pitch), measured in 16 cm head or 32 cm body phantoms; it is an index, not the patient's actual dose.", "DLP equals CTDIvol multiplied by scan length, so extending coverage raises DLP even when CTDIvol is unchanged; effective dose can be estimated as DLP × a region-specific conversion (k) factor.", "Dose is directly proportional to mAs, while image noise is inversely proportional to the square root of mAs, so doubling mAs doubles dose but reduces noise by only about 29%.", "Raising kVp increases dose and beam penetration but lowers subject contrast; lowering kVp moves photon energies closer to iodine's K-edge (33 keV), boosting iodine contrast for CTA and pediatric studies.", "Pitch is table travel per rotation divided by total beam collimation; at constant mA a higher pitch lowers dose, though scanners using effective mAs adjust tube current to hold dose and noise constant.", "Automatic tube current modulation adapts mA by angle and z-axis using the scout; centering the patient at isocenter is essential, because miscentering mismatches the bowtie filter and distorts modulation, raising dose or noise.", "Over-ranging is the extra exposure at the start and end of a helical scan needed for interpolation; over-beaming is penumbra exposure beyond the active detectors and is proportionally worse with narrow collimation.", "Iterative reconstruction lowers image noise relative to filtered backprojection, allowing dose reduction while maintaining diagnostic quality.", "Photoelectric absorption dominates at low energies and in high-atomic-number materials (bone, iodine) and drives image contrast; Compton scatter dominates in soft tissue at CT energies and is the main source of staff exposure.", "Dose notification values warn before scanning when a planned series exceeds a preset CTDIvol/DLP; dose alert values warn when the accumulated dose for the exam would exceed a higher threshold, and overrides must be documented.", "Protect personnel with time, distance and shielding: intensity follows the inverse square law, the scan room is access-controlled, and anyone who must stay in the room wears a lead apron; record dose and report scanning errors per facility adverse-event policy." ], "vocabulary": [ { "term": "Absorbed dose", "definition": "Energy deposited per unit mass of tissue, measured in gray (Gy) or milligray (mGy)." }, { "term": "Effective dose", "definition": "A whole-body risk estimate that weights organ doses by radiosensitivity, measured in sievert (Sv) or millisievert (mSv)." }, { "term": "CTDIvol", "definition": "Volume CT dose index: average dose in a standard phantom for a protocol, adjusted for pitch, in mGy." }, { "term": "CTDIw", "definition": "Weighted CTDI combining center and peripheral phantom measurements to represent the average dose in a slice." }, { "term": "Dose-length product (DLP)", "definition": "CTDIvol multiplied by scan length, reflecting total scanner output for the exam, in mGy·cm." }, { "term": "Pitch", "definition": "Table movement per gantry rotation divided by the total nominal beam collimation." }, { "term": "Automatic tube current modulation (ATCM)", "definition": "Software that varies mA by projection angle and z-axis position to match patient attenuation." }, { "term": "Isocenter", "definition": "The center of gantry rotation where the patient should be positioned for correct bowtie filtration and dose modulation." }, { "term": "Over-ranging", "definition": "Additional rotations at the ends of a helical scan, outside the planned range, needed for data interpolation." }, { "term": "Over-beaming", "definition": "Radiation in the beam penumbra that falls outside the active detector rows and does not contribute to the image." }, { "term": "Bowtie filter", "definition": "A shaped beam filter that is thicker at the edges to match patient shape, reducing peripheral dose and equalizing detector signal." }, { "term": "Bremsstrahlung radiation", "definition": "X-rays produced when electrons are decelerated by the target nucleus; most of the CT beam." }, { "term": "Characteristic radiation", "definition": "X-rays emitted when an outer-shell electron fills an inner-shell vacancy in the target atom." }, { "term": "Photoelectric absorption", "definition": "Interaction in which a photon is fully absorbed by ejecting an inner-shell electron; increases with atomic number and lower energy." }, { "term": "Compton scatter", "definition": "Interaction in which a photon ejects an outer-shell electron and continues at lower energy in a new direction." }, { "term": "Inverse square law", "definition": "Radiation intensity varies inversely with the square of the distance from the source." }, { "term": "ALARA", "definition": "As low as reasonably achievable: the principle of using the least radiation that still gives a diagnostic result." }, { "term": "Dose notification value", "definition": "A per-series threshold that warns the technologist before scanning when the planned dose index exceeds it." }, { "term": "Dose alert value", "definition": "A cumulative threshold that warns when the total dose for an exam would exceed it, requiring justification to proceed." } ], "quiz": [ { "q": "Which dose descriptor is calculated by multiplying CTDIvol by the scan length?", "options": [ "Effective dose", "CTDIw", "Size-specific dose estimate", "Dose-length product (DLP)" ], "answer_index": 3, "explanation": "DLP = CTDIvol × scan length and is expressed in mGy·cm." }, { "q": "A chest CT has a CTDIvol of 10 mGy and a scan length of 40 cm. What is the DLP?", "options": [ "4 mGy·cm", "400 mGy·cm", "50 mGy·cm", "4,000 mGy·cm" ], "answer_index": 1, "explanation": "10 mGy × 40 cm = 400 mGy·cm." }, { "q": "If mAs is doubled with all other factors unchanged, how are dose and image noise affected?", "options": [ "Dose doubles; noise is halved", "Dose quadruples; noise decreases by about 29%", "Dose doubles; noise decreases by about 29%", "Dose is unchanged; noise is halved" ], "answer_index": 2, "explanation": "Dose is proportional to mAs, while noise falls with the square root of mAs (1/√2 ≈ 0.71)." }, { "q": "The table moves 60 mm per rotation with a total beam collimation of 40 mm. What is the pitch?", "options": [ "1.5", "0.67", "1.0", "2.4" ], "answer_index": 0, "explanation": "Pitch = table travel per rotation ÷ total collimation = 60 ÷ 40 = 1.5." }, { "q": "Which photon interaction is the dominant source of scatter in soft tissue at diagnostic CT energies?", "options": [ "Photoelectric absorption", "Compton scatter", "Coherent scatter", "Pair production" ], "answer_index": 1, "explanation": "Compton interactions predominate in soft tissue at CT energies and create most scatter, the main staff exposure source." }, { "q": "Lowering kVp from 120 to 80 for a CT angiogram increases vessel enhancement mainly because:", "options": [ "Compton scatter increases", "The x-ray tube produces more characteristic radiation", "Pitch automatically decreases", "Photoelectric absorption by iodine increases at lower photon energies" ], "answer_index": 3, "explanation": "Lower-energy photons are closer to iodine's 33 keV K-edge, so photoelectric absorption and iodine contrast increase." }, { "q": "A patient is positioned well below gantry isocenter for an abdominal CT with tube current modulation. The most likely result is:", "options": [ "Increased dose and/or noise from bowtie mismatch and inaccurate modulation", "Improved spatial resolution with no dose change", "Lower dose with no effect on image quality", "Elimination of beam-hardening artifact" ], "answer_index": 0, "explanation": "Miscentering misaligns the bowtie filter and distorts the scout-based mA calculation, raising dose, noise or both." }, { "q": "The extra exposure at the beginning and end of a helical acquisition, needed for interpolation, is called:", "options": [ "Over-beaming", "Heel effect", "Over-ranging", "Backprojection" ], "answer_index": 2, "explanation": "Over-ranging adds rotations outside the planned range; adaptive collimation can reduce it." }, { "q": "Which quantity, measured in mSv, accounts for the varying radiosensitivity of tissues?", "options": [ "Absorbed dose", "CTDIvol", "Effective dose", "Exposure" ], "answer_index": 2, "explanation": "Effective dose weights organ doses by tissue sensitivity to estimate whole-body stochastic risk." }, { "q": "How does a CT dose alert value differ from a dose notification value?", "options": [ "It applies to the accumulated dose for the exam rather than a single series", "It is expressed in mSv instead of mGy", "It only applies to pediatric patients", "It is set by the patient's physician for each order" ], "answer_index": 0, "explanation": "Notification values check each planned series; alert values check the cumulative dose and require documented justification to proceed." }, { "q": "A technologist moves from 1 m to 2 m from a radiation source. The exposure intensity becomes:", "options": [ "One-half as much", "Twice as much", "Unchanged", "One-fourth as much" ], "answer_index": 3, "explanation": "Per the inverse square law, doubling distance reduces intensity by a factor of four." }, { "q": "Most x-ray photons produced at the tungsten anode of a CT tube are:", "options": [ "Characteristic", "Bremsstrahlung", "Compton", "Annihilation" ], "answer_index": 1, "explanation": "Bremsstrahlung (braking) radiation makes up the large majority of the polyenergetic beam." } ], "bank": [ { "q": "In a CT x-ray tube, electrons are produced at the cathode filament by:", "options": [ "Compton scattering", "Thermionic emission", "The photoelectric effect", "Characteristic emission" ], "answer_index": 1, "explanation": "Heating the filament boils off electrons (thermionic emission); the tube current (mA) controls how many are produced.", "subcategory": "Radiation Safety and Dose" }, { "q": "Increasing kVp from 100 to 120 with all other factors constant will:", "options": [ "Increase both beam quality and beam quantity", "Increase beam quantity but not beam quality", "Increase beam quality but decrease quantity", "Decrease both beam quality and beam quantity" ], "answer_index": 0, "explanation": "Higher kVp raises the maximum and mean photon energy (quality) and also produces more photons (quantity), which is why dose rises with kVp.", "subcategory": "Radiation Safety and Dose" }, { "q": "Compared with lower-energy x-ray photons, higher-energy photons have:", "options": [ "Longer wavelength and higher frequency", "Shorter wavelength and lower frequency", "The same wavelength but greater speed", "Shorter wavelength and higher frequency" ], "answer_index": 3, "explanation": "Photon energy is directly proportional to frequency and inversely proportional to wavelength; all x-rays travel at the speed of light.", "subcategory": "Radiation Safety and Dose" }, { "q": "Which photon interaction changes the photon's direction without ionizing the atom and contributes little at CT energies?", "options": [ "Compton (incoherent) scatter", "Pair production", "Photoelectric absorption", "Coherent (classical) scatter" ], "answer_index": 3, "explanation": "In coherent scatter, the photon is redirected with no loss of energy and no ionization; it accounts for only a small share of interactions at CT energies.", "subcategory": "Radiation Safety and Dose" }, { "q": "Added beam filtration in a CT system reduces patient dose mainly by:", "options": [ "Absorbing high-energy photons that cause most scatter", "Narrowing the beam collimation along the z-axis", "Lowering the tube current automatically during the scan", "Absorbing low-energy photons that would add dose but not image" ], "answer_index": 3, "explanation": "Filtration (including the bowtie) hardens the beam by absorbing soft photons that would only add skin and surface dose.", "subcategory": "Radiation Safety and Dose" }, { "q": "A protocol has a CTDIw of 20 mGy and is scanned at a pitch of 1.25. What is the CTDIvol?", "options": [ "16 mGy", "20 mGy", "25 mGy", "12.5 mGy" ], "answer_index": 0, "explanation": "CTDIvol = CTDIw ÷ pitch = 20 ÷ 1.25 = 16 mGy.", "subcategory": "Radiation Safety and Dose" }, { "q": "An abdomen/pelvis CT has a DLP of 600 mGy·cm. Using a conversion factor (k) of 0.015 mSv/(mGy·cm), the estimated effective dose is:", "options": [ "90 mSv", "9 mSv", "0.9 mSv", "40 mSv" ], "answer_index": 1, "explanation": "Effective dose ≈ DLP × k = 600 × 0.015 = 9 mSv; this is a population-based estimate, not an individual's dose.", "subcategory": "Radiation Safety and Dose" }, { "q": "For a small, thin adult scanned with a body protocol, how does the size-specific dose estimate (SSDE) compare with the CTDIvol displayed for the 32 cm phantom?", "options": [ "The SSDE is higher than the displayed CTDIvol", "The SSDE cannot be calculated for adults", "The SSDE is lower than the displayed CTDIvol", "The two values are always identical" ], "answer_index": 0, "explanation": "Smaller patients absorb more of the beam per unit output than the 32 cm phantom, so SSDE, which corrects CTDIvol for patient size, exceeds the displayed CTDIvol.", "subcategory": "Radiation Safety and Dose" }, { "q": "Current AAPM and ACR guidance on placing lead shields within the scanned anatomy during a CT exam that uses tube current modulation is best summarized as:", "options": [ "Required over the gonads for all patients of reproductive age", "Generally discouraged, since shields can raise dose or cause artifacts", "Required over the thyroid for every routine head CT exam", "Recommended for all patients, provided it is placed before the scout" ], "answer_index": 1, "explanation": "In-field shielding can cause streaks and, if present on the scout, can drive automatic exposure control to increase tube current; professional bodies now discourage routine use.", "subcategory": "Radiation Safety and Dose" }, { "q": "A pregnant trauma patient needs a noncontrast head CT. Regarding fetal dose, the technologist should know that:", "options": [ "It is high enough that a pelvic shield must replace other dose reduction", "The fetus receives about the same dose as the brain", "It is very low, because the fetus is outside the primary beam", "The exam is contraindicated during the first trimester" ], "answer_index": 2, "explanation": "Only minimal internal scatter reaches the fetus during head CT; a medically indicated exam should proceed, using standard dose optimization.", "subcategory": "Radiation Safety and Dose" }, { "q": "Which step most directly prevents an unnecessary repeat exposure on a chest CT?", "options": [ "Selecting the largest available scan FOV", "Raising the kVp to shorten the scan time", "Practicing the breath-hold instructions first", "Lowering the table so the chest is below isocenter" ], "answer_index": 2, "explanation": "Respiratory motion is a leading cause of repeat scans; clear communication and a practice breath-hold help the patient comply on the first attempt.", "subcategory": "Radiation Safety and Dose" }, { "q": "Compared with a wide beam, using a very narrow total beam collimation on a multidetector scanner tends to:", "options": [ "Remove the need for a bowtie filter on the scanner", "Lower patient dose for the same anatomic coverage", "Lower dose efficiency from proportionally more over-beaming", "Eliminate over-beaming by narrowing the beam penumbra itself" ], "answer_index": 2, "explanation": "The penumbra width is roughly fixed, so with narrow collimation a larger proportion of the exposed beam falls outside the active detectors and does not contribute to the image.", "subcategory": "Radiation Safety and Dose" }, { "q": "During a retrospectively ECG-gated coronary CTA, ECG-based tube current modulation (ECG pulsing) reduces dose by:", "options": [ "Turning the tube off for the entire scan except one beat", "Lowering the mA during cardiac phases not needed for diagnosis", "Raising the pitch above 3 for every patient", "Increasing kVp during systole" ], "answer_index": 1, "explanation": "ECG pulsing keeps full tube current in the targeted phase (often diastole) and reduces it during the rest of the R-R interval, while still recording data in every phase.", "subcategory": "Radiation Safety and Dose" }, { "q": "Upgrading to a detector with higher x-ray absorption efficiency allows the facility to:", "options": [ "Scan with a smaller SFOV only", "Maintain image noise at a lower patient dose", "Eliminate the need for daily QC", "Increase spatial resolution without changing pixel size" ], "answer_index": 1, "explanation": "A more efficient detector converts more of the incident photons into signal, so the same image quality can be reached with less radiation.", "subcategory": "Radiation Safety and Dose" }, { "q": "A technologist realizes an abdomen CT was performed on the wrong patient. The most appropriate action is to:", "options": [ "Scan the correct patient and not mention the error to anyone", "Delete the images so the radiologist does not read them", "Notify the supervisor/radiologist and report it per facility policy", "Record the error only in a personal logbook for future reference" ], "answer_index": 2, "explanation": "Scanning errors must be reported and documented according to facility policy (and state rules where applicable) so the dose is recorded and the cause can be corrected.", "subcategory": "Radiation Safety and Dose" }, { "q": "Which practice best protects other staff from unnecessary exposure during CT scanning?", "options": [ "Relying on the bowtie filter to block scatter throughout the room", "Leaving the room door open so staff can observe the patient", "Having staff stand at the gantry opening to steady the patient", "Controlled room access, with anyone remaining in a lead apron" ], "answer_index": 3, "explanation": "Controlled access keeps people out of the room during exposure; anyone who must stay should wear a lead apron and stand as far from the gantry as practical.", "subcategory": "Radiation Safety and Dose" }, { "q": "Iterative reconstruction supports CT dose reduction mainly because it:", "options": [ "Lowers image noise, so fewer mAs give acceptable images", "Narrows the beam so less tissue is directly irradiated", "Filters low-energy photons before they reach the patient", "Shortens the scan range by removing extra overscan" ], "answer_index": 0, "explanation": "By modeling noise and the system, iterative methods reduce noise, allowing lower tube output for similar image quality.", "subcategory": "Radiation Safety and Dose" }, { "q": "A technologist wears a single personal dosimeter and a lead apron during a CT-guided procedure. The dosimeter should be worn:", "options": [ "At waist level, underneath the lead apron", "On the wrist of the hand nearest the gantry", "Inside the apron at the level of the chest", "At collar level, outside the lead apron" ], "answer_index": 3, "explanation": "A single badge worn at the collar outside the apron estimates dose to the unshielded head, neck and lens of the eye.", "subcategory": "Radiation Safety and Dose" }, { "q": "What is the annual whole-body occupational effective dose limit set by the NRC for radiation workers such as CT technologists?", "options": [ "50 mSv (5 rem)", "1 mSv (0.1 rem)", "5 mSv (0.5 rem)", "150 mSv (15 rem)" ], "answer_index": 0, "explanation": "The NRC whole-body occupational limit is 50 mSv per year; 1 mSv applies to the public and 150 mSv is a lens limit.", "subcategory": "Radiation Safety and Dose" }, { "q": "A facility's median CTDIvol for routine adult head CT is above the national diagnostic reference level (DRL). The facility should:", "options": [ "Stop performing head CT until a physicist certifies the unit", "Report each exam above the DRL to the state as an overdose", "Make no change, because DRLs apply only to pediatric patients", "Review and optimize the protocol, since a DRL is not a dose limit" ], "answer_index": 3, "explanation": "DRLs are investigation levels for typical patients; exceeding one prompts a protocol review, not a regulatory violation.", "subcategory": "Radiation Safety and Dose" }, { "q": "On a scanner that uses a noise index to drive automatic tube current modulation, raising the noise index will:", "options": [ "Raise the tube current and the patient dose", "Lower the tube current and the patient dose", "Increase kVp while keeping the dose the same", "Lengthen rotation time to keep noise constant" ], "answer_index": 1, "explanation": "The noise index sets the target image noise; accepting more noise lets the system use less mA and deliver less dose.", "subcategory": "Radiation Safety and Dose" }, { "q": "During a CT acquisition, scatter radiation in the scan room is highest:", "options": [ "Beside the gantry housing, perpendicular to the table", "At the control console behind the leaded window", "Near the gantry apertures, along the line of the table", "Directly above the gantry near the room ceiling" ], "answer_index": 2, "explanation": "The gantry housing shields much of the scatter, so isodose curves extend farthest out of the gantry openings along the z-axis.", "subcategory": "Radiation Safety and Dose" }, { "q": "Temporary hair loss in patients who had repeated or improperly set CT brain perfusion scans is an example of:", "options": [ "A stochastic effect with no threshold", "A hereditary (genetic) radiation effect", "A deterministic (tissue reaction) effect", "A late carcinogenic radiation effect" ], "answer_index": 2, "explanation": "Epilation occurs only above a dose threshold and worsens with dose, the hallmarks of a deterministic effect.", "subcategory": "Radiation Safety and Dose" }, { "q": "Under Joint Commission standards, which dose information must be recorded for each diagnostic CT exam?", "options": [ "An effective dose in mSv computed by the technologist", "The patient's estimated lifetime cumulative dose", "The CTDIvol, DLP or size-specific dose estimate", "The entrance skin exposure measured in roentgens" ], "answer_index": 2, "explanation": "The Joint Commission requires the CT dose index (CTDIvol, DLP or SSDE) to be recorded in a retrievable format for each study.", "subcategory": "Radiation Safety and Dose" }, { "q": "A patient's arms stay at the sides during a chest-abdomen CT using automatic tube current modulation. The system will most likely:", "options": [ "Lower the tube current at levels that include the arms", "Ignore the arms because modulation uses body weight", "Raise the tube current at levels that include the arms", "Stop the scan because the arms are outside the SFOV" ], "answer_index": 2, "explanation": "Modulation responds to the attenuation seen on the localizer, so the extra tissue of the arms drives the mA and dose up.", "subcategory": "Radiation Safety and Dose" }, { "q": "Which change lowers the DLP of an exam without changing its CTDIvol?", "options": [ "Lowering the tube current for the whole acquisition", "Limiting the scan range to the anatomy of interest", "Raising the pitch from 0.9 to 1.2 for the acquisition", "Reducing kVp from 120 to 100 with the same mAs" ], "answer_index": 1, "explanation": "DLP is CTDIvol multiplied by scan length, so shortening the range lowers DLP while the per-slice CTDIvol stays the same.", "subcategory": "Radiation Safety and Dose" }, { "q": "Under NRC regulations, the dose limit to the embryo/fetus of a declared pregnant technologist is:", "options": [ "50 mSv for the entire gestation", "5 mSv for the entire gestation", "1 mSv for each month of gestation", "20 mSv for each trimester of gestation" ], "answer_index": 1, "explanation": "The NRC limits embryo/fetal dose to 5 mSv (0.5 rem) over the full pregnancy; NCRP also advises 0.5 mSv per month once declared.", "subcategory": "Radiation Safety and Dose" }, { "q": "Which statement best describes a stochastic radiation effect?", "options": [ "Severity rises with dose above a set threshold", "The effect appears within hours of the exposure", "No effect is possible below about 0.5 Gy", "The probability, not the severity, rises with dose" ], "answer_index": 3, "explanation": "Stochastic effects such as cancer have no assumed threshold; dose changes their likelihood, not how severe they are.", "subcategory": "Radiation Safety and Dose" }, { "q": "The CTDIvol displayed for a standard adult head protocol is referenced to which phantom?", "options": [ "The 32 cm diameter acrylic (PMMA) phantom", "A 20 cm diameter water-filled QC phantom", "An anthropomorphic whole-body phantom", "The 16 cm diameter acrylic (PMMA) phantom" ], "answer_index": 3, "explanation": "Head and many pediatric protocols report CTDIvol in the 16 cm phantom, while adult body protocols use the 32 cm phantom.", "subcategory": "Radiation Safety and Dose" }, { "q": "With mA, kVp, rotation time and beam collimation fixed, increasing pitch from 1.0 to 1.5 will:", "options": [ "Decrease the CTDIvol by about one-third", "Increase the CTDIvol by about one-half", "Leave the CTDIvol completely unchanged", "Decrease the CTDIvol by about two-thirds" ], "answer_index": 0, "explanation": "CTDIvol equals CTDIw divided by pitch, so going from 1.0 to 1.5 reduces it to about 67% of its original value.", "subcategory": "Radiation Safety and Dose" } ] }, { "id": "image-production", "name": "Image Production", "main_points": [ "CT number is HU = 1000 × (μtissue − μwater) / μwater: water is 0, air −1000, fat about −50 to −100, soft tissue roughly +20 to +60, acute blood about +50 to +80, and dense bone several hundred to over +1000.", "Window width sets the range of HU shown in gray (narrow width means higher displayed contrast) and window level sets its center; the visible range is level ± width/2.", "Pixel size equals display field of view divided by matrix (e.g., 250 mm / 512 ≈ 0.49 mm); smaller pixels improve spatial resolution, but each contains fewer photons, so noise rises.", "A voxel is the pixel area times slice thickness; thicker slices lower noise but increase partial-volume averaging, while isotropic voxels give the best multiplanar and 3D reformations.", "The gantry houses the x-ray tube, generator, detectors, data acquisition system (DAS) and slip rings; slip rings allow continuous rotation for helical scanning, and the DAS digitizes detector signals.", "In MDCT, total beam collimation equals the number of active detector channels times detector width (e.g., 64 × 0.625 mm = 40 mm), which determines z-axis coverage per rotation.", "Raw (projection) data can be retrospectively reconstructed with a new kernel, slice thickness, interval or display FOV within the scan FOV; kVp, mAs, pitch, collimation and SFOV are fixed once the scan is acquired.", "Sharp (bone/high-frequency) kernels improve edge detail and spatial resolution at the cost of more noise; smooth (soft-tissue) kernels lower noise and favor contrast resolution.", "Overlapping reconstruction intervals (e.g., 1 mm slices every 0.5 mm) improve MPR and 3D quality without extra dose; MIP shows the highest-attenuation voxels (CTA), MinIP the lowest (airways), and volume rendering uses the entire dataset.", "Recognize artifacts: beam hardening (cupping, dark streaks between dense structures), partial volume, motion, metal streaks, ring (faulty detector element), out-of-field truncation, tube arcing and cone-beam artifacts on wide detectors.", "Daily QC with a water phantom checks CT number accuracy (water near 0 HU), noise (ROI standard deviation) and uniformity (center versus periphery); tube warm-up and air calibrations also protect the tube and prevent artifacts.", "Informatics: DICOM standardizes image format and transfer, PACS stores and distributes images, RIS/HIS/EHR manage orders and records, and all handling must preserve patient confidentiality, including teleradiology and downtime procedures." ], "vocabulary": [ { "term": "Hounsfield unit (HU)", "definition": "The CT number scale that expresses a voxel's attenuation relative to water (0 HU) and air (−1000 HU)." }, { "term": "Window width (WW)", "definition": "The range of CT numbers displayed as shades of gray; it controls image contrast." }, { "term": "Window level (WL)", "definition": "The CT number at the center of the displayed gray scale; it controls image brightness." }, { "term": "Pixel", "definition": "A single two-dimensional picture element in the image matrix." }, { "term": "Voxel", "definition": "A volume element: the pixel area multiplied by slice thickness." }, { "term": "Matrix", "definition": "The grid of rows and columns of pixels forming the image, typically 512 × 512 in CT." }, { "term": "Scan field of view (SFOV)", "definition": "The area within the gantry from which projection data are collected; it is set before scanning." }, { "term": "Display field of view (DFOV)", "definition": "The portion of the scanned data reconstructed into the image, which may be equal to or smaller than the SFOV." }, { "term": "Data acquisition system (DAS)", "definition": "Electronics that measure detector signals and convert them from analog to digital for the computer." }, { "term": "Slip ring", "definition": "An electromechanical device that transfers power and data across the rotating gantry, enabling continuous rotation." }, { "term": "Filtered backprojection (FBP)", "definition": "An analytic reconstruction method that applies a convolution filter to projection data and then backprojects it." }, { "term": "Iterative reconstruction", "definition": "A reconstruction method that repeatedly compares and corrects estimated images against measured data to reduce noise and artifacts." }, { "term": "Reconstruction kernel (algorithm)", "definition": "The mathematical filter used in reconstruction that trades off spatial resolution against noise." }, { "term": "Reconstruction interval", "definition": "The distance between the centers of consecutive reconstructed images, which may overlap." }, { "term": "Partial volume averaging", "definition": "Display of an averaged HU when tissues of different attenuation share one voxel." }, { "term": "Beam hardening", "definition": "Loss of lower-energy photons as the beam passes through tissue, raising the mean energy and causing cupping or streak artifacts." }, { "term": "Spatial resolution", "definition": "The ability to distinguish small, closely spaced objects, often stated in line pairs per centimeter." }, { "term": "Contrast resolution", "definition": "The ability to distinguish structures with small differences in attenuation." }, { "term": "Temporal resolution", "definition": "How quickly the data for one image is acquired, which determines how well motion is frozen." }, { "term": "DICOM", "definition": "Digital Imaging and Communications in Medicine: the standard for medical image format, storage and transfer." } ], "quiz": [ { "q": "What is the CT number of pure water, by definition?", "options": [ "0 HU", "−1000 HU", "+100 HU", "+1000 HU" ], "answer_index": 0, "explanation": "The Hounsfield scale is defined so water equals 0 HU and air approximately −1000 HU." }, { "q": "With a window width of 400 and a window level of 40, which range of CT numbers is displayed in shades of gray?", "options": [ "−400 to +400 HU", "40 to 440 HU", "−160 to +240 HU", "−200 to +200 HU" ], "answer_index": 2, "explanation": "The visible range is level ± width/2: 40 − 200 = −160 and 40 + 200 = +240." }, { "q": "A 250 mm display field of view is reconstructed with a 512 × 512 matrix. The pixel size is approximately:", "options": [ "0.25 mm", "0.49 mm", "2.0 mm", "5.1 mm" ], "answer_index": 1, "explanation": "Pixel size = DFOV ÷ matrix = 250 mm ÷ 512 ≈ 0.49 mm." }, { "q": "Which parameter can be changed retrospectively from the raw data without rescanning the patient?", "options": [ "kVp", "mAs", "Beam collimation", "Reconstruction kernel" ], "answer_index": 3, "explanation": "Kernel, slice thickness, interval and DFOV are reconstruction choices; kVp, mAs and collimation are fixed at acquisition." }, { "q": "A 64-row scanner acquires with 64 channels of 0.625 mm each. What is the total beam collimation?", "options": [ "6.4 mm", "20 mm", "64 mm", "40 mm" ], "answer_index": 3, "explanation": "Total collimation = 64 × 0.625 mm = 40 mm." }, { "q": "Switching from a soft-tissue kernel to a high-resolution bone kernel will:", "options": [ "Reduce noise and improve spatial resolution", "Improve spatial resolution and increase image noise", "Lower the radiation dose", "Improve low-contrast detectability" ], "answer_index": 1, "explanation": "Sharp kernels enhance edges and fine detail but also amplify noise." }, { "q": "Dark streaks between the petrous bones on a head CT (the Hounsfield bar) are an example of which artifact?", "options": [ "Ring artifact", "Motion artifact", "Beam hardening", "Aliasing from undersampling" ], "answer_index": 2, "explanation": "Dense bone preferentially absorbs low-energy photons, hardening the beam and producing dark streaks between dense structures." }, { "q": "A ring artifact on a third-generation scanner is most often caused by:", "options": [ "A miscalibrated or failed detector element", "Patient motion", "Metal implants", "Too high a pitch" ], "answer_index": 0, "explanation": "Because each detector traces a circle as the gantry rotates, one faulty element creates a ring." }, { "q": "Which change most directly improves temporal resolution?", "options": [ "A sharper reconstruction kernel", "Faster gantry rotation time", "A larger matrix", "Thinner reconstructed slices" ], "answer_index": 1, "explanation": "Shorter rotation time collects each image's data faster, reducing motion blur." }, { "q": "Which 3D postprocessing technique displays the highest-attenuation voxel along each ray and is commonly used for CT angiography?", "options": [ "Minimum intensity projection (MinIP)", "Shaded surface display (SSD)", "Curved planar reformation of the airway", "Maximum intensity projection (MIP)" ], "answer_index": 3, "explanation": "MIP projects the brightest voxels, highlighting contrast-filled vessels; MinIP highlights air-filled structures." }, { "q": "During daily QC, the standard deviation of CT numbers within an ROI in a water phantom is a measure of:", "options": [ "Image noise", "CT number accuracy", "Spatial resolution", "Slice sensitivity profile" ], "answer_index": 0, "explanation": "The ROI mean checks accuracy (near 0 HU for water), while the standard deviation quantifies noise." }, { "q": "Which standard governs the format and network transfer of CT images between the scanner and PACS?", "options": [ "HL7", "HIPAA", "DICOM", "JPEG" ], "answer_index": 2, "explanation": "DICOM defines medical image file structure and communication; HL7 handles text-based clinical messages, and HIPAA is a privacy law." } ], "bank": [ { "q": "The anode of a CT x-ray tube rotates during exposure mainly to:", "options": [ "Reduce the scatter reaching the detectors", "Spread heat over a larger area of the target", "Focus the electron stream onto the filament", "Increase the kVp delivered to the beam" ], "answer_index": 1, "explanation": "A rotating anode distributes the focal track's heat over a large circumference, which permits the high mA and long exposures used in CT.", "subcategory": "Image Formation" }, { "q": "Modern CT scanners use which type of generator?", "options": [ "Capacitor-discharge generator used only for portables", "High-frequency generator producing nearly constant voltage", "Three-phase, six-pulse generator with high voltage ripple", "Single-phase, self-rectified generator with full ripple" ], "answer_index": 1, "explanation": "High-frequency generators are compact (often mounted on the rotating gantry) and deliver nearly constant potential with minimal ripple.", "subcategory": "Image Formation" }, { "q": "How does a photon-counting CT detector differ from a conventional energy-integrating detector?", "options": [ "It converts x-rays to light with a scintillator first", "It measures ionization in pressurized xenon gas chambers", "It sums the total energy of all photons in each reading", "It directly converts and counts individual photons by energy" ], "answer_index": 3, "explanation": "Photon-counting detectors (for example, cadmium telluride) directly convert each photon and assign it to energy bins, improving spatial resolution and enabling spectral imaging.", "subcategory": "Image Formation" }, { "q": "Which CT component performs the high-speed mathematical calculations needed to reconstruct images?", "options": [ "Slip ring", "High-voltage generator", "Array processor", "Data acquisition system" ], "answer_index": 2, "explanation": "The array processor (reconstruction engine) handles the heavy reconstruction math so the host computer can manage scanning and display; the DAS digitizes the detector signals.", "subcategory": "Image Formation" }, { "q": "In CT terminology, the z-axis corresponds to:", "options": [ "The patient's long axis, the direction of table travel", "The left-to-right direction across the gantry opening", "The anterior-to-posterior direction through the patient", "The rows of pixels in the reconstructed image matrix" ], "answer_index": 0, "explanation": "The x- and y-axes define the axial image plane, while the z-axis runs along the patient and table, governing slice thickness and coverage.", "subcategory": "Image Formation" }, { "q": "Before scanning a bariatric patient, which equipment check is essential?", "options": [ "Patient weight within the table limit and fit within the gantry aperture", "That the x-ray tube has cooled completely to room temperature", "That the slip rings were serviced within the past week", "That the smallest SFOV is preselected to give maximum image detail" ], "answer_index": 0, "explanation": "Exceeding the table limit risks injury and equipment damage, and a body that does not fit within the aperture and SFOV causes truncation artifacts.", "subcategory": "Image Formation" }, { "q": "When setting up an abdomen CT on a large patient, the scan field of view should be:", "options": [ "Large enough to include the entire cross-section of the body", "As small as possible, to maximize spatial resolution", "Matched to the display FOV normally used for a head scan", "Chosen after scanning, since it can be enlarged from raw data" ], "answer_index": 0, "explanation": "SFOV is fixed at acquisition; anatomy outside it produces truncation artifacts and inaccurate CT numbers, and it cannot be recovered retrospectively.", "subcategory": "Image Formation" }, { "q": "A scan was acquired using a detector configuration of 16 × 1.25 mm. Which reconstructed slice thickness is NOT possible from this data?", "options": [ "5 mm", "2.5 mm", "0.625 mm", "1.25 mm" ], "answer_index": 2, "explanation": "Reconstructed slices can be equal to or thicker than the acquired detector width, but never thinner.", "subcategory": "Image Formation" }, { "q": "Which acquisition mode keeps the table stationary during each exposure and moves it between rotations?", "options": [ "Sequential (step-and-shoot) axial", "Dual-source helical at high pitch", "Helical at a pitch of 1.0", "Shuttle (toggling) mode" ], "answer_index": 0, "explanation": "In sequential mode, the tube rotates with the table still, then the table advances to the next position before the next exposure.", "subcategory": "Image Formation" }, { "q": "A scanner with a 16 cm wide detector images the entire heart in one rotation without moving the table. This is called:", "options": [ "Volumetric (wide-detector) acquisition", "Shuttle-mode acquisition", "Interleaved sequential acquisition", "Helical acquisition at high pitch" ], "answer_index": 0, "explanation": "Wide-detector volumetric scanning covers an organ in a single rotation, eliminating misregistration between table positions.", "subcategory": "Image Formation" }, { "q": "Repeated scanning of the same anatomic level over time without moving the table, as used for CT perfusion, is called:", "options": [ "Cine (continuous) mode", "Helical mode", "Step-and-shoot mode", "Scout (localizer) mode" ], "answer_index": 0, "explanation": "Cine mode acquires images at one location over time, allowing contrast to be tracked through tissue to build time-attenuation curves.", "subcategory": "Image Formation" }, { "q": "To extend perfusion coverage beyond the width of the detector, some scanners move the table back and forth between two positions during the injection. This is known as:", "options": [ "Shuttle mode", "Bolus tracking", "Over-ranging", "Retrospective gating" ], "answer_index": 0, "explanation": "Shuttle (toggling or jog) mode alternates table positions during dynamic scanning to increase z-axis coverage.", "subcategory": "Image Formation" }, { "q": "Which image can dual-energy CT generate from a single contrast-enhanced acquisition, potentially replacing a separate noncontrast scan?", "options": [ "Scanogram (scout) image", "Virtual noncontrast image", "Minimum intensity projection", "Shaded surface display" ], "answer_index": 1, "explanation": "Material decomposition subtracts iodine from the dataset to create virtual noncontrast images, which can avoid a true noncontrast series and its dose.", "subcategory": "Image Formation" }, { "q": "The main advantage of a dual-source CT scanner for cardiac imaging is:", "options": [ "Improved temporal resolution", "Improved low-contrast resolution at any dose", "Elimination of the need for ECG gating", "A larger scan field of view" ], "answer_index": 0, "explanation": "With two tubes about 90° apart, the data needed for an image are acquired in about a quarter rotation, roughly halving the temporal resolution time.", "subcategory": "Image Formation" }, { "q": "On a dual-energy scanner, which virtual monoenergetic setting best reduces metal and beam-hardening artifact?", "options": [ "High keV (for example, 130–140 keV)", "A keV equal to iodine's K-edge", "The lowest keV available", "Low keV (for example, 40–50 keV)" ], "answer_index": 0, "explanation": "High-keV monoenergetic images are less affected by beam hardening around metal, while low-keV images boost iodine contrast but worsen artifact.", "subcategory": "Image Formation" }, { "q": "Deep learning image reconstruction works by:", "options": [ "The tube current is automatically doubled for each rotation", "Projections with high noise are deleted before backprojection", "A sharper kernel is applied to every reconstructed image", "A trained neural network suppresses noise in the reconstructed data" ], "answer_index": 3, "explanation": "Deep learning reconstruction is trained on paired high- and low-quality data to suppress noise while preserving texture, enabling lower-dose scanning.", "subcategory": "Image Formation" }, { "q": "Images automatically created at the time of scanning using parameters set in the protocol beforehand are described as:", "options": [ "Prospective reconstructions", "Secondary reformats", "Postprocessed volume renderings", "Retrospective reconstructions" ], "answer_index": 0, "explanation": "Prospective reconstructions are defined before the scan; retrospective reconstructions are created later from the saved raw data with new parameters.", "subcategory": "Image Formation" }, { "q": "After a study's raw data have been purged from the scanner, which can still be done?", "options": [ "Perform a targeted reconstruction with a smaller DFOV", "Reconstruct with a different kernel", "Create multiplanar reformations from the existing image data", "Reconstruct thinner slices than those stored" ], "answer_index": 2, "explanation": "Kernel, slice thickness and targeted DFOV changes require raw data; MPRs and 3D renderings can be built from the stored image data.", "subcategory": "Image Formation" }, { "q": "A 400 mm scan range is reconstructed at a 2 mm interval. Approximately how many images will be produced?", "options": [ "800", "400", "100", "200" ], "answer_index": 3, "explanation": "Number of images ≈ range ÷ interval = 400 mm ÷ 2 mm = 200 (slice thickness does not change the count).", "subcategory": "Image Formation" }, { "q": "In helical CT, interpolation is required to:", "options": [ "Synthesize planar slice data from the helical path", "Calculate the patient's effective dose for the record", "Remove ring artifacts caused by faulty detector elements", "Convert analog detector signals into digital form" ], "answer_index": 0, "explanation": "Because the table moves during rotation, no single rotation lies in one plane; z-axis interpolation synthesizes planar data for each reconstructed image.", "subcategory": "Image Formation" }, { "q": "Which postprocessing display follows a tortuous structure, such as a coronary artery, to show its full length in a single image?", "options": [ "Shaded surface display", "Curved planar reformation", "Minimum intensity projection", "Standard coronal MPR" ], "answer_index": 1, "explanation": "Curved reformations trace a centerline through the structure, straightening it into one plane for length and stenosis evaluation.", "subcategory": "Image Formation" }, { "q": "Which 3D technique displays only voxels above a set threshold as a lit surface and discards the remaining data?", "options": [ "Maximum intensity projection", "Shaded surface display (SSD)", "Minimum intensity projection", "Volume rendering" ], "answer_index": 1, "explanation": "SSD uses a single threshold to build a surface; volume rendering, by contrast, assigns opacity and color to the entire dataset.", "subcategory": "Image Formation" }, { "q": "To measure the diameter of a tortuous aortic aneurysm accurately, the technologist should measure:", "options": [ "As the longest dimension seen on the axial image", "On a thick-slab sagittal MIP of the entire abdomen", "On the scout image, using the caliper tool", "Perpendicular to the centerline on a double-oblique MPR" ], "answer_index": 3, "explanation": "Axial measurements of an obliquely oriented vessel cut it elliptically and overestimate diameter; true short-axis measurement requires a centerline-perpendicular plane.", "subcategory": "Image Formation" }, { "q": "Magnifying an image on the workstation with the zoom tool:", "options": [ "Improves spatial resolution like a smaller DFOV reconstruction", "Changes the CT numbers in the image", "Enlarges the existing pixels without improving spatial resolution", "Reduces noise in the image" ], "answer_index": 2, "explanation": "Display zoom simply enlarges pixels; only a targeted reconstruction from raw data with a smaller DFOV produces smaller pixels and true detail.", "subcategory": "Image Evaluation and Archiving" }, { "q": "An ROI on a renal lesion measures 8 HU before contrast and 11 HU in the nephrographic phase. This indicates:", "options": [ "Dense calcification within the lesion wall", "Macroscopic fat within the lesion", "No significant enhancement, consistent with fluid", "Avid enhancement, suggesting a solid renal tumor" ], "answer_index": 2, "explanation": "A change of under about 10 HU is not considered enhancement, while an increase of 20 HU or more indicates enhancement; near-water attenuation suggests a cyst.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Spatial resolution in CT is commonly expressed and tested using:", "options": [ "Dose-length product (mGy·cm)", "Mean HU of a water phantom ROI", "Line pairs per centimeter (lp/cm)", "Standard deviation of a water ROI" ], "answer_index": 2, "explanation": "Spatial resolution is measured with high-contrast line-pair patterns or the modulation transfer function and reported in lp/cm.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Which change most improves the low-contrast detectability of a subtle liver lesion?", "options": [ "Widening the window width", "Increasing the mAs to reduce noise", "Switching to a sharper bone kernel", "Reconstructing thinner slices at the same mAs" ], "answer_index": 1, "explanation": "Low-contrast resolution is limited mainly by noise; more mAs, smoother kernels or thicker slices reduce noise, while sharper kernels and thinner slices increase it.", "subcategory": "Image Evaluation and Archiving" }, { "q": "On a daily water-phantom QC scan, the center ROI measures 2 HU and the peripheral ROIs measure about 11 HU. This result indicates a problem with:", "options": [ "Spatial resolution", "Uniformity", "Slice sensitivity profile", "Table indexing accuracy" ], "answer_index": 1, "explanation": "CT numbers across a uniform water phantom should be nearly the same everywhere; a center-to-edge difference like this suggests cupping or capping and requires recalibration or service.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A CT linearity test evaluates whether:", "options": [ "The table moves exactly the distance displayed on the console", "Image noise doubles exactly whenever the mAs is halved", "The positioning lasers align with the actual scan plane", "Measured HU values relate linearly to known attenuation coefficients" ], "answer_index": 3, "explanation": "Linearity is checked with phantom inserts of known materials; their HU values should relate linearly to their linear attenuation coefficients.", "subcategory": "Image Evaluation and Archiving" }, { "q": "ACR CT accreditation, once granted, must be renewed every:", "options": [ "1 year", "10 years", "5 years", "3 years" ], "answer_index": 3, "explanation": "ACR accreditation runs on a three-year cycle, with annual medical physicist surveys and ongoing QC required in between.", "subcategory": "Image Evaluation and Archiving" }, { "q": "The main reason to perform the manufacturer's tube warm-up procedure after the scanner has been idle is to:", "options": [ "Clear old raw data from the scanner's storage", "Reset the dose notification and alert values for the day", "Calibrate the CT number of water to exactly 0 HU", "Gradually heat the anode to prevent cracking and arcing" ], "answer_index": 3, "explanation": "Applying high loads to a cold anode can crack it or cause arcing; warm-up exposures raise its temperature gradually.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A 4 mm lung nodule measures lower attenuation on 5 mm slices than on 1 mm slices. This is caused by:", "options": [ "Beam hardening", "Edge gradient artifact", "Tube arcing", "Partial volume averaging" ], "answer_index": 3, "explanation": "When a small object occupies only part of a thick voxel, its HU is averaged with surrounding lung, lowering its measured density.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Streaks arising along a sharp, irregular interface between very different attenuations, such as dense oral contrast against bowel gas, are called:", "options": [ "Out-of-field artifacts", "Ring artifacts", "Cone-beam artifacts", "Edge gradient artifacts" ], "answer_index": 3, "explanation": "Edge gradient artifacts occur at high-contrast, irregular edges where the reconstruction cannot accurately represent the abrupt change.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A large patient's arms rest at the sides outside the scan field of view during an abdomen CT. The likely result is:", "options": [ "Ring artifacts centered in the middle of the image", "Improved uniformity across the abdomen", "Cone-beam artifacts limited to the z-axis edges", "Truncation artifacts and inaccurate peripheral CT numbers" ], "answer_index": 3, "explanation": "Tissue outside the SFOV attenuates the beam but is not fully measured, producing streaking and shading at the periphery.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Random, intense streaks across one or more images caused by an electrical discharge inside the x-ray tube are known as:", "options": [ "Partial volume artifacts", "Aliasing from undersampling", "Tube arcing artifacts", "Motion artifacts" ], "answer_index": 2, "explanation": "Arcing interrupts tube output momentarily, corrupting projections; recurring arcing often signals a failing tube.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Which approach best reduces streak artifact from a hip prosthesis?", "options": [ "Switching to a sharper bone kernel as the only change", "Reconstructing with a smaller display FOV centered on the hip", "Lowering the kVp to 80 to raise contrast around the metal", "Metal artifact reduction software, plus higher kVp or high keV" ], "answer_index": 3, "explanation": "MAR software corrects the corrupted projections, and higher beam energy lessens photon starvation; low kVp and sharp kernels make metal artifact worse.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Which system pushes scheduled patient demographics directly to the CT scanner, reducing manual entry errors?", "options": [ "The PACS long-term archive", "A burned patient CD", "DICOM modality worklist", "Teleradiology reading software" ], "answer_index": 2, "explanation": "The modality worklist service queries the RIS for scheduled exams so the scanner receives the correct name, ID and accession number.", "subcategory": "Image Evaluation and Archiving" }, { "q": "The FDA term \"medical image management and processing system\" (MIMPS) refers to systems such as:", "options": [ "Power injectors that log each contrast dose", "Personal dosimeters worn by imaging staff", "Hospital billing and insurance claim systems", "PACS that store, display and process images" ], "answer_index": 3, "explanation": "FDA classifies PACS and related image management and processing software as MIMPS devices.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Overnight CT studies are read by an off-site teleradiology group. Which requirement applies to sending the images?", "options": [ "Printing films and couriering them the next morning", "Emailing JPEG screenshots to the reading radiologist", "Stripping all identifiers so studies cannot be matched", "Secure, HIPAA-compliant transmission to authorized readers" ], "answer_index": 3, "explanation": "Teleradiology must preserve image quality (DICOM) and protect confidentiality through encrypted networks and controlled access.", "subcategory": "Image Evaluation and Archiving" }, { "q": "During an unplanned PACS outage, the technologist should:", "options": [ "Email the images to each patient so a copy is kept safe", "Stop all scanning, including stat and emergency exams", "Delete older studies on the scanner to free up local storage space", "Follow downtime procedures and send images once PACS is restored" ], "answer_index": 3, "explanation": "Downtime procedures keep patient care going safely, preserve the images and ensure every exam is reconciled and archived after recovery, with urgent findings communicated directly.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A patient breathes during a helical chest acquisition. The most typical appearance on the images is:", "options": [ "Blurring, streaks and doubled or duplicated contours", "Concentric rings centered on the isocenter of the image", "A uniform rise in CT numbers throughout the image", "Dark bands only between dense bony structures" ], "answer_index": 0, "explanation": "Motion causes inconsistent projection data, producing blur, streaks and ghosted edges such as doubled diaphragms or vessels.", "subcategory": "Image Evaluation and Archiving" }, { "q": "The CT number of a tissue is calculated as:", "options": [ "1000 × (μtissue − μwater) ÷ μwater", "1000 × (μwater − μtissue) ÷ μtissue", "100 × (μtissue − μair) ÷ μwater", "1000 × (μtissue + μwater) ÷ μair" ], "answer_index": 0, "explanation": "Hounsfield units scale each voxel's linear attenuation coefficient relative to water, so water is 0 HU and air about −1000 HU.", "subcategory": "Image Formation" }, { "q": "Lossless compression of CT images:", "options": [ "Reduces file size with no loss of image data", "Discards fine detail to reach very high ratios", "Converts images into a non-DICOM file format", "Is permitted only for images sent off-site" ], "answer_index": 0, "explanation": "Lossless (reversible) compression restores the original pixel values exactly, typically at modest ratios such as 2–3:1.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A CT angiogram has suboptimal arterial opacification. Which virtual monoenergetic setting best increases iodine contrast?", "options": [ "40–50 keV", "70–80 keV", "100–110 keV", "130–140 keV" ], "answer_index": 0, "explanation": "Low keV levels sit near iodine's K-edge (33 keV), sharply raising iodine attenuation at the cost of more noise.", "subcategory": "Image Formation" }, { "q": "A correctly performed CT study has been archived to PACS under another patient's name. The best action is to:", "options": [ "Delete the study from the scanner and send it again", "Notify the PACS administrator to correct it per policy", "Rescan the correct patient so the record is complete", "Edit the name on the reading workstation directly" ], "answer_index": 1, "explanation": "Misidentified studies are corrected (reconciled or merged) by authorized PACS staff under policy, preserving an audit trail; rescanning adds dose.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Reducing the DFOV from 400 mm to 200 mm while keeping a 512 × 512 matrix will:", "options": [ "Double the pixel size, reducing displayed spatial detail", "Halve the pixel size, improving displayed spatial detail", "Keep the pixel size but double the anatomy displayed", "Halve the patient dose while keeping the pixel size" ], "answer_index": 1, "explanation": "Pixel size equals DFOV ÷ matrix, so halving the DFOV halves pixel size (0.78 mm to 0.39 mm).", "subcategory": "Image Formation" }, { "q": "As a polyenergetic x-ray beam passes through the patient, its mean energy:", "options": [ "Increases, as lower-energy photons are preferentially absorbed", "Decreases, as higher-energy photons are preferentially absorbed", "Stays constant, because all photons are attenuated equally", "Decreases, because scatter adds low-energy photons only" ], "answer_index": 0, "explanation": "Preferential removal of low-energy photons \"hardens\" the beam, the physical basis of beam-hardening artifacts.", "subcategory": "Image Formation" }, { "q": "Raising the window level from 40 to 100 HU while keeping the same width makes soft tissue appear:", "options": [ "Brighter", "Noisier", "Sharper", "Darker" ], "answer_index": 3, "explanation": "Raising the level moves the gray scale up, so tissues with a given CT number fall lower on the scale and display darker.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A 480 mm scan range uses a 40 mm beam collimation, a pitch of 1.0 and a 0.5 s rotation. The helical scan time is approximately:", "options": [ "6 seconds", "12 seconds", "3 seconds", "9.6 seconds" ], "answer_index": 0, "explanation": "Table speed is 40 mm per 0.5 s, or 80 mm/s; 480 mm ÷ 80 mm/s = 6 s.", "subcategory": "Image Formation" }, { "q": "A modulation transfer function (MTF) curve is used to describe:", "options": [ "How image noise changes as the tube current increases", "How CT numbers change across the width of a water phantom", "How well contrast is preserved as spatial frequency increases", "How patient dose changes as the scan length increases" ], "answer_index": 2, "explanation": "MTF characterizes spatial resolution: the higher the MTF at a given frequency, the better fine detail is reproduced.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Wide-detector scanners use which reconstruction approach to account for beam divergence along the z-axis?", "options": [ "Simple unfiltered back projection only", "Cone-beam (e.g., Feldkamp-type) reconstruction", "Two-dimensional fan-beam reconstruction", "Single-row 360° linear interpolation" ], "answer_index": 1, "explanation": "With many rows the x-ray beam is a cone, not a flat fan, so reconstruction must model the divergent ray paths.", "subcategory": "Image Formation" }, { "q": "A protocol uses 200 mAs per rotation at a pitch of 0.8. The effective mAs (mAs ÷ pitch) is:", "options": [ "250 mAs", "160 mAs", "200 mAs", "320 mAs" ], "answer_index": 0, "explanation": "Effective mAs = mAs per rotation ÷ pitch: 200 ÷ 0.8 = 250.", "subcategory": "Image Formation" }, { "q": "Compared with 360° linear interpolation, 180° linear interpolation in single-row helical CT produces:", "options": [ "A thinner effective slice but more image noise", "A thicker effective slice and less image noise", "A thinner effective slice and less image noise", "The same slice profile with a higher patient dose" ], "answer_index": 0, "explanation": "Using data closer to each slice position narrows the slice sensitivity profile, but fewer data points mean more noise.", "subcategory": "Image Formation" }, { "q": "Stair-step artifacts on coronal and 3D reformations are best reduced by:", "options": [ "Thicker slices reconstructed with no slice overlap", "Thin slices reconstructed with overlapping intervals", "A sharper bone kernel applied to the axial images", "A wider window width set on the reformatted images" ], "answer_index": 1, "explanation": "Stair-step artifacts come from coarse z-axis sampling; thinner, overlapping reconstructions smooth the steps.", "subcategory": "Image Evaluation and Archiving" }, { "q": "DICOM Modality Performed Procedure Step (MPPS) allows the scanner to:", "options": [ "Report to the RIS that an exam has started or been completed", "Retrieve the patient's prior images from the archive", "Compress images before they are sent to the PACS", "Calibrate reading monitors to a common gray scale" ], "answer_index": 0, "explanation": "MPPS messages tell the RIS and PACS what was actually performed, updating exam status and supporting billing.", "subcategory": "Image Evaluation and Archiving" }, { "q": "The full width at half maximum (FWHM) of a slice sensitivity profile describes the:", "options": [ "In-plane spatial resolution in lp/cm", "Effective (reconstructed) slice thickness", "Noise level in a uniform water phantom", "CT number accuracy for a known material" ], "answer_index": 1, "explanation": "The slice sensitivity profile shows how the slice responds along z; its FWHM is the effective slice thickness.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Narrowing the window width on a displayed image will:", "options": [ "Decrease displayed contrast across a larger range of HU values", "Make the whole image brighter without changing contrast", "Increase displayed contrast across a smaller range of HU values", "Reduce image noise by averaging neighboring pixels" ], "answer_index": 2, "explanation": "A narrower width assigns all gray shades to fewer HU values, so small attenuation differences look more different.", "subcategory": "Image Evaluation and Archiving" }, { "q": "CT images are commonly stored with 12 bits per pixel. How many distinct gray values can each pixel hold?", "options": [ "256", "1,024", "65,536", "4,096" ], "answer_index": 3, "explanation": "2^12 = 4,096 values, roughly covering −1024 to +3071 HU.", "subcategory": "Image Formation" }, { "q": "Patient demographics and acquisition parameters such as kVp and slice thickness are stored with each CT image in the:", "options": [ "HL7 order message", "Raw projection file", "PACS audit log", "DICOM header (metadata)" ], "answer_index": 3, "explanation": "Each DICOM object carries a header of tagged data elements describing the patient, study and technique.", "subcategory": "Image Evaluation and Archiving" }, { "q": "What is the main job of the data acquisition system (DAS)?", "options": [ "Stores finished images until they are sent to the archive", "Shapes the beam and removes low-energy photons from it", "Amplifies detector signals and converts them to digital data", "Supplies high voltage to the x-ray tube during rotation" ], "answer_index": 2, "explanation": "The DAS sits between the detectors and the computer, measuring, amplifying and digitizing the transmitted signal.", "subcategory": "Image Formation" }, { "q": "Raw projection data displayed by detector position on one axis and view angle on the other is called a:", "options": [ "Scanogram", "Sinogram", "Histogram", "Topogram" ], "answer_index": 1, "explanation": "A sinogram plots projection data against view angle; a point object traces a sine curve, hence the name.", "subcategory": "Image Formation" }, { "q": "In the ACR CT accreditation phantom, which module is used to assess low-contrast resolution?", "options": [ "Module 1", "Module 3", "Module 2", "Module 4" ], "answer_index": 2, "explanation": "Module 1 tests positioning, CT number accuracy and slice width; module 2 low contrast; module 3 uniformity and noise; module 4 high-contrast resolution.", "subcategory": "Image Evaluation and Archiving" }, { "q": "An iodine map (iodine density image) from dual-energy CT is useful mainly because it:", "options": [ "Removes all calcium so coronary stents can be measured", "Shows where iodine is distributed, helping confirm enhancement", "Replaces the need for any IV contrast in later exams", "Displays bone only, for 3D surgical planning images" ], "answer_index": 1, "explanation": "Material decomposition isolates iodine, so lesion enhancement and perfusion defects can be assessed from one contrast scan.", "subcategory": "Image Formation" }, { "q": "Selecting the small focal spot for a high-resolution temporal bone scan mainly:", "options": [ "Improves contrast resolution and allows higher tube loading", "Reduces patient dose and allows a faster rotation time", "Reduces image noise but increases geometric blur", "Improves spatial resolution but limits allowable tube loading" ], "answer_index": 3, "explanation": "A smaller focal spot reduces geometric unsharpness, but concentrates heat, so the maximum mA is lower.", "subcategory": "Image Formation" }, { "q": "Which daily water-phantom mean CT number would fall outside the ACR acceptance limits for water?", "options": [ "+2 HU", "−3 HU", "+4 HU", "+12 HU" ], "answer_index": 3, "explanation": "The ACR acceptance range for water is 0 ± 7 HU, so a mean of +12 HU fails and needs recalibration or service.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Before CT images are used in a teaching file outside the facility, the technologist should:", "options": [ "Change only the patient's name and keep the other header data", "Convert the images to JPEG, which removes all header data", "Remove identifiers from the DICOM header and any burned-in text", "Obtain the referring physician's signature on each image" ], "answer_index": 2, "explanation": "HIPAA requires de-identification, including header fields and annotations burned into pixels, before images are shared outside care.", "subcategory": "Image Evaluation and Archiving" }, { "q": "On a properly calibrated scanner, an ROI placed in air should measure approximately:", "options": [ "−100 HU", "−1000 HU", "0 HU", "+1000 HU" ], "answer_index": 1, "explanation": "Air has almost no attenuation relative to water, so by definition it measures about −1000 HU.", "subcategory": "Image Formation" }, { "q": "The contrast-to-noise ratio of a subtle liver lesion will improve when:", "options": [ "The window width is narrowed on the reading workstation", "The DFOV is reduced without changing the acquisition", "A sharper kernel is applied to the original raw data", "The lesion-to-liver HU difference increases or noise decreases" ], "answer_index": 3, "explanation": "CNR is the attenuation difference divided by noise; display settings do not change it, but better enhancement or less noise do.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Which standard is used to exchange text data, such as orders and results, between the HIS and the RIS?", "options": [ "DICOM Part 14 (GSDF)", "JPEG 2000 compression", "Health Level Seven (HL7)", "Integrated DICOM SR" ], "answer_index": 2, "explanation": "HL7 is the messaging standard for clinical text and administrative data; DICOM handles images.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Which dual-energy technique alternates the tube voltage between low and high kVp during a single rotation?", "options": [ "Dual-source imaging with two tubes", "Dual-layer detector energy separation", "Rapid kVp switching with a single tube", "Split-filter beam with a tin/gold filter" ], "answer_index": 2, "explanation": "Fast kV switching changes tube voltage view-to-view, giving near-simultaneous low- and high-energy projections from one source.", "subcategory": "Image Formation" }, { "q": "Reconstructing 1 mm images at a 0.5 mm interval (50% overlap) mainly improves:", "options": [ "The temporal resolution of each axial image", "The quality of multiplanar and 3D reformations", "The patient dose efficiency of the acquisition", "The low-contrast detectability of each image" ], "answer_index": 1, "explanation": "Overlapping reconstruction increases z-axis sampling, giving smoother reformations and fewer stair-step artifacts without extra dose.", "subcategory": "Image Formation" }, { "q": "Which QC test confirms that the external positioning lights coincide with the actual scan plane?", "options": [ "Laser light (localization) accuracy test", "CT number linearity test with inserts", "High-contrast spatial resolution test", "Water-phantom noise and uniformity test" ], "answer_index": 0, "explanation": "The localization light test scans a marker aligned with the lasers to verify they match the irradiated plane.", "subcategory": "Image Evaluation and Archiving" }, { "q": "A dual-layer (sandwich) detector obtains spectral data by:", "options": [ "Switching tube voltage from 80 to 140 kVp during each rotation", "Using two x-ray tubes mounted about 90 degrees apart", "Scanning the same anatomy twice at two different kVp settings", "Absorbing lower energies in the top layer and higher in the bottom" ], "answer_index": 3, "explanation": "The upper layer preferentially absorbs low-energy photons and the lower layer the higher-energy remainder, so every scan contains spectral data.", "subcategory": "Image Formation" }, { "q": "In filtered back projection, the convolution (filter) step is applied to:", "options": [ "Remove the star-like blurring of simple back projection", "Correct patient motion that occurred during the rotation", "Convert the digital image back into analog projections", "Remove the noise that dose reduction leaves in the image" ], "answer_index": 0, "explanation": "Simple back projection blurs every point; convolving the projections with a kernel before back projection corrects this.", "subcategory": "Image Formation" }, { "q": "The bowtie filter in a CT scanner mainly:", "options": [ "Removes scatter radiation before it reaches the detectors", "Converts the polyenergetic beam into a monoenergetic one", "Reduces beam intensity at the thinner periphery of the body", "Increases beam intensity at the edges of the scan field" ], "answer_index": 2, "explanation": "Shaping the beam to the body's cross-section lowers peripheral dose and evens out the intensity reaching the detectors.", "subcategory": "Image Formation" }, { "q": "Slip-ring technology was essential to the development of helical CT because it:", "options": [ "Removes the need for a detector array behind the patient", "Keeps the table still while the tube rotates continuously", "Lets the x-ray tube cool between each axial rotation", "Allows continuous gantry rotation without cables winding" ], "answer_index": 3, "explanation": "Slip rings transfer power and data through sliding contacts, so the gantry can rotate continuously while the table moves.", "subcategory": "Image Formation" }, { "q": "Which information system manages radiology orders, scheduling and the radiologist's reports?", "options": [ "Picture archiving and communication system", "Radiology information system (RIS)", "DICOM modality performed procedure step", "Hospital-wide laboratory information system" ], "answer_index": 1, "explanation": "The RIS handles departmental workflow such as orders, scheduling, tracking and reports; PACS stores and displays images.", "subcategory": "Image Evaluation and Archiving" }, { "q": "The linear attenuation coefficient of a tissue depends on the:", "options": [ "Matrix size, display field of view and window width", "Reconstruction kernel, slice interval and pitch used", "Rotation time, table speed and gantry tilt angle", "Photon energy, tissue density and effective atomic number" ], "answer_index": 3, "explanation": "Attenuation depends on the beam energy and the physical properties of the tissue, which is why CT numbers vary with kVp.", "subcategory": "Image Formation" }, { "q": "Diagnostic workstation monitors are calibrated so that gray levels appear consistent across displays using the:", "options": [ "HL7 Clinical Document Architecture", "NEMA XR-25 dose check standard", "ACR CT accreditation phantom", "DICOM Grayscale Standard Display Function" ], "answer_index": 3, "explanation": "DICOM Part 14 GSDF maps pixel values to perceptually linear luminance so an image looks the same on calibrated monitors.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Antiscatter septa placed in front of the CT detector array mainly serve to:", "options": [ "Shape the beam to match the patient's cross-section", "Set the total beam width along the patient's z-axis", "Convert x-ray photons into visible light for readout", "Absorb scattered photons before they reach the detectors" ], "answer_index": 3, "explanation": "Post-patient collimation (antiscatter septa or grids) rejects scatter arriving at oblique angles, improving contrast.", "subcategory": "Image Formation" }, { "q": "Alternating bright and dark streaks radiating from high-contrast edges, which appear to rotate as you scroll through helical images, are called:", "options": [ "Ring artifacts", "Cupping artifacts", "Windmill artifacts", "Tube arcing artifacts" ], "answer_index": 2, "explanation": "Windmill artifacts result from helical interpolation across detector rows near sharp z-axis transitions; z flying focal spot reduces them.", "subcategory": "Image Evaluation and Archiving" }, { "q": "In an energy-integrating CT detector, the scintillator converts x-ray photons into:", "options": [ "Electrons, which are counted individually by energy bin", "Light, which photodiodes convert to an electrical signal", "Ion pairs in pressurized xenon gas between charged plates", "Heat, which is measured as a change in electrical resistance" ], "answer_index": 1, "explanation": "Solid-state scintillators such as ceramic gadolinium oxysulfide emit light that photodiodes turn into a signal proportional to energy deposited.", "subcategory": "Image Formation" }, { "q": "How many pixels does a 512 × 512 image matrix contain?", "options": [ "1,024", "131,072", "262,144", "524,288" ], "answer_index": 2, "explanation": "512 × 512 = 262,144 pixels.", "subcategory": "Image Formation" }, { "q": "A z-axis flying focal spot technique mainly:", "options": [ "Spreads anode heat by moving the focal spot in x and y", "Switches tube voltage rapidly for dual-energy imaging", "Doubles z-axis sampling, improving through-plane detail", "Moves the table back and forth to extend coverage" ], "answer_index": 2, "explanation": "Deflecting the focal spot between two z positions doubles the number of overlapping slices sampled, sharpening z resolution and reducing windmill artifact.", "subcategory": "Image Formation" }, { "q": "On a multidetector scanner, the pre-patient (source) collimator primarily determines the:", "options": [ "Total beam width along the z-axis", "Reconstruction kernel of the images", "Display field of view of the images", "Number of views per gantry rotation" ], "answer_index": 0, "explanation": "The source collimator restricts the beam to the selected total collimation, which sets z-axis coverage per rotation and limits dose.", "subcategory": "Image Formation" }, { "q": "Horizontal streaks across the lower cervical spine at the shoulders on a trauma C-spine CT are mainly caused by:", "options": [ "A miscalibrated detector element in the central channels", "Too narrow a window width on the soft-tissue images", "Partial volume averaging of the vertebral bodies", "Photon starvation through the highly attenuating shoulders" ], "answer_index": 3, "explanation": "Too few photons reach the detectors through the dense lateral path, so noisy projections produce streaks.", "subcategory": "Image Evaluation and Archiving" }, { "q": "An image has 0.7 mm × 0.7 mm pixels and a 3 mm slice thickness. The voxel volume is approximately:", "options": [ "2.10 mm³", "0.49 mm³", "1.47 mm³", "4.41 mm³" ], "answer_index": 2, "explanation": "Voxel volume is pixel width × pixel height × slice thickness: 0.7 × 0.7 × 3 = 1.47 mm³.", "subcategory": "Image Formation" }, { "q": "Third-generation CT geometry, used by most modern scanners, is best described as:", "options": [ "Rotate-stationary: the tube rotates inside a fixed detector ring", "Translate-rotate: a pencil beam moves across, then rotates", "Rotate-rotate: the tube and an arc of detectors rotate together", "Electron beam: no moving parts, with fixed tungsten target rings" ], "answer_index": 2, "explanation": "In third-generation designs the tube and an opposing curved detector array rotate together around the patient.", "subcategory": "Image Formation" }, { "q": "An isotropic voxel is one in which:", "options": [ "The slice is thicker than the pixel width", "The matrix is larger than 512 × 512", "The pixel is smaller than the slice gap", "All three dimensions are equal in size" ], "answer_index": 3, "explanation": "Equal x, y and z dimensions let reformations in any plane have the same resolution as the axial images.", "subcategory": "Image Formation" }, { "q": "A detector configuration of 32 × 1.2 mm is used with a pitch of 1.5. How far does the table move per rotation?", "options": [ "25.6 mm", "57.6 mm", "38.4 mm", "48.0 mm" ], "answer_index": 1, "explanation": "Total collimation is 32 × 1.2 = 38.4 mm; table feed = pitch × collimation = 1.5 × 38.4 = 57.6 mm.", "subcategory": "Image Formation" }, { "q": "Halving slice thickness from 2 mm to 1 mm with all other factors constant increases image noise by about:", "options": [ "25%", "41%", "50%", "100%" ], "answer_index": 1, "explanation": "Noise varies with 1/√(photons); halving thickness halves the photons per voxel, so noise rises by √2, about 41%.", "subcategory": "Image Evaluation and Archiving" }, { "q": "Artifacts that worsen toward the outer rows of a very wide detector and come from divergent x-rays along the z-axis are called:", "options": [ "Cone-beam artifacts", "Ring artifacts", "Aliasing artifacts", "Truncation artifacts" ], "answer_index": 0, "explanation": "As the cone angle increases, rays at the outer rows pass obliquely through the voxels, causing distortion and streaks.", "subcategory": "Image Evaluation and Archiving" } ] }, { "id": "procedures", "name": "Procedures", "main_points": [ "Noncontrast head CT is the first study for acute stroke and head trauma to exclude hemorrhage, which appears hyperdense; brain perfusion repeats cine scanning through a contrast bolus to map CBF, CBV and MTT/Tmax.", "Temporal bone/IAC and sinus studies use thin slices, bone kernels and small DFOVs, with coronal reformations best showing the ostiomeatal complex; head scans are planned to avoid the lenses when possible.", "Spine CT is reconstructed in bone and soft-tissue kernels with sagittal and coronal MPRs; CT myelography follows intrathecal contrast injection, and cervical trauma scans must include the cervicothoracic junction.", "For extremity CT, position the part near isocenter and away from the torso when possible (e.g., unilateral wrist overhead), use thin slices, and add MPR/3D volume rendering for fracture and surgical planning; scan arthrograms promptly after intra-articular injection.", "Soft-tissue neck CT typically covers the skull base to the aortic arch with IV contrast; depress the shoulders to reduce streaks, and use phonation (\"eee\") or modified Valsalva maneuvers to evaluate the larynx and hypopharynx.", "CT pulmonary angiography uses bolus tracking in the main pulmonary artery; coach a gentle breath-hold and avoid a forceful Valsalva, which can draw unopacified IVC blood into the right heart and cause a transient contrast interruption.", "Coronary CTA aims for a low, steady heart rate (often below about 60–65 bpm) using beta-blockers such as metoprolol and uses sublingual nitroglycerin to dilate coronaries, which is withheld after recent PDE-5 inhibitors or with hypotension.", "Prospective ECG triggering (step-and-shoot) gives the lowest cardiac dose; retrospective gating scans continuously at low pitch for multiphase/functional data at higher dose; calcium scoring is noncontrast (Agatston method, 130 HU threshold), and TAVR planning adds gated aortic-root and iliofemoral access imaging.", "Low-dose lung cancer screening (USPSTF 2021) is for adults 50–80 years old with at least a 20 pack-year history who smoke now or quit within the past 15 years; HRCT uses thin, sharp-kernel images with prone and expiratory views as needed.", "Multiphase liver imaging uses a late arterial phase (about 35–40 s) for hypervascular lesions such as HCC, a portal venous phase (about 60–70 s) and delayed images for washout; pancreatic protocols add a pancreatic parenchymal phase (about 40–45 s).", "Renal mass protocols include noncontrast, corticomedullary, nephrographic (about 90–100 s, best for lesion detection) and excretory (about 5–10 min) phases; adrenal nodules under 10 HU on noncontrast CT are typically lipid-rich adenomas, and washout uses a 15-minute delay.", "Renal stone CT is noncontrast and low dose; CT cystography needs retrograde filling of the bladder through a Foley with diluted contrast (at least about 300–350 mL); CT colonography uses bowel prep, fecal tagging, CO2 insufflation and supine plus prone scans; enterography uses neutral oral contrast." ], "vocabulary": [ { "term": "CT perfusion", "definition": "Dynamic repeated scanning during a contrast bolus to calculate blood flow parameters in tissue such as the brain." }, { "term": "Cerebral blood volume (CBV)", "definition": "The volume of blood per unit of brain tissue, a key perfusion map." }, { "term": "Mean transit time (MTT)", "definition": "The average time contrast takes to pass through a tissue's vasculature." }, { "term": "Ostiomeatal complex", "definition": "The drainage pathway of the frontal, maxillary and anterior ethmoid sinuses, best seen on coronal CT." }, { "term": "CT myelography", "definition": "CT of the spine performed after intrathecal contrast injection to outline the spinal cord and nerve roots." }, { "term": "CT arthrography", "definition": "CT performed after intra-articular contrast injection to evaluate cartilage, labrum and ligaments." }, { "term": "Prospective ECG triggering", "definition": "Cardiac technique in which the tube is on only during a selected portion of the R-R interval, minimizing dose." }, { "term": "Retrospective ECG gating", "definition": "Continuous low-pitch helical cardiac scanning with images later sorted by cardiac phase from the recorded ECG." }, { "term": "Agatston score", "definition": "A coronary calcium score based on calcified plaque area and peak density above 130 HU on noncontrast CT." }, { "term": "TAVR planning CT", "definition": "Imaging that measures the aortic annulus and root and assesses iliofemoral access before transcatheter aortic valve replacement." }, { "term": "HRCT", "definition": "High-resolution chest CT using thin sections and a sharp kernel to evaluate interstitial lung disease." }, { "term": "Low-dose CT (LDCT) lung screening", "definition": "Annual reduced-dose noncontrast chest CT for eligible high-risk adults to detect early lung cancer." }, { "term": "Late arterial phase", "definition": "Post-injection phase (around 35–40 s) when hypervascular liver lesions enhance most conspicuously." }, { "term": "Portal venous phase", "definition": "Phase (around 60–70 s) with peak liver parenchymal and portal vein enhancement." }, { "term": "Nephrographic phase", "definition": "Phase (around 90–100 s) of homogeneous renal parenchymal enhancement, best for detecting renal masses." }, { "term": "Excretory phase", "definition": "Delayed phase (several minutes) when contrast fills the collecting systems, ureters and bladder." }, { "term": "Adrenal washout", "definition": "Calculation comparing enhanced and delayed (15-minute) attenuation to characterize an adrenal nodule." }, { "term": "CT cystography", "definition": "CT after retrograde filling of the bladder with diluted contrast through a catheter to detect bladder injury." }, { "term": "CT colonography", "definition": "Low-dose CT of a cleansed, gas-distended colon in supine and prone positions to detect polyps." }, { "term": "CT enterography", "definition": "Small-bowel CT using large-volume neutral oral contrast and IV contrast timed to the enteric phase." } ], "quiz": [ { "q": "A patient arrives with sudden left-sided weakness and suspected acute stroke. Which CT exam is performed first?", "options": [ "Contrast-enhanced head CT with 5-minute delay", "CT of the cervical spine", "Noncontrast head CT", "CT venogram only" ], "answer_index": 2, "explanation": "Noncontrast CT quickly excludes hemorrhage before thrombolysis or further vascular imaging." }, { "q": "In CT brain perfusion, which map represents the amount of blood per unit volume of brain tissue?", "options": [ "Cerebral blood volume (CBV)", "Mean transit time (MTT)", "Time to peak (TTP)", "Cerebral blood flow (CBF)" ], "answer_index": 0, "explanation": "CBV is the blood volume per unit tissue; CBF is volume per unit time and MTT is passage time." }, { "q": "For CT myelography, contrast is administered by which route?", "options": [ "Intravenous", "Intra-articular", "Oral", "Intrathecal" ], "answer_index": 3, "explanation": "Contrast is injected into the subarachnoid space, usually by lumbar puncture, before CT." }, { "q": "For a unilateral wrist CT, the patient is often placed prone with the affected arm extended overhead primarily to:", "options": [ "Make IV injection easier", "Center the wrist near isocenter away from the torso, reducing artifact and dose", "Allow a faster pitch", "Shorten the scout scan" ], "answer_index": 1, "explanation": "Keeping the wrist away from the body avoids torso streak artifact and unnecessary irradiation of the trunk." }, { "q": "Sublingual nitroglycerin before coronary CTA should be withheld in a patient who:", "options": [ "Took sildenafil within the past 24 hours", "Has a heart rate of 58 bpm", "Has an eGFR of 70", "Has a coronary calcium score of zero" ], "answer_index": 0, "explanation": "Combining nitrates with PDE-5 inhibitors can cause severe hypotension." }, { "q": "Coronary artery calcium scoring is performed:", "options": [ "With an arterial-phase contrast bolus", "With oral contrast only", "Without IV contrast, using a 130 HU threshold", "With delayed imaging at 10 minutes" ], "answer_index": 2, "explanation": "Calcium scoring is noncontrast; the Agatston method counts lesions at or above 130 HU." }, { "q": "Under the 2021 USPSTF criteria, which patient is eligible for low-dose CT lung cancer screening?", "options": [ "A 45-year-old current smoker with a 25 pack-year history", "A 62-year-old with a 30 pack-year history who quit smoking 8 years ago", "A 70-year-old with a 30 pack-year history who quit 20 years ago", "A 55-year-old never-smoker with a family history of lung cancer" ], "answer_index": 1, "explanation": "Eligibility is age 50–80, at least 20 pack-years, and currently smoking or quit within 15 years." }, { "q": "Prone images are added to an HRCT chest exam mainly to:", "options": [ "Reduce radiation dose", "Opacify the pulmonary arteries", "Evaluate air trapping", "Distinguish dependent atelectasis from early interstitial disease" ], "answer_index": 3, "explanation": "Dependent density that resolves when prone is atelectasis; persistent findings suggest true disease (expiratory images assess air trapping)." }, { "q": "Hepatocellular carcinoma is typically most conspicuous in which contrast phase?", "options": [ "Noncontrast phase", "Portal venous phase only", "Excretory phase", "Late arterial phase" ], "answer_index": 3, "explanation": "HCC is hypervascular and enhances avidly in the late arterial phase, often washing out on later phases." }, { "q": "An incidental adrenal nodule measures 6 HU on noncontrast CT. This most likely represents:", "options": [ "An adrenal hemorrhage", "A lipid-rich adrenal adenoma", "A pheochromocytoma", "A metastasis" ], "answer_index": 1, "explanation": "A noncontrast attenuation of 10 HU or less is characteristic of a lipid-rich adenoma." }, { "q": "To exclude bladder rupture after pelvic trauma, a CT cystogram should be performed by:", "options": [ "Clamping the Foley and waiting for excretory filling", "Giving oral contrast 2 hours before scanning", "Retrograde filling of the bladder with diluted contrast through a Foley catheter", "Scanning without contrast" ], "answer_index": 2, "explanation": "Active retrograde distension (around 300–350 mL or more) is needed; passive excretory filling can miss a rupture." }, { "q": "Which is standard technique for CT colonography?", "options": [ "Colonic distension with CO2 and imaging in both supine and prone positions", "IV contrast in the arterial phase with a single supine scan", "Positive oral contrast without bowel preparation", "A single prone scan with water enema" ], "answer_index": 0, "explanation": "Gas distension with supine and prone views shifts fluid and stool and improves polyp detection." } ], "bank": [ { "q": "Axial head CT is commonly planned parallel to which baseline to help keep the lenses out of the primary beam?", "options": [ "Mentomeatal line", "Acanthiomeatal line", "Supraorbitomeatal line", "Infraorbitomeatal line" ], "answer_index": 2, "explanation": "Scanning parallel to a baseline above the orbits, such as the supraorbitomeatal line, places the lenses outside the scan plane.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "On CT brain perfusion maps, the ischemic penumbra (salvageable tissue) typically shows:", "options": [ "Shortened MTT with increased CBF", "Markedly reduced CBV and reduced CBF", "Prolonged MTT/Tmax with preserved CBV", "Normal values on every perfusion map" ], "answer_index": 2, "explanation": "Penumbra is underperfused but viable, so transit times are prolonged while blood volume is maintained; the infarct core has markedly reduced CBV.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A CT venogram of the head is ordered for headache in a postpartum patient. The study is designed to show:", "options": [ "Acute hemorrhage on a noncontrast scan", "Stenosis at the carotid bifurcation", "An aneurysm at the circle of Willis", "A filling defect in a dural venous sinus" ], "answer_index": 3, "explanation": "CT venography is timed to opacify the dural sinuses and cortical veins so thrombus appears as a filling defect (for example, the empty delta sign).", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "For a head and neck CTA using bolus tracking, the monitoring ROI is commonly placed in the:", "options": [ "Internal jugular vein", "Aortic arch or ascending aorta", "Superior sagittal sinus", "Tip of the basilar artery" ], "answer_index": 1, "explanation": "Triggering from the aortic arch ensures arterial opacification from the arch to the circle of Willis before venous contamination.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A metalworker may have a metallic foreign body in the eye. Which imaging is most appropriate first?", "options": [ "Noncontrast CT of the orbits", "MRI of the orbits", "Contrast-enhanced head CT only", "CT perfusion of the brain" ], "answer_index": 0, "explanation": "CT locates metallic intraocular fragments quickly and safely; MRI could move a ferromagnetic fragment and injure the eye.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Which tiny structures require submillimeter, bone-kernel images in temporal bone CT?", "options": [ "The pituitary gland", "The middle ear ossicles", "The optic chiasm", "The basal ganglia nuclei" ], "answer_index": 1, "explanation": "The malleus, incus and stapes are only a few millimeters in size, so temporal bone CT uses very thin slices, small DFOVs and a sharp kernel.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "By definition, all Le Fort fractures of the midface involve the:", "options": [ "Frontal sinus", "Mandibular condyles", "Zygomatic arches only", "Pterygoid plates" ], "answer_index": 3, "explanation": "Le Fort I, II and III fractures all extend through the pterygoid plates of the sphenoid bone; the levels differ by the upper facial structures involved.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "For a dedicated mandible CT, which postprocessing display shows the entire mandible in a single image similar to a dental panoramic radiograph?", "options": [ "A thick-slab axial maximum intensity projection", "A straight coronal multiplanar reformat", "A minimum intensity projection", "A curved (panoramic) reformation" ], "answer_index": 3, "explanation": "A curved reformat traced along the arch unrolls the mandible, aiding evaluation of fractures, lesions and the inferior alveolar canal.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "TMJ CT is often performed in both closed- and open-mouth positions to:", "options": [ "Lower the radiation dose to the lenses", "Assess condylar translation", "Evaluate the parotid salivary ducts", "Reduce dental amalgam artifact" ], "answer_index": 1, "explanation": "Comparing positions shows how the condyle moves relative to the articular eminence, which helps evaluate joint dysfunction.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "To reduce motion during an unsedated head CT in a 2-month-old infant, the best approach is to:", "options": [ "Schedule general anesthesia for every infant", "Raise the pitch and skip immobilization", "Have a parent hold the head without a lead apron", "Feed and swaddle the infant just before scanning" ], "answer_index": 3, "explanation": "Feed-and-wrap techniques often let young infants sleep through a fast scan; immobilization aids are used, and a parent who helps must wear protection.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "On cervical spine CT, the atlantodental interval is measured between the:", "options": [ "Anterior arch of C1 and the dens", "C1 and C2 spinous processes", "Dens and the basion", "Occipital condyles and C1 lateral masses" ], "answer_index": 0, "explanation": "Widening of the atlantodental interval suggests transverse ligament injury or atlantoaxial instability.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A trauma patient has just had a chest, abdomen and pelvis CT. The best way to obtain thoracolumbar spine images is to:", "options": [ "Obtain spine radiographs instead of any CT reconstructions", "Retrospectively reconstruct the raw data with a bone kernel and small DFOV", "Rescan the spine with a separate dedicated low-pitch acquisition", "Reformat the soft-tissue axial images at the full body DFOV" ], "answer_index": 1, "explanation": "Targeted reconstructions from the existing dataset give diagnostic spine images without additional radiation.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Spondylolysis, a defect of the pars interarticularis, is best demonstrated on lumbar spine CT in which plane?", "options": [ "Sagittal reformations", "Axial images alone", "Coronal reformations", "Curved reformations" ], "answer_index": 0, "explanation": "Sagittal reformations show the pars between the superior and inferior articular processes, where a lucent defect is easiest to see.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Before a postmyelogram CT, the patient is often rolled or turned. The purpose is to:", "options": [ "Mix contrast with CSF so it does not layer", "Allow the contrast to be absorbed before scanning", "Move the contrast into the epidural venous plexus", "Lower the patient's radiation dose for the scan" ], "answer_index": 0, "explanation": "Iodinated contrast is denser than CSF and pools dependently; turning the patient distributes it evenly around the cord and nerve roots.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "On a CT shoulder arthrogram, dilute intra-articular contrast primarily helps evaluate the:", "options": [ "Axillary lymph nodes", "Bone marrow edema", "Labrum and articular cartilage", "Brachial plexus nerve roots" ], "answer_index": 2, "explanation": "Contrast distends the joint and outlines the labrum and cartilage, revealing tears that are invisible on noncontrast CT.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "On a contrast-enhanced pelvic trauma CT, a focal contrast blush that enlarges on delayed images indicates:", "options": [ "A stable, contained pseudoaneurysm", "Normal filling of the urinary bladder", "Active arterial extravasation", "Partial volume averaging artifact" ], "answer_index": 2, "explanation": "A blush that grows or changes shape on delayed images is active hemorrhage and may need urgent embolization; a pseudoaneurysm keeps the same size and follows the blood pool.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A femoral version (anteversion) CT requires axial images through:", "options": [ "The tibial plateaus only", "The sacroiliac joints and pubic symphysis", "The femoral necks and the distal femoral condyles", "The acetabula and the femoral heads only" ], "answer_index": 2, "explanation": "Femoral version is the angle between the femoral neck axis and the posterior condylar line, so both regions must be imaged without moving the patient.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Before a CT-guided biopsy, a radiopaque grid is placed on the patient's skin to:", "options": [ "Calibrate the CT numbers of tissue", "Shield the skin from radiation", "Localize the needle entry site", "Reduce streak artifact at the skin" ], "answer_index": 2, "explanation": "The grid's markers appear on the planning scan so the radiologist can mark the exact skin entry point relative to the target.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "For scaphoid fracture evaluation on wrist CT, the most useful reformations are oriented:", "options": [ "Along the long axis of the ulna", "Along the long axis of the scaphoid", "Perpendicular to the radial shaft only", "In the true axial plane only" ], "answer_index": 1, "explanation": "Reformations aligned with the obliquely oriented scaphoid show fracture lines, displacement and humpback deformity most clearly.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "When CT is performed for suspected tarsal coalition, the feet are usually scanned:", "options": [ "Unilaterally, to halve the dose", "Only after intra-articular contrast", "Only in the sagittal plane", "Bilaterally, for side-to-side comparison" ], "answer_index": 3, "explanation": "Coalition is often bilateral, so both feet are scanned together; coronal reformations best show talocalcaneal coalition.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A modified Valsalva maneuver during neck CT is used mainly to distend the:", "options": [ "Parotid ducts", "Pyriform sinuses", "Sphenoid sinus", "Nasopharynx" ], "answer_index": 1, "explanation": "Increasing pressure against a closed mouth and nose distends the hypopharynx so the pyriform sinuses and aryepiglottic folds can be evaluated.", "subcategory": "Neck and Chest" }, { "q": "On neck CTA, the common carotid artery typically bifurcates at approximately which level?", "options": [ "C6–C7", "C3–C4", "T1–T2", "C1–C2" ], "answer_index": 1, "explanation": "The carotid bifurcation usually lies at C3–C4, a key landmark for stenosis evaluation, though it varies between patients.", "subcategory": "Neck and Chest" }, { "q": "Dental amalgam is producing streaks over the oral cavity on a soft-tissue neck CT. A common technique to reduce this is to:", "options": [ "Add an angled block through the oral cavity avoiding the fillings", "Reduce the mAs by half when scanning the oral cavity", "Narrow the window width when the images are viewed", "Lower the kVp to 80 for the entire neck acquisition" ], "answer_index": 0, "explanation": "Angling the gantry (or the patient's head) moves the fillings out of the plane of interest; MAR software can also help.", "subcategory": "Neck and Chest" }, { "q": "Which postprocessing display gives an endoluminal 3D view of a tracheal stenosis?", "options": [ "Virtual bronchoscopy", "Shaded surface display of the spine", "Curved reformation of the aorta", "Maximum intensity projection" ], "answer_index": 0, "explanation": "Virtual bronchoscopy uses volume rendering from inside the airway; MinIP and MPRs are also used to display airway narrowing.", "subcategory": "Neck and Chest" }, { "q": "Expiratory images are added to an HRCT of the chest mainly to detect:", "options": [ "Pulmonary embolism", "Pleural calcification", "Air trapping", "Hilar adenopathy" ], "answer_index": 2, "explanation": "Areas of small-airways disease fail to lose air on expiration and stay relatively lucent, producing mosaic attenuation.", "subcategory": "Neck and Chest" }, { "q": "For a prospectively triggered coronary CTA in a patient with a heart rate of 58 bpm, the exposure window is usually centered at about:", "options": [ "0–10% of the R-R interval", "100% of the R-R interval", "70–75% of the R-R interval (mid-diastole)", "30–40% of the R-R interval at all heart rates" ], "answer_index": 2, "explanation": "At low heart rates, mid-to-late diastole is the period of least coronary motion; end-systole (about 35–45%) may be chosen at higher rates.", "subcategory": "Neck and Chest" }, { "q": "Which patient should NOT receive IV metoprolol before coronary CTA?", "options": [ "An anxious patient with normal vital signs", "A patient with a heart rate of 78 bpm and normal blood pressure", "A patient in an active asthma exacerbation with wheezing", "A patient taking a statin" ], "answer_index": 2, "explanation": "Beta-blockers are contraindicated with active bronchospasm, hypotension, decompensated heart failure and second- or third-degree heart block.", "subcategory": "Neck and Chest" }, { "q": "For TAVR planning, the aortic annulus is typically measured in which part of the cardiac cycle?", "options": [ "Systole, about 30–40% of the R-R interval", "End-diastole at 90%", "On the scout image", "During a noncontrast calcium-score scan" ], "answer_index": 0, "explanation": "The annulus is generally largest in systole, so sizing is done on systolic phases from a gated contrast acquisition.", "subcategory": "Neck and Chest" }, { "q": "What is the main advantage of retrospective ECG gating compared with prospective triggering?", "options": [ "It can be performed without any ECG signal", "It delivers a lower radiation dose to the patient", "It allows the coronaries to be seen without contrast", "Data from every phase allow functional and valve analysis" ], "answer_index": 3, "explanation": "Continuous low-pitch helical scanning records the whole cardiac cycle, allowing multiphase reconstructions at the cost of a higher dose.", "subcategory": "Neck and Chest" }, { "q": "ECG gating is used for CT angiography of the thoracic aorta mainly to:", "options": [ "Remove aortic root pulsation artifact that mimics a flap", "Avoid the need for any IV contrast administration", "Allow a lower kVp to be used for every patient", "Improve visualization of the lung parenchyma" ], "answer_index": 0, "explanation": "Motion of the ascending aorta can produce a curvilinear artifact resembling an intimal flap; gating freezes this motion.", "subcategory": "Neck and Chest" }, { "q": "Which anterior mediastinal structure is normally prominent in children and young adults and involutes with age?", "options": [ "Descending aorta", "Esophagus", "Azygos vein", "Thymus" ], "answer_index": 3, "explanation": "The thymus occupies the anterior mediastinum and is gradually replaced by fat in adulthood.", "subcategory": "Neck and Chest" }, { "q": "Findings on a low-dose lung cancer screening CT are categorized using which system?", "options": [ "BI-RADS", "TI-RADS", "Lung-RADS", "LI-RADS" ], "answer_index": 2, "explanation": "The ACR's Lung-RADS standardizes reporting and follow-up recommendations for screening CT.", "subcategory": "Neck and Chest" }, { "q": "According to ACR/STR guidance, a low-dose lung cancer screening CT should be set to produce a CTDIvol for a standard-sized patient of:", "options": [ "3 mGy or less", "10 mGy or less", "1 mSv or less", "25 mGy or less" ], "answer_index": 0, "explanation": "The ACR–STR practice parameter and CMS coverage call for a CTDIvol of ≤3 mGy for a standard-sized patient (about 170 cm, 70 kg), adjusted for size.", "subcategory": "Neck and Chest" }, { "q": "For CT esophagography in suspected esophageal perforation, oral contrast is given as:", "options": [ "Thick barium paste given about 1 hour before scanning", "No oral contrast; IV contrast is given on its own", "Dilute water-soluble contrast swallowed just before scanning", "Plain water given 45 minutes before the scan begins" ], "answer_index": 2, "explanation": "Contrast must be in the esophagus at the time of scanning so leaks can be seen; water-soluble agents are used when perforation is suspected.", "subcategory": "Neck and Chest" }, { "q": "For a contrast-enhanced chest CTA, the right arm is often preferred for IV access because:", "options": [ "The right arm veins drain directly into the IVC", "Right arm veins are larger than left arm veins in all patients", "It avoids dense contrast in the left brachiocephalic vein", "It shortens the total scan acquisition time" ], "answer_index": 2, "explanation": "Contrast from the left arm crosses the mediastinum in the left brachiocephalic vein, where dense undiluted contrast creates streaks over the aortic arch and its branches.", "subcategory": "Neck and Chest" }, { "q": "On chest CT for pectus excavatum, the Haller index is calculated by dividing the:", "options": [ "Transverse heart width by the transverse inner chest width", "Sternal length by the length of the thoracic spine", "Sternum-to-spine distance by the inner transverse chest width", "Inner transverse chest width by the sternum-to-spine distance" ], "answer_index": 3, "explanation": "A Haller index above about 3.25 is commonly used as a threshold for severe pectus excavatum.", "subcategory": "Neck and Chest" }, { "q": "When indirect CT venography of the legs is added to a CT pulmonary angiogram, the venous images are acquired:", "options": [ "After a second full-volume contrast injection", "About 3–4 minutes after injection, with no added contrast", "About 24 hours later, after the contrast has cleared", "Immediately after the pulmonary arterial phase, at 15 s" ], "answer_index": 1, "explanation": "Waiting several minutes allows the same contrast bolus to opacify the pelvic and leg veins so DVT can be seen as a filling defect.", "subcategory": "Neck and Chest" }, { "q": "In the late arterial phase, the spleen shows a heterogeneous zebra-striped pattern. This means:", "options": [ "A splenic laceration that needs urgent surgical review", "Splenic infarction from an embolus to the splenic artery", "Contrast extravasation from active splenic hemorrhage", "A normal early pattern; the spleen is judged on portal venous images" ], "answer_index": 3, "explanation": "Differential flow through the red and white pulp causes normal heterogeneous enhancement early on, which becomes uniform by the portal venous phase.", "subcategory": "Abdomen and Pelvis" }, { "q": "An adrenal nodule measures 20 HU unenhanced, 110 HU at 60 seconds and 50 HU at 15 minutes. What is the absolute washout, and what does it suggest?", "options": [ "120%, an invalid calculation", "55%, which is indeterminate", "67%, consistent with an adenoma", "45%, suggesting a metastasis" ], "answer_index": 2, "explanation": "Absolute washout = (110 − 50) ÷ (110 − 20) × 100 ≈ 67%; a value of 60% or more supports an adenoma.", "subcategory": "Abdomen and Pelvis" }, { "q": "In acute pancreatitis, contrast-enhanced CT to assess pancreatic necrosis is most accurate when performed:", "options": [ "Within the first 6 hours", "At least 72 hours after symptom onset", "Before any clinical diagnosis is made", "Only without IV contrast" ], "answer_index": 1, "explanation": "Necrosis may not be apparent early, so CT for complications is best done after about 72 hours unless the diagnosis is unclear.", "subcategory": "Abdomen and Pelvis" }, { "q": "The portal vein is formed behind the neck of the pancreas by the union of the:", "options": [ "Superior mesenteric vein and splenic vein", "Inferior mesenteric vein and left renal vein", "Inferior vena cava and renal vein", "Hepatic veins and IVC" ], "answer_index": 0, "explanation": "The SMV and splenic vein join posterior to the pancreatic neck, a key landmark when staging pancreatic tumors.", "subcategory": "Abdomen and Pelvis" }, { "q": "In which renal phase is the cortex markedly brighter than the medulla?", "options": [ "Nephrographic phase (about 90–100 s)", "Corticomedullary phase (about 25–40 s)", "Excretory phase (about 5–10 min)", "Noncontrast phase" ], "answer_index": 1, "explanation": "Early after injection, contrast fills the cortex before the medulla; small medullary lesions can be missed in this phase.", "subcategory": "Abdomen and Pelvis" }, { "q": "A split-bolus CT urogram is used to:", "options": [ "Image the kidneys only in the arterial phase", "Allow the exam to proceed without any patient hydration", "Eliminate the need for IV contrast in hematuria evaluation", "Show parenchyma and collecting system in one scan, reducing dose" ], "answer_index": 3, "explanation": "Giving contrast in two portions with a delay between them lets one scan show both parenchymal enhancement and an opacified collecting system.", "subcategory": "Abdomen and Pelvis" }, { "q": "A patient taking the protease inhibitor indinavir has suspected renal colic. Why does this matter for stone CT?", "options": [ "IV contrast is required to see all stones", "Uric acid stones are invisible on CT", "Calcium oxalate stones cannot be detected on CT", "Indinavir stones may be invisible on CT" ], "answer_index": 3, "explanation": "Nearly all stones, including uric acid stones, are dense on CT, but pure indinavir stones can be radiolucent, so only secondary signs such as hydronephrosis may be seen.", "subcategory": "Abdomen and Pelvis" }, { "q": "When searching for the appendix on CT, the technologist should know it arises from the:", "options": [ "Cecum, inferior to the ileocecal valve", "Terminal ileum above the valve", "Sigmoid colon", "Ascending colon at the hepatic flexure" ], "answer_index": 0, "explanation": "The appendix originates from the posteromedial cecum below the ileocecal valve, although its tip position varies.", "subcategory": "Abdomen and Pelvis" }, { "q": "Positive oral contrast is avoided for CT angiography in acute GI bleeding because it:", "options": [ "Dilutes the IV contrast within the arteries", "Prevents accurate arterial-phase bolus timing", "Would hide extravasated IV contrast in the bowel", "Causes the patient to vomit blood during the scan" ], "answer_index": 2, "explanation": "Active bleeding appears as high-attenuation IV contrast pooling in the bowel; dense oral contrast would make this impossible to distinguish.", "subcategory": "Abdomen and Pelvis" }, { "q": "CT enterography uses neutral oral contrast (water or low-density barium) mainly to:", "options": [ "Show bowel wall enhancement and thickening", "Tag residual stool for colonic polyp detection", "Avoid the need for IV contrast administration", "Make the bowel lumen brighter than the wall" ], "answer_index": 0, "explanation": "Neutral luminal contrast distends the bowel and contrasts with enhancing mucosa, which is key in assessing Crohn's disease activity.", "subcategory": "Abdomen and Pelvis" }, { "q": "The celiac trunk usually arises from the aorta at about T12–L1. Its three main branches are the:", "options": [ "Right and left renal and gonadal arteries", "Left gastric, splenic and common hepatic arteries", "Superior mesenteric, inferior mesenteric and splenic arteries", "Gastroduodenal, right gastric and cystic arteries" ], "answer_index": 1, "explanation": "The celiac trunk supplies the foregut through the left gastric, splenic and common hepatic arteries; the SMA arises just below it.", "subcategory": "Abdomen and Pelvis" }, { "q": "After endovascular aneurysm repair (EVAR), follow-up CT includes delayed images mainly to:", "options": [ "Reduce stent-graft metal artifact", "Detect slow-filling endoleaks", "Evaluate bowel peristalsis", "Measure renal contrast excretion" ], "answer_index": 1, "explanation": "Some endoleaks (for example, type II from lumbar or inferior mesenteric arteries) fill slowly and are seen only on delayed phases.", "subcategory": "Abdomen and Pelvis" }, { "q": "A liver lesion shows peripheral, nodular, discontinuous enhancement in the arterial phase that progressively fills in on delayed images. This is typical of:", "options": [ "Hepatocellular carcinoma", "Simple cyst", "Hemangioma", "Hepatic steatosis" ], "answer_index": 2, "explanation": "Centripetal fill-in of peripheral nodular enhancement is the classic pattern of a cavernous hemangioma; HCC typically shows arterial enhancement with washout.", "subcategory": "Abdomen and Pelvis" }, { "q": "To evaluate a suspected anastomotic leak after a low anterior resection, contrast is best administered:", "options": [ "Orally, as barium 2 hours before", "Intravenously, with no other contrast", "Rectally, as dilute water-soluble contrast", "Intrathecally, via lumbar puncture" ], "answer_index": 2, "explanation": "Rectal water-soluble contrast fills the distal colon and anastomosis directly so a leak appears as extraluminal contrast.", "subcategory": "Abdomen and Pelvis" }, { "q": "In CT colonography, fecal tagging with oral barium or iodine is used to:", "options": [ "Distend the colon", "Distinguish residual stool from polyps", "Increase colonic peristalsis", "Replace the need for prone imaging" ], "answer_index": 1, "explanation": "Tagged stool becomes dense and is easily separated from soft-tissue polyps, which do not take up the tagging agent.", "subcategory": "Abdomen and Pelvis" }, { "q": "In a supine female patient, small amounts of free pelvic fluid first collect in the:", "options": [ "Retropubic space (of Retzius)", "Rectouterine pouch", "Right subphrenic space", "Vesicouterine pouch" ], "answer_index": 1, "explanation": "The rectouterine pouch is the most dependent part of the female peritoneal cavity.", "subcategory": "Abdomen and Pelvis" }, { "q": "On male pelvis CT, the seminal vesicles are located:", "options": [ "Posterior to the bladder and superior to the prostate", "Inferior to the prostate, within the scrotum", "Anterior to the bladder, behind the pubic symphysis", "Lateral to the iliac wings, near the hip joints" ], "answer_index": 0, "explanation": "The paired seminal vesicles lie between the posterior bladder wall and the rectum, just above the prostate base.", "subcategory": "Abdomen and Pelvis" }, { "q": "For a CT-guided biopsy of a native kidney, the patient is usually positioned:", "options": [ "Prone", "Trendelenburg", "Upright", "Supine" ], "answer_index": 0, "explanation": "The kidneys are retroperitoneal, so a prone posterior approach avoids bowel and other organs.", "subcategory": "Abdomen and Pelvis" }, { "q": "On trauma CT, the sentinel clot sign refers to:", "options": [ "Low-attenuation simple fluid in the pelvis", "Free intraperitoneal air beneath the diaphragm", "Densest clotted blood next to the bleeding organ", "Excreted contrast in the renal collecting system" ], "answer_index": 2, "explanation": "Clotted blood (about 45–70 HU) accumulates densest near its source, helping locate the injured organ.", "subcategory": "Abdomen and Pelvis" }, { "q": "For a suspected deep neck abscess, IV contrast is given mainly to show:", "options": [ "Calcified lymph nodes within the posterior triangle", "A fluid collection with a rim of peripheral enhancement", "Air in the trachea above the thoracic inlet", "Bony erosion of the hyoid on bone windows" ], "answer_index": 1, "explanation": "An abscess appears as a low-density collection with an enhancing wall, separating it from phlegmon or cellulitis.", "subcategory": "Neck and Chest" }, { "q": "A tripod fracture of the face, now called a zygomaticomaxillary complex fracture, primarily involves:", "options": [ "The zygoma and its articulations", "The pterygoid plates and palate", "The nasal bones and septum only", "The mandibular condyles" ], "answer_index": 0, "explanation": "The zygoma is separated at its frontal, maxillary, temporal and sphenoid connections; 3D and coronal images aid repair planning.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "For a dedicated pituitary (sella) CT, the most useful thin-section reformations are in which plane?", "options": [ "Axial", "Sagittal", "Oblique", "Coronal" ], "answer_index": 3, "explanation": "Coronal images show the gland, stalk, optic chiasm and cavernous sinuses together, so they are the key sella plane.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "When a kidney laceration is seen on trauma CT, delayed excretory-phase images help identify:", "options": [ "Urine leaking from a collecting system injury", "Active arterial bleeding from a renal laceration", "Thrombosis of the main renal vein", "Calcified stones within the renal pelvis" ], "answer_index": 0, "explanation": "Delayed images at several minutes opacify the collecting system so extravasated urine can be seen.", "subcategory": "Abdomen and Pelvis" }, { "q": "On a head CTA, which vessels connect the anterior (carotid) and posterior (vertebrobasilar) circulations in the circle of Willis?", "options": [ "Anterior communicating artery", "Superior cerebellar arteries", "Posterior communicating arteries", "Anterior choroidal arteries" ], "answer_index": 2, "explanation": "The posterior communicating arteries join the internal carotids to the posterior cerebral arteries; the anterior communicating artery joins the two ACAs.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Before coronary CTA, oral or IV beta-blockers are commonly given to bring the heart rate to about:", "options": [ "60–65 bpm or lower", "80–90 bpm", "95–105 bpm", "40 bpm or lower" ], "answer_index": 0, "explanation": "A slow, regular rate lengthens diastole and reduces motion, allowing prospective triggering and lower dose.", "subcategory": "Neck and Chest" }, { "q": "The uncinate process of the pancreas normally lies:", "options": [ "Anterior to the superior mesenteric artery", "Lateral to the second part of the duodenum", "Posterior to the superior mesenteric vein", "Superior to the splenic vein near the hilum" ], "answer_index": 2, "explanation": "The uncinate process hooks behind the SMV; loss of the fat plane there matters for pancreatic cancer staging.", "subcategory": "Abdomen and Pelvis" }, { "q": "A 4D CT for a suspected parathyroid adenoma relies mainly on:", "options": [ "A single delayed phase acquired 10 minutes after contrast", "Noncontrast images that show calcium within the adenoma", "Oral contrast to separate the adenoma from the esophagus", "Multiphase imaging showing avid early enhancement and washout" ], "answer_index": 3, "explanation": "Parathyroid adenomas typically enhance strongly in the arterial phase and wash out, distinguishing them from nodes and thyroid.", "subcategory": "Neck and Chest" }, { "q": "To quantify glenoid bone loss in a patient with recurrent shoulder dislocation, the most useful CT display is:", "options": [ "An axial MIP of the whole shoulder girdle in a bone window", "An en face 3D view of the glenoid with the humeral head removed", "A curved reformation along the long head of the biceps tendon", "A coronal soft-tissue reformation through the rotator cuff" ], "answer_index": 1, "explanation": "Subtracting the humeral head and viewing the glenoid face-on allows accurate measurement of anterior rim bone loss.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A triple rule-out CT in an emergency department patient with chest pain evaluates the:", "options": [ "Coronary arteries, thoracic aorta and pulmonary arteries", "Coronary arteries, carotid arteries and the abdominal aorta", "Pulmonary veins, esophagus and the superior vena cava", "Thoracic aorta, renal arteries and the iliac arteries" ], "answer_index": 0, "explanation": "This ECG-gated protocol times contrast to opacify both left and right circulations for coronary disease, dissection and PE.", "subcategory": "Neck and Chest" }, { "q": "Sinus CT intended for an intraoperative image-guided navigation system must generally be acquired:", "options": [ "As thick 5 mm slices with a soft-tissue kernel and wide spacing", "As thin contiguous axial slices, without gantry tilt, per vendor protocol", "As coronal direct images with the head hyperextended in the gantry", "With IV contrast and a 15-degree gantry tilt to protect the lens" ], "answer_index": 1, "explanation": "Navigation software registers a continuous volume, so it needs thin, untilted, contiguous data with fiducial or surface coverage.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Which technique defines high-resolution CT (HRCT) of the lungs?", "options": [ "Thick sections reconstructed with a smooth soft-tissue kernel", "Thin sections reconstructed with a sharp, high-frequency kernel", "IV contrast given in the arterial phase with bolus tracking", "A low-kVp acquisition reconstructed in a mediastinal window" ], "answer_index": 1, "explanation": "HRCT uses about 1 mm or thinner slices with an edge-enhancing kernel to show interstitial and small airway detail.", "subcategory": "Neck and Chest" }, { "q": "For a pancreas-protocol CT, the pancreatic parenchymal (late arterial) phase is typically acquired at about:", "options": [ "15–20 seconds after injection", "90–120 seconds after injection", "40–50 seconds after injection", "5–10 minutes after injection" ], "answer_index": 2, "explanation": "Peak pancreatic enhancement around 40–50 s gives the most contrast between a hypoenhancing adenocarcinoma and normal gland.", "subcategory": "Abdomen and Pelvis" }, { "q": "Compared with ultrasound for suspected gallstones, CT:", "options": [ "Detects nearly all gallstones regardless of composition", "May miss stones that match the attenuation of bile", "Is preferred because gallstones are always calcified", "Requires positive oral contrast to show any gallstone" ], "answer_index": 1, "explanation": "Many cholesterol stones are isoattenuating to bile and invisible on CT, so ultrasound remains first-line.", "subcategory": "Abdomen and Pelvis" }, { "q": "A biconvex (lens-shaped) extra-axial collection on head CT that does not cross the cranial sutures is most consistent with:", "options": [ "An epidural hematoma", "A subdural hematoma", "A subarachnoid hemorrhage", "An intraventricular hemorrhage" ], "answer_index": 0, "explanation": "Epidural blood is limited by the dural attachments at the sutures, giving a biconvex shape, often with a skull fracture.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Dual-energy CT of the feet can support a diagnosis of gout by color-coding:", "options": [ "Calcium pyrophosphate in cartilage", "Bone marrow edema around joints", "Iodine enhancement of the synovium", "Monosodium urate crystal deposits" ], "answer_index": 3, "explanation": "Material decomposition separates urate from calcium, so tophaceous deposits can be shown and quantified without contrast.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "The Sanders classification of intra-articular calcaneal fractures is based on which CT images?", "options": [ "Coronal (semicoronal) images perpendicular to the posterior facet", "Axial images parallel to the plantar surface of the foot", "Sagittal images through the middle of the talar dome", "3D surface renderings of the entire hindfoot only" ], "answer_index": 0, "explanation": "Sanders uses the widest view of the posterior subtalar facet on semicoronal images to count articular fracture lines.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "In Western adult patients, diverticulitis on abdominal CT most often involves the:", "options": [ "Ascending colon", "Transverse colon", "Sigmoid colon", "Splenic flexure" ], "answer_index": 2, "explanation": "Left-sided, especially sigmoid, diverticular disease predominates in Western populations; right-sided disease is more common in Asian populations.", "subcategory": "Abdomen and Pelvis" }, { "q": "On a lateral lumbar localizer, the top of the iliac crests usually corresponds to approximately:", "options": [ "The T12–L1 level", "The L2–L3 level", "The L4–L5 level", "The S1–S2 level" ], "answer_index": 2, "explanation": "The iliac crests are a common landmark for the L4 vertebra and L4–L5 interspace when planning lumbar spine scans.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "Which vertebral body usually lies at the same level as the cricoid cartilage on a soft-tissue neck CT?", "options": [ "C3", "C4", "C6", "T2" ], "answer_index": 2, "explanation": "The hyoid lies near C3, the thyroid cartilage around C4–C5, and the cricoid at C6.", "subcategory": "Neck and Chest" }, { "q": "The left renal vein normally reaches the IVC by passing:", "options": [ "Posterior to the aorta, above the celiac trunk", "Anterior to the aorta, just below the SMA origin", "Anterior to the SMA, alongside the splenic vein", "Posterior to the IVC, behind the right crus" ], "answer_index": 1, "explanation": "The left renal vein crosses between the SMA and aorta; a retroaortic or circumaortic vein is an important variant before surgery.", "subcategory": "Abdomen and Pelvis" }, { "q": "An abdominal aortic aneurysm is generally defined as an infrarenal aortic diameter of:", "options": [ "3.0 cm or greater", "1.5 cm or greater", "2.0 cm or greater", "5.5 cm or greater" ], "answer_index": 0, "explanation": "An infrarenal aorta of 3 cm or more is aneurysmal; about 5.5 cm is a common threshold for elective repair in men.", "subcategory": "Abdomen and Pelvis" }, { "q": "In a patient with right-dominant coronary circulation, the posterior descending artery arises from the:", "options": [ "Left anterior descending artery", "Left main coronary artery", "First diagonal branch", "Right coronary artery" ], "answer_index": 3, "explanation": "Dominance is defined by which artery supplies the PDA; most people are right dominant.", "subcategory": "Neck and Chest" }, { "q": "On a cardiac CT, a filling defect is seen in the left atrial appendage. Which addition best distinguishes thrombus from slow-flow mixing?", "options": [ "A repeat arterial scan with a faster injection rate", "Reconstruction with a sharper kernel and thinner slices", "A noncontrast scan through the appendage before injection", "A delayed acquisition through the appendage about a minute later" ], "answer_index": 3, "explanation": "Slow flow fills in on delayed images, whereas a true thrombus persists as a filling defect.", "subcategory": "Neck and Chest" }, { "q": "Acute clotted blood within the brain on a noncontrast head CT typically measures about:", "options": [ "0–15 HU", "50–80 HU", "150–250 HU", "−50 to −20 HU" ], "answer_index": 1, "explanation": "Fresh clot is hyperattenuating to brain (about 30–40 HU) because of its protein content; it becomes less dense over days to weeks.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A CT angiogram for a potential living kidney donor is performed mainly to show:", "options": [ "The excretion rate of each kidney over 24 hours", "The number and course of renal arteries and veins", "Bladder wall thickness and residual urine volume", "Adrenal washout values on 15-minute delayed images" ], "answer_index": 1, "explanation": "Surgeons need to know about accessory renal arteries, early branching and venous variants before donor nephrectomy.", "subcategory": "Abdomen and Pelvis" }, { "q": "On noncontrast CT, hepatic steatosis is suggested when the liver measures:", "options": [ "At least 10 HU higher than the spleen", "The same attenuation as the kidney", "At least 10 HU lower than the spleen", "Above 75 HU throughout the parenchyma" ], "answer_index": 2, "explanation": "Normal liver is slightly denser than spleen; fat lowers liver attenuation, so a liver well below spleen indicates steatosis.", "subcategory": "Abdomen and Pelvis" }, { "q": "For suspected acute mesenteric ischemia, a typical CT protocol uses:", "options": [ "A single delayed phase at 5 minutes with positive oral contrast", "Noncontrast low-dose images only, as for a kidney stone exam", "Positive rectal contrast and a single portal venous phase", "Arterial and portal venous phases with neutral or no oral contrast" ], "answer_index": 3, "explanation": "Arterial images show SMA occlusion, venous images show mesenteric venous thrombosis and bowel wall, and positive oral contrast would obscure wall enhancement.", "subcategory": "Abdomen and Pelvis" }, { "q": "A Jefferson fracture seen on cervical spine CT is a fracture of the:", "options": [ "Pars of C2 (axis)", "Dens of C2 (odontoid)", "Spinous process of C7", "Ring of C1 (atlas)" ], "answer_index": 3, "explanation": "A Jefferson fracture is a burst of the C1 ring from axial loading; bilateral C2 pars fractures are hangman's fractures.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "In a thoracolumbar burst fracture, CT is especially valuable for demonstrating:", "options": [ "Retropulsed bone fragments narrowing the spinal canal", "Spinal cord edema and ligament signal changes", "Early marrow edema in an occult compression injury", "Nerve root compression from a soft disc herniation" ], "answer_index": 0, "explanation": "CT excels at bony detail, showing posterior displacement of vertebral body fragments into the canal; cord and ligaments are MRI territory.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "A minimum intensity projection (MinIP) of the chest is most useful for displaying:", "options": [ "Calcified coronary plaque and stent struts", "Contrast-filled pulmonary arteries and emboli", "Airways and areas of emphysema or air trapping", "Small solid nodules hidden among vessels" ], "answer_index": 2, "explanation": "MinIP shows the lowest-attenuation voxel along each ray, highlighting air-containing structures.", "subcategory": "Neck and Chest" }, { "q": "3D volume-rendered images of the skull in an infant are often requested to evaluate:", "options": [ "Acute subarachnoid hemorrhage", "Premature fusion of the cranial sutures", "Middle ear ossicle dislocation", "Pituitary microadenoma" ], "answer_index": 1, "explanation": "Craniosynostosis is evaluated with low-dose head CT and 3D renderings that display the sutures and skull shape.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "To detect a small amount of free intraperitoneal air on abdominal CT, the images are best reviewed in:", "options": [ "A lung or wide window", "A narrow brain window", "A standard liver window", "A soft-tissue MIP" ], "answer_index": 0, "explanation": "A wide window separates tiny gas bubbles from fat, which can look similarly dark in a soft-tissue window.", "subcategory": "Abdomen and Pelvis" }, { "q": "The most common complication after a CT-guided percutaneous lung biopsy is:", "options": [ "Air embolism", "Pneumothorax", "Tumor seeding", "Hemothorax" ], "answer_index": 1, "explanation": "Pneumothorax is by far the most common complication, so post-procedure images and observation are routine; air embolism is rare.", "subcategory": "Neck and Chest" }, { "q": "A delayed (equilibrium) phase at about 3–5 minutes in a multiphase liver CT mainly helps show:", "options": [ "Peak arterial enhancement of hypervascular metastases", "Excretion of contrast into the biliary tree", "The first pass of contrast through the portal vein", "Washout and capsule appearance of hepatocellular carcinoma" ], "answer_index": 3, "explanation": "HCC enhances in the arterial phase and becomes hypoattenuating with an enhancing capsule on portal venous or delayed images.", "subcategory": "Abdomen and Pelvis" }, { "q": "A cardiac CT before atrial fibrillation ablation is performed mainly to map the:", "options": [ "Coronary sinus and right atrium", "Tricuspid valve and right ventricle", "Pulmonary veins and left atrium", "Internal mammary arteries" ], "answer_index": 2, "explanation": "Ablation targets the pulmonary vein ostia, so the number, size and drainage of the pulmonary veins and left atrial anatomy are mapped.", "subcategory": "Neck and Chest" }, { "q": "Cystic renal masses on CT are categorized for management using the:", "options": [ "Lung-RADS classification", "Bosniak classification", "Sanders classification", "LI-RADS classification" ], "answer_index": 1, "explanation": "Bosniak categories (I–IV) use wall, septa, calcification and enhancement to estimate the likelihood of malignancy.", "subcategory": "Abdomen and Pelvis" }, { "q": "A Stanford type A aortic dissection is defined by involvement of the:", "options": [ "Ascending aorta", "Abdominal aorta only", "Left subclavian artery only", "Descending thoracic aorta only" ], "answer_index": 0, "explanation": "Any dissection involving the ascending aorta is type A, usually a surgical emergency; type B spares it.", "subcategory": "Neck and Chest" }, { "q": "On a FAST-positive trauma patient's CT, upper abdominal hemoperitoneum is most often first seen in the:", "options": [ "Hepatorenal recess (Morison's pouch)", "Lesser sac behind the stomach", "Left paracolic gutter", "Retropubic space of Retzius" ], "answer_index": 0, "explanation": "Morison's pouch, between the liver and right kidney, is the most dependent part of the supramesocolic space when supine.", "subcategory": "Abdomen and Pelvis" }, { "q": "In the Couinaud system of liver segments, the caudate lobe is segment:", "options": [ "IV", "V", "VIII", "I" ], "answer_index": 3, "explanation": "The caudate lobe is segment I and has its own venous drainage directly into the IVC.", "subcategory": "Abdomen and Pelvis" }, { "q": "After facial trauma, an orbital floor (blowout) fracture with herniation of fat into the maxillary sinus is best seen on:", "options": [ "Coronal reformations", "Axial source images", "Curved reformations", "Minimum intensity projections" ], "answer_index": 0, "explanation": "The orbital floor is a horizontal plate, so it is seen in cross-section on coronal images.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "On a noncontrast head CT for acute stroke, a hyperdense middle cerebral artery sign suggests:", "options": [ "Calcified atherosclerosis of the carotid siphon", "Hemorrhagic conversion of an old infarct", "Thrombus within the middle cerebral artery", "Normal flowing blood with a high hematocrit only" ], "answer_index": 2, "explanation": "Increased density in the course of the MCA reflects acute clot and supports large-vessel occlusion; CTA usually follows.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "The superior mesenteric artery usually arises from the anterior aorta at about:", "options": [ "T10, roughly 3 cm above the celiac trunk", "L3, at the level of the inferior mesenteric artery", "L4, just above the aortic bifurcation", "L1, roughly 1 cm below the celiac trunk" ], "answer_index": 3, "explanation": "The SMA originates about 1 cm below the celiac trunk at L1; the IMA arises near L3.", "subcategory": "Abdomen and Pelvis" }, { "q": "On chest CT, the azygos vein arches forward over which structure to drain into the superior vena cava?", "options": [ "The left main bronchus", "The aortic arch", "The left pulmonary artery", "The right main bronchus" ], "answer_index": 3, "explanation": "The azygos arch passes over the right main bronchus at about T4 to join the posterior SVC.", "subcategory": "Neck and Chest" }, { "q": "Which contrast agent is appropriate for intrathecal injection before CT myelography?", "options": [ "A high-osmolality ionic agent such as diatrizoate meglumine", "A nonionic agent labeled for intrathecal use, such as iohexol", "A gadolinium-based agent at the standard intravenous dose", "A dilute barium sulfate suspension made for oral use" ], "answer_index": 1, "explanation": "Only specific nonionic iodinated agents are approved intrathecally; ionic iodinated contrast given intrathecally can cause seizures and death.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "With typical anatomy, the first branch arising from the aortic arch is the:", "options": [ "Left common carotid artery", "Brachiocephalic trunk", "Left subclavian artery", "Right vertebral artery" ], "answer_index": 1, "explanation": "From right to left the arch gives off the brachiocephalic trunk, left common carotid and left subclavian arteries.", "subcategory": "Neck and Chest" }, { "q": "Quantitative CT (QCT) for bone mineral density requires:", "options": [ "Dual-source acquisition at two different rotation times", "IV contrast to enhance the trabecular bone of the spine", "A calibration phantom of known density scanned with the patient", "A sharp bone kernel at the thinnest available slice" ], "answer_index": 2, "explanation": "QCT converts trabecular bone CT numbers into mineral density using a reference phantom placed under the patient.", "subcategory": "Head, Spine, and Musculoskeletal" }, { "q": "On coronary CTA, which artery runs in the anterior interventricular groove?", "options": [ "Right coronary artery", "Left circumflex artery", "Left anterior descending artery", "Posterior descending artery" ], "answer_index": 2, "explanation": "The LAD courses in the anterior interventricular groove toward the apex, supplying the anterior wall and septum.", "subcategory": "Neck and Chest" }, { "q": "To evaluate suspected tracheomalacia, chest CT adds:", "options": [ "Dynamic or end-expiratory images to show airway collapse", "Delayed contrast images of the tracheal wall at 3 minutes", "Prone inspiratory images through the lung bases only", "Thick-slice MIPs of the pulmonary arteries" ], "answer_index": 0, "explanation": "Excessive narrowing of the tracheal lumen during expiration, compared with inspiration, indicates tracheomalacia.", "subcategory": "Neck and Chest" }, { "q": "On a neck CTA, the vertebral arteries typically ascend through the:", "options": [ "Intervertebral foramina of C7 through C3", "Carotid sheath alongside the jugular vein", "Spinal canal anterior to the spinal cord", "Transverse foramina of C6 through C1" ], "answer_index": 3, "explanation": "Each vertebral artery usually enters the C6 transverse foramen and ascends through C1 before entering the skull at the foramen magnum.", "subcategory": "Head, Spine, and Musculoskeletal" } ] } ], "body_regions": [ { "region": "head", "label": "Head / Brain", "common_exams": [ "Noncontrast head (stroke, trauma)", "CT perfusion and CTA head", "Sinuses", "Temporal bones / IAC", "Orbits", "Maxillofacial and mandible", "TMJs" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/5/57/Ct-scan_of_the_brain_with_an_subdural_hematoma.jpg", "caption": "Axial noncontrast head CT showing a crescent-shaped subdural hematoma along the cerebral convexity (arrows).", "credit": "Lucien Monfils", "license": "CC BY-SA 3.0", "page_url": "https://commons.wikimedia.org/wiki/File:Ct-scan_of_the_brain_with_an_subdural_hematoma.jpg" }, "questions": [ { "q": "The image shows a crescent-shaped extra-axial collection along the convexity. A collection with this shape is most consistent with:", "options": [ "Epidural hematoma", "Subdural hematoma", "Intraventricular hemorrhage", "Hydrocephalus" ], "answer_index": 1, "explanation": "Subdural blood spreads along the convexity in a crescent and can cross sutures; epidural hematomas are typically lens-shaped (biconvex)." }, { "q": "Which window setting is most typical for viewing brain parenchyma on head CT?", "options": [ "WW 1500 / WL −600", "WW 2000 / WL 500", "WW 400 / WL 40", "WW 80 / WL 40" ], "answer_index": 3, "explanation": "A narrow window around 80/40 maximizes gray–white matter contrast; 1500/−600 is a lung window and 2000/500 a bone window." }, { "q": "Which reformatted plane best demonstrates the ostiomeatal complex on sinus CT?", "options": [ "Coronal", "Axial", "Sagittal", "Oblique axial through the orbits" ], "answer_index": 0, "explanation": "Coronal images display the sinus drainage pathways and are the standard plane for evaluating the ostiomeatal complex." } ] }, { "region": "neck", "label": "Neck / Larynx / Airway", "common_exams": [ "Soft-tissue neck with IV contrast", "Larynx / airway", "CTA neck (carotid and vertebral)" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/thumb/2/20/Tonsil_oropharyngeal_SCC_CT_transverse.jpg/960px-Tonsil_oropharyngeal_SCC_CT_transverse.jpg", "caption": "Contrast-enhanced axial neck CT at the oropharynx showing an enhancing right tonsillar squamous cell carcinoma (annotated).", "credit": "Michael Goodyear", "license": "CC BY-SA 4.0", "page_url": "https://commons.wikimedia.org/wiki/File:Tonsil_oropharyngeal_SCC_CT_transverse.jpg" }, "questions": [ { "q": "A routine contrast-enhanced soft-tissue neck CT typically covers from the:", "options": [ "Vertex to the hyoid bone", "Hyoid bone to the diaphragm", "Skull base to the aortic arch", "Sella to the carina only" ], "answer_index": 2, "explanation": "Coverage from the skull base to the aortic arch includes the entire upper aerodigestive tract and the cervical lymph node chains." }, { "q": "To evaluate true vocal cord motion during a larynx CT, the patient can be asked to:", "options": [ "Take a deep breath and hold it", "Swallow repeatedly", "Phonate a prolonged \"eee\" during scanning", "Perform a forceful cough" ], "answer_index": 2, "explanation": "Phonation brings the vocal cords together so cord motion and symmetry can be assessed; quiet breathing shows them abducted." }, { "q": "Having the patient depress the shoulders during neck CT mainly helps to:", "options": [ "Reduce streak artifact from the shoulders over the lower neck", "Increase contrast enhancement", "Open the airway", "Reduce the scan length" ], "answer_index": 0, "explanation": "Lowering the shoulders moves dense bone out of the lower neck scan plane, lowering streaks and noise." } ] }, { "region": "chest", "label": "Chest / Thorax / Heart", "common_exams": [ "Routine chest with or without contrast", "CT pulmonary angiography", "Aortic dissection CTA", "HRCT", "Low-dose lung screening", "Coronary CTA and calcium scoring", "TAVR planning" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/thumb/4/4e/CT-Thorax-5.0-B70f-Lungs.jpg/960px-CT-Thorax-5.0-B70f-Lungs.jpg", "caption": "Axial chest CT at the level of the pulmonary hila displayed in a lung window (5 mm, sharp B70f kernel, 120 kV).", "credit": "Ptrump16", "license": "CC BY-SA 4.0", "page_url": "https://commons.wikimedia.org/wiki/File:CT-Thorax-5.0-B70f-Lungs.jpg" }, "questions": [ { "q": "The image is displayed in a lung window. Which setting is typical for a lung window?", "options": [ "WW 80 / WL 40", "WW 350 / WL 50", "WW 2500 / WL 800", "WW 1500 / WL −600" ], "answer_index": 3, "explanation": "A wide window centered well below zero shows aerated lung, vessels and airways; 350/50 is a mediastinal window." }, { "q": "For a CT pulmonary angiogram using bolus tracking, the monitoring ROI is usually placed in the:", "options": [ "Descending aorta", "Main pulmonary artery", "Left atrium", "Superior vena cava" ], "answer_index": 1, "explanation": "Triggering from the main pulmonary artery times the scan to peak pulmonary arterial enhancement." }, { "q": "Why are patients coached to avoid a forceful Valsalva maneuver during CT pulmonary angiography?", "options": [ "It can draw unopacified IVC blood into the right heart, causing a transient contrast interruption", "It increases the radiation dose", "It causes beam-hardening artifact in the lungs", "It slows the gantry rotation" ], "answer_index": 0, "explanation": "Deep inspiration with straining increases inflow of unenhanced IVC blood, diluting pulmonary arterial contrast and mimicking or hiding emboli." } ] }, { "region": "abdomen", "label": "Abdomen", "common_exams": [ "Routine abdomen/pelvis (portal venous)", "Multiphase liver", "Multiphase pancreas", "Adrenal protocol", "Multiphase kidneys / CT urogram", "Renal stone", "CT enterography and appendicitis" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/7/70/CT_of_a_normal_abdomen_and_pelvis%2C_axial_plane_110.png", "caption": "Contrast-enhanced axial abdominal CT at the level of the kidneys with a coronal localizer; normal anatomy (3 mm slices).", "credit": "Mikael Häggström, M.D.", "license": "CC0 1.0 (public domain dedication)", "page_url": "https://commons.wikimedia.org/wiki/File:CT_of_a_normal_abdomen_and_pelvis,_axial_plane_110.png" }, "questions": [ { "q": "A routine contrast-enhanced abdomen/pelvis CT is most commonly acquired in which phase?", "options": [ "Arterial phase, about 20 seconds", "Excretory phase, about 10 minutes", "Portal venous phase, about 60–70 seconds", "Noncontrast only" ], "answer_index": 2, "explanation": "The portal venous phase gives peak liver and bowel-wall enhancement for general survey imaging." }, { "q": "Which renal phase is best for detecting small renal masses?", "options": [ "Corticomedullary phase", "Nephrographic phase", "Excretory phase", "Noncontrast phase" ], "answer_index": 1, "explanation": "At about 90–100 seconds the parenchyma enhances uniformly, so lesions that could be hidden by corticomedullary differentiation stand out." }, { "q": "A CT exam for suspected kidney stones is typically performed:", "options": [ "With IV contrast in the arterial phase", "With positive oral contrast", "With delayed excretory images only", "Without IV or oral contrast using a low-dose technique" ], "answer_index": 3, "explanation": "Stones are dense on noncontrast CT; contrast could obscure them, and a low dose is adequate for this high-contrast task." } ] }, { "region": "pelvis", "label": "Pelvis", "common_exams": [ "Routine pelvis with abdomen", "Dedicated delayed bladder", "Retrograde CT cystogram", "Rectal contrast / colorectal", "CT colonography", "Bony pelvis and hip trauma" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/f/f5/CT_of_a_normal_abdomen_and_pelvis%2C_axial_plane_260.png", "caption": "Contrast-enhanced axial pelvic CT at the level of the femoral heads showing the urinary bladder and rectum; normal anatomy.", "credit": "Mikael Häggström, M.D.", "license": "CC0 1.0 (public domain dedication)", "page_url": "https://commons.wikimedia.org/wiki/File:CT_of_a_normal_abdomen_and_pelvis,_axial_plane_260.png" }, "questions": [ { "q": "In the image, the urinary bladder contains unopacified urine. Its expected attenuation is approximately:", "options": [ "−100 HU", "+150 to +300 HU", "−1000 HU", "0 to +20 HU" ], "answer_index": 3, "explanation": "Simple fluid such as urine measures near water; it becomes much denser only once excreted contrast reaches the bladder." }, { "q": "Delayed images for a dedicated bladder (urothelial) evaluation are obtained in the excretory phase, roughly:", "options": [ "20 seconds after injection", "5–10 minutes after injection", "35 seconds after injection", "24 hours after injection" ], "answer_index": 1, "explanation": "By several minutes, contrast has been excreted into the collecting systems and bladder, outlining filling defects." }, { "q": "For acetabular fracture surgical planning, which postprocessing is most useful?", "options": [ "Minimum intensity projection", "Thick-slab soft-tissue reconstructions only", "Thin-section MPRs and 3D volume rendering", "CT perfusion maps" ], "answer_index": 2, "explanation": "Thin multiplanar and 3D images show fracture lines and fragment displacement for the surgeon." } ] }, { "region": "spine", "label": "Spine", "common_exams": [ "Cervical spine (trauma)", "Thoracic spine", "Lumbosacral spine", "Postmyelogram CT" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/0/02/Baastrup_CT_sagittal.png", "caption": "Sagittal CT reformation of the lumbar spine in a bone window showing degenerative contact between adjacent spinous processes (Baastrup's disease, 'kissing spine').", "credit": "Hellerhoff", "license": "CC BY-SA 3.0", "page_url": "https://commons.wikimedia.org/wiki/File:Baastrup_CT_sagittal.png" }, "questions": [ { "q": "The spine image shown is displayed in which plane?", "options": [ "Sagittal", "Axial", "Coronal", "Oblique axial" ], "answer_index": 0, "explanation": "The image divides the body into right and left, showing the vertebral column in profile from front to back, which is a sagittal reformation." }, { "q": "To evaluate both bony structures and discs/soft tissues, lumbar spine CT data are routinely reconstructed with:", "options": [ "A bone kernel only", "Both a bone kernel and a soft-tissue kernel", "A lung kernel only", "A single thick-slab MIP" ], "answer_index": 1, "explanation": "Bone kernels sharpen cortical detail, while soft-tissue kernels with narrower windows show discs, the thecal sac and paraspinal tissues." }, { "q": "For cervical spine trauma CT, the scan range should include:", "options": [ "C3 through C6 only", "The vertex through C2 only", "C1 through the carina only", "The skull base (occiput) through the cervicothoracic junction (about T1–T2)" ], "answer_index": 3, "explanation": "Injuries occur at the craniocervical and cervicothoracic junctions, so both must be fully covered." } ] }, { "region": "upper_extremity", "label": "Upper Extremity / Shoulder", "common_exams": [ "Shoulder", "Elbow", "Wrist and hand", "Post-arthrogram (shoulder, wrist)", "Upper extremity CTA" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Reverse-Barton-Fraktur_53W_-_CT_-_001.jpg/960px-Reverse-Barton-Fraktur_53W_-_CT_-_001.jpg", "caption": "Wrist CT with a sagittal reformation (left) and 3D volume-rendered views showing a reverse (volar) Barton fracture of the distal radius.", "credit": "Hellerhoff", "license": "CC BY-SA 4.0", "page_url": "https://commons.wikimedia.org/wiki/File:Reverse-Barton-Fraktur_53W_-_CT_-_001.jpg" }, "questions": [ { "q": "The shaded 3D wrist images shown were most likely created using which postprocessing technique?", "options": [ "Volume rendering", "Minimum intensity projection", "Curved planar reformation", "Filtered backprojection" ], "answer_index": 0, "explanation": "Volume rendering assigns opacity and shading to the full dataset to produce realistic 3D views of bone, useful for surgical planning." }, { "q": "For a unilateral shoulder CT, a common positioning approach is to:", "options": [ "Raise both arms overhead", "Place both hands on the abdomen", "Keep the affected arm at the side and raise the opposite arm overhead", "Scan the patient prone with the affected arm overhead" ], "answer_index": 2, "explanation": "Raising the unaffected arm removes it from the scan plane, reducing streak artifact through the shoulder of interest." }, { "q": "CT arthrography should be performed soon after the intra-articular injection because:", "options": [ "The radiation dose increases with delay", "The contrast becomes radioactive", "Contrast is absorbed and diluted over time, reducing joint distension and detail", "Iodine crystallizes in the joint" ], "answer_index": 2, "explanation": "Prompt scanning keeps the joint distended with dense contrast, outlining cartilage and labral defects." } ] }, { "region": "lower_extremity", "label": "Lower Extremity / Hip", "common_exams": [ "Hip", "Knee (tibial plateau)", "Ankle and foot", "Post-arthrogram knee", "Lower extremity CTA runoff" ], "image": { "url": "https://upload.wikimedia.org/wikipedia/commons/6/64/LipohemarthrosisCT.png", "caption": "Axial knee CT showing a fat–fluid level in the joint (lipohemarthrosis) from a tibial plateau fracture.", "credit": "James Heilman, MD", "license": "CC BY-SA 4.0", "page_url": "https://commons.wikimedia.org/wiki/File:LipohemarthrosisCT.png" }, "questions": [ { "q": "The knee image shows a fat–fluid level (lipohemarthrosis). Why does the top layer appear darker than the fluid beneath it?", "options": [ "It is fat from bone marrow, which has negative CT numbers and floats on blood", "It is air from an open wound", "It is iodinated contrast", "It is a ring artifact" ], "answer_index": 0, "explanation": "Marrow fat (about −100 HU) released through an intra-articular fracture floats on denser blood (about +40 to +60 HU)." }, { "q": "When planning a lower extremity CTA runoff, a key risk of using a very fast table speed is:", "options": [ "Increasing the effective dose fourfold", "Creating a ring artifact", "Preventing bolus tracking from triggering", "Outrunning the contrast bolus so distal vessels are not yet opacified" ], "answer_index": 3, "explanation": "Modern scanners can travel faster than contrast flows to the feet, so table speed or delay is adjusted to stay behind the bolus." }, { "q": "For tibial plateau fracture surgical planning, which reconstructions are most helpful?", "options": [ "Thick axial soft-tissue slices only", "Thin-slice sagittal and coronal MPRs with 3D rendering", "MinIP images", "Lung-kernel axial images" ], "answer_index": 1, "explanation": "Thin MPRs in two planes and 3D views show articular depression and fragment displacement." } ] } ] }