{ "modality": "Radiography", "spec_basis": "ARRT Radiography Examination Content Specifications effective January 1, 2022 (board approved January 2021), in effect for exams taken through February 28, 2027. A revised version takes effect March 1, 2027 (Patient Care 31, Safety 46, Image Production 51, Procedures 72; still 200 scored + 30 pilot questions).", "how_to_use": "Study in order of question weight: Procedures (66 questions, 33%) first, especially extremities, then Image Production (51) and Safety (50), then Patient Care (33). Learn each topic's must-know facts and board traps, drill the key numbers, and finish with the last-minute review the day before the exam.", "chapters": [ { "id": "patient-care", "category": "Patient Care", "scored_questions": 33, "weight_pct": 16.5, "topics": [ { "subcategory": "Patient Interactions and Management", "title": "Ethics, patient rights and consent", "must_know": [ "Informed consent requires a competent adult who is told the risks, benefits and alternatives; it can be withdrawn at any time, even mid-procedure.", "Implied consent covers unconscious or emergency patients; oral consent is valid for routine exams; minors need a parent or legal guardian unless emancipated.", "Consent must be obtained before any sedation or premedication that could impair judgment.", "HIPAA protects all protected health information (PHI); share only what is needed for care, and never discuss patients in public areas.", "The AHA Patient Care Partnership covers privacy, extent of care (e.g., DNR orders), access to information, advance directives and the right to refuse research.", "A living will states the patient's wishes for end-of-life care; a health care proxy (durable power of attorney for health care) names who decides when the patient cannot.", "ARRT Standards of Ethics: the Code of Ethics is aspirational guidance; the Rules of Ethics are mandatory and enforceable, and violations can lead to sanctions." ], "memory_tip": "Code = could (aspirational); Rules = required (enforceable).", "board_traps": [ "Family members cannot give informed consent for a competent adult patient.", "A signature alone is not informed consent if the patient was not told the risks and alternatives." ], "key_numbers": [] }, { "subcategory": "Patient Interactions and Management", "title": "Legal terms, doctrines and documentation", "must_know": [ "Battery is touching or treating without consent (including imaging a patient who refused); assault is the threat or fear of being touched.", "False imprisonment is unjustified restraint or confinement; restraints need a physician order, while sponges, sandbags and tape used as positioning aids do not.", "Negligence is failure to use reasonable care; malpractice is negligence by a professional; libel is written defamation and slander is spoken.", "Respondeat superior ('let the master answer') makes the employer liable for an employee's acts on the job; res ipsa loquitur ('the thing speaks for itself') shifts the burden of proof to the defendant.", "Ethical principles: beneficence (do good), nonmaleficence (do no harm), autonomy (patient's right to decide), justice (fairness), veracity (truthfulness).", "Verify identity with at least two identifiers and compare the order to the clinical indication; any order change requires a provider's order and documentation.", "Electronic manipulation must not misrepresent the exam: do not use electronic cropping or masking to hide anatomy that was exposed, and do not alter exposure indicator data." ], "memory_tip": null, "board_traps": [ "Positioning sponges and sandbags are not restraints; a restraint is anything that restricts movement against the patient's will.", "Masking off unwanted exposed anatomy after the fact does not replace proper collimation and can be a legal and ethical problem." ], "key_numbers": [] }, { "subcategory": "Patient Interactions and Management", "title": "Communication and patient education", "must_know": [ "Use a qualified medical interpreter for language barriers, not family members, especially not children.", "Nonverbal cues (eye contact, touch, facial expression, posture) often carry more meaning than words; touch must be appropriate and explained.", "Speak to the patient at their level: plain words for medical terms, simple explanations for children, and extra time and clear speech for geriatric or hearing-impaired patients.", "Kubler-Ross stages of grief: denial, anger, bargaining, depression, acceptance; patients may move through them in any order.", "Explain the exam's purpose, length, what the patient will feel and do, and radiation dose in understandable terms; confirm understanding with teach-back.", "Give clear pre-exam preps (e.g., NPO for upper GI, bowel cleansing for barium enema) and post-exam instructions (fluids and laxatives after barium to prevent impaction).", "Other modalities: MRI and ultrasound use no ionizing radiation; CT generally gives a higher dose than radiography; in nuclear medicine the patient is the radiation source." ], "memory_tip": "Grief stages: DABDA (Denial, Anger, Bargaining, Depression, Acceptance).", "board_traps": [ "Telling a patient 'this won't hurt' when it may is a veracity problem; explain honestly what they will feel." ], "key_numbers": [] }, { "subcategory": "Patient Interactions and Management", "title": "Body mechanics, transfers and medical equipment", "must_know": [ "Body mechanics: wide base of support, keep the load close to your body, bend at the knees not the waist, avoid twisting, and push rather than pull.", "Wheelchair and stretcher transfers: lock the wheels, move the patient toward their stronger side, and use a slider board, gait belt or mechanical (Hoyer) lift as needed.", "Keep IV bags about 18-24 in above the vein; never adjust an infusion pump rate or stop an infusion without an order.", "Oxygen is a drug: nasal cannula is low flow (about 1-6 L/min); a nonrebreather mask delivers high concentrations at about 10-15 L/min; never change the flow without an order.", "Keep urinary drainage bags and chest-tube drainage units below the level of the bladder or chest to prevent backflow; never lay them on the patient.", "Nasogastric tubes (e.g., Levin, Salem sump) are placed for feeding or decompression; do not clamp or disconnect suction without an order.", "Tracheostomy patients may need suctioning and cannot speak normally; keep the airway clear and offer another way to communicate." ], "memory_tip": null, "board_traps": [ "Raising the IV bag too high or lowering a drainage bag above the bladder causes problems: backflow for drainage, infiltration risk for IV." ], "key_numbers": [ { "label": "IV bag height", "value": "18-24 in above the vein" }, { "label": "Nasal cannula", "value": "about 1-6 L/min" }, { "label": "Nonrebreather mask", "value": "about 10-15 L/min" } ] }, { "subcategory": "Patient Interactions and Management", "title": "Vital signs, monitoring and falls", "must_know": [ "Adult pulse 60-100 beats/min: below 60 is bradycardia, above 100 is tachycardia; the radial pulse is most commonly used and the carotid is checked in adult CPR.", "Adult respirations 12-20 breaths/min; children and infants breathe and beat faster than adults.", "Blood pressure normal is below 120/80 mm Hg (AHA 2017 categories); hypertension stage 1 starts at 130 systolic or 80 diastolic; systolic below 90 suggests hypotension.", "Oral temperature about 37 C (98.6 F); rectal reads about 1 F higher and axillary about 1 F lower.", "Pulse oximetry (SpO2) is normally 95-100%; report readings below the patient's ordered threshold.", "Watch physical signs: level of consciousness, motor control, skin color and moisture (pale, cool, clammy suggests shock), and changes in severity of injury.", "Fall prevention: never leave a high-risk patient alone on the table, lock wheels, use side rails and assist with standing; most falls happen during transfers or when patients get up alone." ], "memory_tip": null, "board_traps": [ "Systolic is the top number (heart contracting); diastolic is the bottom number (heart relaxing)." ], "key_numbers": [ { "label": "Pulse", "value": "60-100 /min" }, { "label": "Respirations", "value": "12-20 /min" }, { "label": "Normal BP", "value": "<120/<80 mm Hg" }, { "label": "Temperature", "value": "37 C / 98.6 F" }, { "label": "SpO2", "value": "95-100%" } ] }, { "subcategory": "Patient Interactions and Management", "title": "Medical emergencies", "must_know": [ "Cardiac arrest: call for help, start CPR at 100-120 compressions/min, at least 2 in (5 cm) deep in adults, 30:2 compressions to breaths, and use an AED as soon as available.", "Latex allergy can cause anaphylaxis; use latex-free gloves, catheters, tourniquets and enema tips.", "Hypoglycemia (insulin reaction): shaky, sweaty, pale, confused; give sugar if the patient is conscious and can swallow.", "Hyperglycemia/diabetic ketoacidosis: thirst, frequent urination, fruity breath, deep rapid breathing; notify the physician.", "Seizure: protect the head and move objects away, do not restrain or put anything in the mouth, time it, then place the patient on their side.", "Syncope or vasovagal reaction: lay the patient supine and elevate the legs; shock signs are low blood pressure, rapid weak pulse, and cool clammy skin.", "Trauma: do not move a patient with suspected spinal injury until the cervical spine is cleared (horizontal-beam lateral first); stop bleeding with direct pressure.", "Stroke signs: facial droop, arm weakness, slurred speech; note the time of onset and call the rapid response team immediately." ], "memory_tip": "Stroke: FAST = Face, Arms, Speech, Time.", "board_traps": [ "Never put a bite block or fingers in a seizing patient's mouth." ], "key_numbers": [ { "label": "CPR rate", "value": "100-120 compressions/min" }, { "label": "Adult depth", "value": "at least 2 in (5 cm)" }, { "label": "Adult ratio", "value": "30:2" } ] }, { "subcategory": "Patient Interactions and Management", "title": "Infection control and hazardous materials", "must_know": [ "Chain of infection: pathogen, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host; hand hygiene is the best way to break it.", "Direct transmission is contact and droplet; indirect is airborne, vehicle (fomites like contaminated equipment), and vector (mechanical or biological, e.g., mosquitoes).", "Standard Precautions apply to every patient: hand hygiene, PPE for expected blood or body fluid contact, safe injection practices, and cleaning of equipment.", "Airborne precautions (N95 respirator, negative-pressure room): TB, measles, varicella; droplet (surgical mask within about 6 ft): influenza, pertussis, mumps; contact (gown and gloves): MRSA, VRE, C. difficile.", "Use soap and water, not alcohol rub, for C. difficile or visibly soiled hands; alcohol does not kill spores.", "Disinfection kills most microbes on surfaces; sterilization (e.g., steam autoclave) kills all microbes including spores. Sterile field: only waist level and above is sterile, and never turn your back on it.", "Neutropenic (reverse) isolation protects an immunocompromised patient from you; healthcare-associated (nosocomial) infections are acquired in the facility.", "Never recap needles; drop them in a puncture-proof sharps container. Safety data sheets (SDS) list hazards and handling for every chemical; chemotherapy drugs and their waste need special PPE and disposal." ], "memory_tip": "PPE on: gown, mask, goggles, gloves. PPE off: gloves first, then goggles, gown, mask (gloves are dirtiest).", "board_traps": [ "Reverse isolation protects the patient, not the staff.", "A sterile item touched by anything nonsterile is contaminated; when in doubt, it is not sterile." ], "key_numbers": [] }, { "subcategory": "Patient Interactions and Management", "title": "Pharmacology and contrast media", "must_know": [ "Before contrast: take medication history (medication reconciliation), allergy history and renal labs; normal creatinine is about 0.6-1.2 mg/dL and BUN about 7-20 mg/dL (lab ranges vary).", "ACR: metformin need not be stopped if eGFR is 30 or higher with no acute kidney injury (with eGFR below 30 or AKI, hold it 48 hours and recheck renal function); a common premedication for a prior reaction is prednisone 50 mg at 13, 7 and 1 hour before plus diphenhydramine 50 mg 1 hour before.", "Positive contrast (barium, iodine) absorbs more x-rays; negative contrast (air, CO2) absorbs less. Nonionic, low-osmolality iodinated agents cause fewer reactions than ionic high-osmolality agents.", "Use water-soluble iodinated contrast instead of barium if bowel perforation is suspected or before surgery; barium leaking into the peritoneum is dangerous.", "Schedule exams so contrast does not obscure others: non-contrast studies and iodinated studies before barium, and barium enema before upper GI.", "Routes: oral, IV, rectal, intrathecal (myelography), intramuscular, subcutaneous, intradermal; for venipuncture, tourniquet 3-4 in above the site and needle bevel up; a larger gauge number means a smaller needle.", "Local effects: extravasation (stop the injection, elevate the limb, notify and document) and phlebitis (vein inflammation). ACR systemic reaction severity: mild (limited hives, itching, nausea), moderate (diffuse hives, bronchospasm, facial edema without breathing difficulty), severe (laryngeal edema, hypoxia, anaphylactic shock, arrhythmia, seizure).", "Emergency drugs: epinephrine (anaphylaxis, bronchospasm), diphenhydramine (hives), albuterol inhaler (bronchospasm), atropine (bradycardia/vasovagal), naloxone (opioid reversal), nitroglycerin (angina), glucose or glucagon (hypoglycemia)." ], "memory_tip": "Contrast dose math: convert pounds to kilograms by dividing by 2.2, then multiply by the ordered mL/kg (or mg/kg).", "board_traps": [ "Vasovagal reaction = hypotension with a slow pulse (atropine, raise legs); anaphylactic shock = hypotension with a fast pulse (epinephrine).", "Do not leave a patient alone after contrast injection; most serious reactions occur within the first 20 minutes.", "Ionic contrast is never given intrathecally." ], "key_numbers": [ { "label": "Prednisone premed", "value": "50 mg at 13, 7, 1 h before" }, { "label": "Metformin hold", "value": "eGFR <30 or AKI: hold 48 h" }, { "label": "lb to kg", "value": "divide by 2.2" } ] } ] }, { "id": "safety", "category": "Safety", "scored_questions": 50, "weight_pct": 25.0, "topics": [ { "subcategory": "Radiation Physics and Radiobiology", "title": "X-ray production and the tube", "must_know": [ "Electrons are boiled off the heated tungsten filament (thermionic emission), focused by the negatively charged focusing cup, accelerated by kVp, and stopped at the anode target.", "Over 99% of the electrons' energy becomes heat; under 1% becomes x-rays.", "Bremsstrahlung (braking) radiation makes most of the diagnostic beam and gives a continuous spectrum; the maximum photon energy in keV equals the kVp.", "Characteristic radiation occurs when an incident electron ejects an inner-shell electron; tungsten K-shell binding energy is 69.5 keV, so useful K-characteristic x-rays need about 70 kVp or more.", "Tungsten is used for the target and filament because of its high atomic number (Z = 74) and high melting point (3,410 C).", "X-rays travel in straight lines at the speed of light, are electrically neutral, are polyenergetic, cannot be focused by a lens, ionize matter, cause some materials to fluoresce, and cause biologic damage." ], "memory_tip": "Brems = brakes (continuous spectrum); characteristic = specific shell energies (discrete lines).", "board_traps": [ "The maximum beam energy is set by kVp, not mA." ], "key_numbers": [ { "label": "Tungsten Z", "value": "74" }, { "label": "Tungsten K-shell binding energy", "value": "69.5 keV" }, { "label": "Energy to heat", "value": ">99%" } ] }, { "subcategory": "Radiation Physics and Radiobiology", "title": "Beam quality, quantity and the inverse square law", "must_know": [ "Beam quality (penetrability) is controlled mainly by kVp and filtration and is measured by half-value layer (HVL).", "Beam quantity (number of photons) is directly proportional to mAs and increases with roughly the square of kVp.", "Photon energy and frequency are directly related; wavelength is inversely related to both (higher kVp means shorter wavelength).", "Inverse square law: intensity varies inversely with the square of distance, I1/I2 = (D2/D1)^2; doubling distance cuts intensity to one quarter.", "Exposure maintenance (direct square) formula: mAs2/mAs1 = (D2/D1)^2; doubling SID requires four times the mAs.", "15% rule: a 15% increase in kVp roughly doubles receptor exposure, so +15% kVp with half the mAs keeps exposure about the same.", "Primary beam leaves the tube; remnant (exit) radiation leaves the patient and forms the image." ], "memory_tip": null, "board_traps": [ "Inverse square law (intensity drops as distance rises) and the exposure maintenance formula (mAs rises as distance rises) move in opposite directions." ], "key_numbers": [ { "label": "Double the distance", "value": "1/4 the intensity" }, { "label": "15% rule", "value": "+15% kVp ~ 2x exposure" } ] }, { "subcategory": "Radiation Physics and Radiobiology", "title": "Photon interactions and attenuation", "must_know": [ "Photoelectric absorption: a photon ejects an inner-shell electron and is totally absorbed; it creates image contrast and most patient dose.", "Photoelectric probability rises sharply with atomic number (about Z^3) and falls with photon energy (about 1/E^3), so it dominates at low kVp.", "Compton scatter: a photon ejects an outer-shell electron and continues in a new direction with less energy; it causes image fog and most occupational exposure.", "Compton scatter is essentially independent of atomic number and is the main interaction at higher diagnostic kVp.", "Coherent (classical) scatter occurs at very low energies (below about 10 keV), causes no ionization and only changes the photon's direction.", "Attenuation increases with part thickness, tissue density and atomic number: bone > muscle > fat > air; this differential absorption makes the image.", "Pair production (1.02 MeV and higher) does not occur in diagnostic radiography." ], "memory_tip": "Photoelectric = Patient dose and Picture contrast; Compton = Cloudy fog and Coworker exposure.", "board_traps": [ "Raising kVp increases the proportion of Compton scatter, but total patient dose usually drops because mAs can be lowered." ], "key_numbers": [] }, { "subcategory": "Radiation Physics and Radiobiology", "title": "SI units", "must_know": [ "SI units are the primary units on the radiography exam.", "Exposure is measured in coulombs per kilogram (C/kg) of air; 1 R = 2.58 x 10^-4 C/kg.", "Air kerma (Gy) is the kinetic energy released per unit mass of air and has largely replaced exposure on modern equipment.", "Absorbed dose is in gray (Gy); 1 Gy = 1 J/kg = 100 rad.", "Equivalent dose (Sv) = absorbed dose x radiation weighting factor; x-rays, gamma and beta have a weighting factor of 1, alpha particles 20.", "Effective dose (Sv) adds tissue weighting factors to estimate whole-body stochastic risk; it is used for dose limits. 1 Sv = 100 rem." ], "memory_tip": "Gy = what the tissue absorbed; Sv = what it means biologically.", "board_traps": [ "For diagnostic x-rays, 1 Gy absorbed dose = 1 Sv equivalent dose because the radiation weighting factor is 1." ], "key_numbers": [ { "label": "1 Gy", "value": "100 rad" }, { "label": "1 Sv", "value": "100 rem" }, { "label": "1 R", "value": "2.58 x 10^-4 C/kg" }, { "label": "W_R x-ray", "value": "1" }, { "label": "W_R alpha", "value": "20" } ] }, { "subcategory": "Radiation Physics and Radiobiology", "title": "Radiosensitivity and cell effects", "must_know": [ "Law of Bergonie and Tribondeau: cells are most radiosensitive when immature, undifferentiated, rapidly dividing and highly metabolic.", "Lymphocytes are the most radiosensitive blood cells; spermatogonia, erythroblasts and intestinal crypt cells are also highly sensitive; nerve and muscle cells are the least.", "Diagnostic x-rays are low-LET radiation (about 3 keV/um); higher LET means higher relative biologic effectiveness (RBE).", "Oxygen effect: well-oxygenated tissue is more radiosensitive; the oxygen enhancement ratio for x-rays is about 3.", "Most damage from x-rays is indirect: radiolysis of water forms free radicals that damage DNA, the target (master) molecule.", "Cells are most sensitive in mitosis (M phase) and least in late S phase.", "LD 50/30 for humans is about 3-4 Gy whole-body: the dose that would kill half the exposed population within 30 days without treatment.", "Linear non-threshold dose-response is used for stochastic effects and radiation protection; non-linear threshold curves describe deterministic effects." ], "memory_tip": null, "board_traps": [ "Mature red blood cells are not the most sensitive blood cells; lymphocytes are." ], "key_numbers": [] }, { "subcategory": "Radiation Physics and Radiobiology", "title": "Somatic, fetal and acute effects", "must_know": [ "Deterministic effects (tissue reactions) have a threshold and severity rises with dose: skin erythema (about 2 Gy), temporary epilation (about 3 Gy), cataracts, sterility.", "Stochastic effects have no threshold and probability rises with dose, but severity does not: cancer and genetic effects.", "ICRP now sets the lens cataract threshold at about 0.5 Gy.", "Radiation-induced cancers include leukemia (shortest latency), thyroid, breast, lung, bone and skin cancer.", "Embryo and fetus: highest risk in the first trimester; 0-2 weeks is all-or-nothing (loss or no effect); organogenesis (about weeks 2-8) carries the highest risk of malformations.", "ACOG: fetal doses below 50 mGy have not been linked to fetal anomalies or pregnancy loss; diagnostic radiographs deliver far less.", "Acute radiation syndromes: hematopoietic (about 2-10 Gy), gastrointestinal (about 10-50 Gy), central nervous system (above about 50 Gy); stages are prodromal, latent, manifest illness, then recovery or death." ], "memory_tip": "ARS order of dose: Blood, Gut, Brain (H-GI-CNS).", "board_traps": [ "Early effects appear within days to weeks after high doses; late effects (cancer, cataracts) appear months to years later." ], "key_numbers": [ { "label": "Lens threshold (ICRP)", "value": "~0.5 Gy" }, { "label": "Fetal no-effect level (ACOG)", "value": "<50 mGy" } ] }, { "subcategory": "Radiation Protection", "title": "Minimizing patient exposure", "must_know": [ "Use the highest practical kVp with the lowest mAs to lower patient dose while keeping image quality.", "Collimate to the area of interest; never open the field larger than the image receptor. Tight collimation lowers dose and scatter.", "Light field to x-ray field alignment must be within 2% of SID.", "Clear instructions, immobilization and short exposure times prevent repeats, which are a major source of unnecessary dose.", "Use PA instead of AP when possible to lower dose to breasts, thyroid and eyes (e.g., PA scoliosis series).", "Pediatric patients: use size-based techniques, immobilization and tight collimation (Image Gently). Large patients need higher kVp and may need multiple receptors rather than an open field.", "AAPM (2019) and NCRP (Statement 13, 2021) recommend against routine gonadal and fetal shielding in diagnostic radiography; follow facility policy.", "Record dose information: fluoroscopy time, cumulative air kerma and dose area product (DAP); DAP meters on the collimator measure dose x field area." ], "memory_tip": null, "board_traps": [ "Electronic cropping after the exposure does not reduce dose; only collimation before the exposure does.", "Digital receptors hide overexposure (the image still looks good), so watch exposure indicators to prevent dose creep." ], "key_numbers": [] }, { "subcategory": "Radiation Protection", "title": "Filtration, receptors and grids", "must_know": [ "Filtration removes low-energy photons that would only add skin dose; it raises average beam energy (hardens the beam) and raises HVL.", "NCRP #102 total filtration minimums: 2.5 mm Al equivalent above 70 kVp, 1.5 mm Al for 50-70 kVp, 0.5 mm Al below 50 kVp.", "Inherent filtration (glass or metal envelope, oil, window) is about 0.5 mm Al; added filtration (aluminum sheets) and the collimator mirror make up the rest.", "Compensating filters even out density across uneven parts: wedge (foot, thoracic spine), trough (chest), boomerang (shoulder).", "Receptors with higher detective quantum efficiency (DQE) need less radiation for the same image.", "Grids improve contrast but increase patient dose; use a grid when the part is more than 10 cm thick or above about 60 kVp." ], "memory_tip": null, "board_traps": [ "Filtration reduces patient skin dose but does not improve contrast; it slightly lowers contrast by hardening the beam." ], "key_numbers": [ { "label": ">70 kVp", "value": "2.5 mm Al total" }, { "label": "50-70 kVp", "value": "1.5 mm Al" }, { "label": "<50 kVp", "value": "0.5 mm Al" } ] }, { "subcategory": "Radiation Protection", "title": "Fluoroscopy dose reduction", "must_know": [ "Pulsed fluoroscopy at lower frame rates and last image hold reduce beam-on time and dose.", "Keep the image intensifier or flat panel as close to the patient as possible and the tube as far away as practical.", "Magnification mode increases patient dose because ABC raises the mA to keep brightness; use it only when needed.", "21 CFR limits: tabletop air kerma rate of 88 mGy/min (10 R/min) for normal mode and 176 mGy/min (20 R/min) for high-level control, which requires continuous manual activation and an audible signal.", "Minimum source-to-skin distance: 38 cm (15 in) for stationary fluoroscopes and 30 cm (12 in) for mobile C-arms.", "A cumulative timer sounds at 5 minutes of fluoroscopy time; fluoroscopes made after June 10, 2006 must display air kerma rate and cumulative air kerma.", "Removing the grid for small patients (e.g., pediatrics) lowers fluoroscopic dose." ], "memory_tip": null, "board_traps": [ "The 5-minute timer alerts the operator; it does not shut off the unit's ability to continue." ], "key_numbers": [ { "label": "Normal max", "value": "88 mGy/min (10 R/min)" }, { "label": "High-level max", "value": "176 mGy/min (20 R/min)" }, { "label": "SSD fixed", "value": ">=38 cm" }, { "label": "SSD mobile", "value": ">=30 cm" }, { "label": "Fluoro timer", "value": "5 min" } ] }, { "subcategory": "Radiation Protection", "title": "Personnel protection: time, distance, shielding", "must_know": [ "ALARA applies to personnel: keep time short, distance great, and shielding in place; distance is the most effective method.", "The patient is the main source of occupational exposure (scatter); at 1 m from the patient at 90 degrees, scatter is about 0.1% of the primary beam intensity.", "Leakage radiation from the tube housing may not exceed 100 mR/hr (about 0.88 mGy air kerma/hr) at 1 m with the tube at maximum ratings.", "Primary barriers are 1/16 in (1.6 mm) lead and extend 7 ft (2.1 m) high; secondary barriers are 1/32 in (0.8 mm) lead and overlap the primary barrier by 1/2 in.", "Never stand in the primary beam; never hold patients routinely. If someone must hold, use a non-pregnant family member with apron and gloves, not a radiographer.", "Mobile radiography: stand at least 2 m (6 ft) from the patient at a right angle to the scatter, using an exposure cord of that length, and wear an apron.", "Fluoroscopy: protective curtain and Bucky slot cover (at least 0.25 mm Pb equivalent each); with a C-arm, stand on the image receptor side, away from the tube." ], "memory_tip": "Tube side is the hot side.", "board_traps": [ "Lead aprons do not protect against the primary beam; step out of it." ], "key_numbers": [ { "label": "Primary barrier", "value": "1/16 in Pb, 7 ft high" }, { "label": "Secondary barrier", "value": "1/32 in Pb" }, { "label": "Leakage limit", "value": "100 mR/hr at 1 m" }, { "label": "Mobile distance", "value": ">=2 m (6 ft)" } ] }, { "subcategory": "Radiation Protection", "title": "Protective devices", "must_know": [ "NCRP #102 sets a minimum of 0.25 mm Pb equivalent for protective aprons, drapes and the Bucky slot cover; 0.5 mm Pb aprons are common in fluoroscopy.", "Lead gloves are at least 0.25 mm Pb equivalent; thyroid shields and leaded glasses protect the thyroid and lens.", "Attenuation by lead falls as kVp rises; a 0.5 mm Pb apron blocks most of the scatter at typical fluoroscopic energies.", "Hang aprons on racks; folding them cracks the lead, and cracked aprons fail inspection.", "Inspect aprons and gloves at least yearly (visually and by radiograph or fluoroscopy) and document results." ], "memory_tip": null, "board_traps": [ "A thicker apron protects more but is heavier; protection depends on lead equivalence, not apron weight alone." ], "key_numbers": [] }, { "subcategory": "Radiation Protection", "title": "Dose limits and monitoring (NCRP #116)", "must_know": [ "Occupational effective dose limit: 50 mSv per year; cumulative limit: 10 mSv x age in years.", "Annual equivalent dose limits: lens of the eye 150 mSv (NCRP #116; ICRP and NCRP commentary now recommend 50 mSv/yr), skin, hands and feet 500 mSv.", "Public limits: 1 mSv/yr for frequent exposure and 5 mSv/yr for infrequent exposure; students under 18 in training: 1 mSv/yr.", "Embryo/fetus of a declared pregnant worker: 0.5 mSv per month equivalent dose; declaration is voluntary and in writing.", "Monitoring is required when a worker could receive more than 10% of the annual limit; a pregnant worker wears a second dosimeter at waist level under the apron.", "Wear the main dosimeter at collar level outside the apron during fluoroscopy; never wear it during your own medical exams or leave it in the room.", "OSL dosimeters (aluminum oxide, read by laser, can be reread, sensitive to about 10 uSv) are most common; TLDs use lithium fluoride heated to release light; pocket ion chambers give immediate readings.", "Facilities keep personnel dosimetry records as regulations require, give workers their reports, and review readings against ALARA investigation levels; radioactive materials are labeled, stored and handled under the radiation safety officer's rules." ], "memory_tip": null, "board_traps": [ "Dose limits do not include medical or natural background exposure.", "The fetal limit is monthly once pregnancy is declared; the dosimeter goes under the apron at the waist." ], "key_numbers": [ { "label": "Occupational", "value": "50 mSv/yr" }, { "label": "Cumulative", "value": "10 mSv x age" }, { "label": "Lens (NCRP 116)", "value": "150 mSv/yr" }, { "label": "Skin/extremities", "value": "500 mSv/yr" }, { "label": "Public", "value": "1 mSv/yr (5 infrequent)" }, { "label": "Embryo/fetus", "value": "0.5 mSv/month" }, { "label": "Under-18 trainee", "value": "1 mSv/yr" }, { "label": "US average total (NCRP 160)", "value": "about 6.2 mSv/yr" } ] } ] }, { "id": "image-production", "category": "Image Production", "scored_questions": 51, "weight_pct": 25.5, "topics": [ { "subcategory": "Image Acquisition and Evaluation", "title": "Receptor exposure factors", "must_know": [ "Receptor exposure is directly proportional to mAs; mAs = mA x exposure time.", "kVp increases receptor exposure (15% rule) and changes beam penetration and subject contrast.", "Increasing SID lowers receptor exposure (inverse square law); compensate with the exposure maintenance formula.", "Grids, added filtration and tighter collimation all lower receptor exposure and need more mAs to compensate.", "Anode heel effect: beam intensity is greater on the cathode side; put the thicker part under the cathode (e.g., the hip end of the femur, the lower end of an AP thoracic spine).", "Heel effect is stronger with a shorter SID, a larger receptor and a smaller anode angle.", "Additive pathology needs more technique (ascites, pleural effusion, pneumonia, CHF/edema, Paget disease, osteoblastic metastases, hydrocephalus); destructive pathology needs less (emphysema, pneumothorax, osteoporosis, osteolytic metastases, bowel obstruction)." ], "memory_tip": "Cathode = fat end (thicker part under the cathode).", "board_traps": [ "Collimating tighter reduces scatter reaching the receptor, so receptor exposure falls even though mAs did not change." ], "key_numbers": [ { "label": "Grid conversion factors", "value": "none 1, 5:1 2, 6:1 3, 8:1 4, 12:1 5, 16:1 6" } ] }, { "subcategory": "Image Acquisition and Evaluation", "title": "Spatial resolution and distortion", "must_know": [ "Spatial resolution improves with a smaller focal spot, shorter OID, longer SID and no motion; motion is the greatest cause of unsharpness.", "Geometric unsharpness (penumbra) = focal spot size x OID / SOD.", "Magnification factor MF = SID / SOD; actual object size = image size / MF.", "Size distortion (magnification) is caused by OID and SID; shape distortion (elongation or foreshortening) by misalignment of tube, part or receptor.", "Angling the tube or receptor elongates the part; angling the part foreshortens it.", "Reduce motion with short exposure time, immobilization and clear breathing instructions; voluntary motion is controlled by communication, involuntary motion (peristalsis, heartbeat) only by short exposure time.", "Patient factors (thickness, pathology, ability to hold still) affect resolution and distortion as well as exposure." ], "memory_tip": "Elongation from the tube or IR; foreshortening from the part (Foreshortening = object Flexed/tilted).", "board_traps": [ "Focal spot size affects spatial resolution, not receptor exposure.", "Increasing OID magnifies the image and blurs it." ], "key_numbers": [ { "label": "Magnification factor", "value": "SID / SOD" }, { "label": "Unsharpness", "value": "FSS x OID / SOD" } ] }, { "subcategory": "Image Acquisition and Evaluation", "title": "Contrast, scatter and grids", "must_know": [ "kVp is the main controller of subject contrast: low kVp gives high (short-scale) contrast, high kVp gives low (long-scale) contrast; in digital imaging, displayed contrast is set mainly by processing (LUT).", "Scatter adds fog and lowers contrast; reduce it by collimating, compressing the part, using a grid and using an appropriate kVp.", "Grid ratio = height of lead strips / distance between them; higher ratio cleans up more scatter but needs more mAs and has less positioning latitude.", "Grid cutoff: off-level and off-center cause loss of exposure across the whole image; off-focus causes loss at the edges; an upside-down focused grid causes severe loss at both edges with the center exposed.", "Air gap technique (increased OID) reduces scatter reaching the receptor without a grid, at the cost of magnification.", "Bit depth sets the number of gray shades available: 2^n (12-bit = 4,096; 14-bit = 16,384)." ], "memory_tip": null, "board_traps": [ "Off-level grid errors are the most common cutoff error with portable exams.", "In digital imaging, increasing kVp does not make the image look darker after processing; it changes noise, subject contrast and dose." ], "key_numbers": [ { "label": "12-bit", "value": "4,096 shades" }, { "label": "14-bit", "value": "16,384 shades" } ] }, { "subcategory": "Image Acquisition and Evaluation", "title": "Technique charts and special considerations", "must_know": [ "Fixed-kVp/variable-mAs charts use the optimal kVp for each part and change mAs with patient size; they give more consistent contrast.", "Variable-kVp charts keep mAs fixed and change kVp (about 2 kVp per cm of part thickness).", "Anatomically programmed technique (APR) preselects factors by exam; always check and adjust for the patient.", "Plaster casts need more technique than fiberglass casts; wet plaster needs more than dry. Fiberglass needs little or no increase.", "Pediatric patients need less technique; geriatric patients often need less because of bone loss; high-BMI patients need more kVp.", "Barium studies use high kVp (about 100-125 single contrast, about 90-100 double contrast); iodinated studies use about 70-80 kVp to match iodine's K-edge (33 keV).", "Increasing OID (air gap) or adding a grid changes the needed technique; reflect both on the chart." ], "memory_tip": null, "board_traps": [ "Using single-contrast barium kVp on an iodinated study washes out the iodine." ], "key_numbers": [] }, { "subcategory": "Image Acquisition and Evaluation", "title": "Automatic exposure control (AEC)", "must_know": [ "AEC ends the exposure when a set amount of radiation reaches the detectors; most systems use ionization chambers placed between the patient and the receptor.", "With AEC, kVp still controls penetration and contrast; changing mA changes exposure time, and the total mAs adjusts automatically.", "Select the detector(s) under the anatomy of interest: both outer cells for a PA chest, center cell for a lateral chest or lateral lumbar spine.", "Centering errors matter: a detector under a dense area (metal, contrast) lengthens the exposure; one under thin anatomy or open air ends it early (underexposure).", "Set the backup timer at about 150% of the expected exposure; federal rules cap AEC exposures at 600 mAs (or 60 kWs) above 50 kVp.", "Minimum response time (shortest possible exposure, about 1 ms) can overexpose very small parts or small children.", "Density controls (+1/-1, +2/-2) change the exposure by a fixed vendor-specific percentage." ], "memory_tip": null, "board_traps": [ "AEC cannot fix poor positioning; the anatomy must be over the selected chamber.", "Opening the collimator wide adds scatter that can end the AEC exposure early." ], "key_numbers": [ { "label": "Backup timer", "value": "~150% of expected" }, { "label": "Federal AEC cap", "value": "600 mAs above 50 kVp" }, { "label": "Min response time", "value": "~1 ms" } ] }, { "subcategory": "Image Acquisition and Evaluation", "title": "Digital image characteristics", "must_know": [ "Pixel size = field of view / matrix; a larger matrix or smaller FOV gives smaller pixels and better spatial resolution.", "Pixel pitch is the center-to-center distance between pixels; DEL pitch and fill factor (the percentage of each detector element that is sensitive) limit DR resolution.", "CR spatial resolution depends on sampling frequency (pixels per mm); the Nyquist frequency, the highest frequency recorded, is half the sampling frequency.", "MTF describes how faithfully a system reproduces detail (1 = perfect); DQE describes how efficiently it turns x-rays into signal.", "Dynamic range is the span of exposures the receptor can record; digital receptors have a wide range, giving wide exposure latitude.", "Quantum mottle (noise) comes from too few photons; fix it with more mAs. Higher SNR means a cleaner image.", "Gross overexposure saturates pixels (black, data lost and cannot be recovered); gross underexposure gives unacceptable noise." ], "memory_tip": null, "board_traps": [ "Image processing cannot fix quantum mottle or saturation; only repeating with correct technique can." ], "key_numbers": [] }, { "subcategory": "Image Acquisition and Evaluation", "title": "Exposure indicators, identification and evaluation", "must_know": [ "IEC 62494-1 exposure index (EI) is proportional to receptor exposure; deviation index DI = 10 log10(EI / target EI).", "DI 0 is the target; +1 is about 26% overexposed, +3 is double, -3 is half; AAPM TG-116 suggests action ranges, with -1 to +1 generally acceptable.", "Vendor indicators differ: Fuji/Konica S-value is inversely proportional to exposure; Carestream EI rises by 300 per doubling; Agfa lgM rises by 0.3 per doubling.", "Evaluate every image for exposure indicator, noise, contrast, spatial resolution, distortion, correct markers, anatomy included and artifacts.", "Each image needs patient name/ID, date, facility and a lead side marker placed in the collimated field during the exposure; an electronic annotation added afterward is not a substitute.", "CR artifacts include plate scratches, dust, grid moire (grid lines parallel to the scan lines), phantom images from incomplete erasure, and fog because PSP plates are sensitive to scatter and background radiation.", "DR artifacts include dead pixels or lines (need recalibration) and ghosting; histogram errors come from wrong exam selection, poor collimation recognition or off-center anatomy." ], "memory_tip": null, "board_traps": [ "A low S-value on a Fuji system means overexposure, not underexposure.", "An image with a good-looking brightness can still be overexposed; check the exposure indicator." ], "key_numbers": [ { "label": "DI +1", "value": "~26% over" }, { "label": "DI +3", "value": "2x exposure" }, { "label": "DI -3", "value": "1/2 exposure" } ] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "Generator, transformers and rectification", "must_know": [ "Transformer law: Vs/Vp = Ns/Np; current changes inversely to voltage.", "The step-up (high-voltage) transformer makes kVp; the step-down (filament) transformer lowers voltage and raises current to heat the filament; the autotransformer (one winding, self-induction) selects kVp.", "Rectifiers (solid-state diodes) change AC to DC so electrons flow only cathode to anode.", "Voltage ripple: single-phase 100%, three-phase 6-pulse about 13%, three-phase 12-pulse about 4%, high-frequency under 1%; lower ripple means higher average energy and more output.", "Single-phase full-wave rectification gives 120 pulses per second on 60 Hz power.", "Heat units: single-phase HU = kVp x mA x s; multiply by 1.35 for three-phase 6-pulse and 1.41 for 12-pulse or high-frequency.", "Use tube rating charts (single-exposure limits) and anode and housing cooling charts to prevent overloading; warm up a cold tube to avoid cracking the anode." ], "memory_tip": null, "board_traps": [ "The filament transformer is a step-down transformer, not step-up." ], "key_numbers": [ { "label": "6-pulse ripple", "value": "~13%" }, { "label": "12-pulse ripple", "value": "~4%" }, { "label": "High frequency", "value": "<1%" }, { "label": "HU factor 3-phase 6-pulse", "value": "1.35" }, { "label": "HU factor 12-pulse/HF", "value": "1.41" } ] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "X-ray tube and console", "must_know": [ "Cathode: thoriated tungsten filaments (small and large focal spots) in a nickel focusing cup; space charge is the electron cloud around the filament.", "Anode: tungsten-rhenium target on a molybdenum disk, spun by an induction motor (stator outside the envelope, rotor inside) at about 3,400 rpm, or about 10,000 rpm for high-speed tubes.", "Line focus principle: a smaller anode angle makes a smaller effective focal spot but a stronger heel effect and smaller field coverage.", "Pressing the prep (rotor) button heats the filament and spins the anode; the second stage makes the exposure.", "Tungsten vaporizes and coats the inside of the envelope over time, which can cause arcing; long filament heating shortens tube life.", "Console controls set kVp, mA, time (or AEC) and focal spot; a line voltage compensator corrects incoming power fluctuations." ], "memory_tip": null, "board_traps": [ "Small focal spot = better detail but lower heat capacity, so it limits mA." ], "key_numbers": [] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "Image receptors: CR and DR", "must_know": [ "CR plates use a photostimulable phosphor (barium fluorohalide with europium) that stores the latent image in electron traps.", "The CR reader scans the plate with a red laser; the plate emits blue-violet light that a photomultiplier or photodiode turns into a signal, and bright white light erases the plate.", "Direct-conversion DR uses amorphous selenium (a-Se) to change x-rays directly into charge, read out by a thin-film transistor (TFT) array.", "Indirect-conversion DR uses a scintillator (cesium iodide or gadolinium oxysulfide) that makes light, which amorphous silicon photodiodes, CCDs or CMOS sensors then convert to charge.", "Cesium iodide's needle-like crystals channel light and limit spread, improving resolution.", "CCD systems need lenses or fiber optics to shrink the light image onto a small chip, which loses some light." ], "memory_tip": "Direct = selenium, straight to charge; Indirect = Scintillator first, then silicon.", "board_traps": [ "Amorphous selenium is direct conversion; amorphous silicon is part of indirect conversion." ], "key_numbers": [] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "Fluoroscopic equipment", "must_know": [ "Image intensifier: input phosphor (cesium iodide) makes light, photocathode releases electrons, electrostatic lenses focus them, anode accelerates them (about 25 kV) to the output phosphor (zinc cadmium sulfide).", "Brightness gain = minification gain x flux gain; minification gain = (input diameter / output diameter)^2.", "Magnification mode uses a smaller part of the input phosphor: better spatial resolution, smaller field, higher patient dose.", "Image intensifiers show vignetting (dim edges) and pincushion distortion; flat-panel detectors do not.", "Automatic brightness control (ABC/AERC) adjusts mA and/or kVp to keep image brightness constant as part thickness changes.", "Images are viewed on monitors and recorded as spot images, fluoro loops or last image hold; in conventional R/F rooms the tube is under the table, which lowers operator dose." ], "memory_tip": null, "board_traps": [ "Magnification mode increases, not decreases, patient dose." ], "key_numbers": [ { "label": "Minification gain", "value": "(input / output diameter)^2" } ] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "Beam restriction and accessories", "must_know": [ "Beam restrictors: aperture diaphragms, cones and cylinders, and variable-aperture collimators (most common).", "Positive beam limitation (PBL) automatically collimates to the receptor size.", "Stationary grids can show grid lines; the Bucky (moving or reciprocating) grid blurs the lead lines.", "Focused grids must be used within their focal range and with the tube centered; parallel grids cut off at short SIDs.", "Compensating filters (wedge, trough, boomerang) even out density across uneven parts." ], "memory_tip": null, "board_traps": [ "A stationary grid line pattern in CR can cause moire artifacts when grid lines run parallel to the reader scan direction." ], "key_numbers": [] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "Image processing, display and informatics", "must_know": [ "Pre-processing: the analog-to-digital converter (ADC) digitizes the signal and quantization assigns each pixel a value; corrections include rescaling, flat-fielding (uneven detector response) and dead pixel interpolation.", "The histogram (pixel values vs frequency) locates the values of interest (VOI); selecting the wrong body part or poor collimation causes histogram analysis errors.", "The look-up table (LUT) maps raw values to display values and sets the image's contrast.", "Edge enhancement sharpens edges but increases noise and can cause halo artifacts; smoothing reduces noise; equalization compresses dynamic range to show thick and thin areas together.", "Window level controls brightness and window width controls contrast: a narrow width gives higher contrast.", "Post-processing includes brightness, contrast, ROI, electronic cropping or masking (shuttering) and stitching for long images (scoliosis, long leg).", "Monitors: view straight on (off-angle viewing loses contrast) with low ambient light; DICOM Grayscale Standard Display Function (GSDF) keeps grayscale consistent.", "HIS (facility), RIS (radiology scheduling and reports), EMR/EHR (patient record); PACS stores and displays images; DICOM is the image format and communication standard; HL7 carries text data between systems. During downtime, follow manual procedures and reconcile later." ], "memory_tip": null, "board_traps": [ "Window width = contrast; window level = brightness.", "DICOM is for images; HL7 is for text and orders." ], "key_numbers": [] }, { "subcategory": "Equipment Operation and Quality Assurance", "title": "Quality control", "must_know": [ "Light field and x-ray field must align within 2% of SID; the central ray must align with the center of the light field.", "Exposure reproducibility within 5%, mA/mAs linearity within 10% between adjacent stations, timer accuracy within 5% for exposures over 10 ms.", "CR QC: erasure thoroughness, plate uniformity, spatial resolution, reader laser and calibration; erase plates that have sat unused, since they collect background fog.", "DR QC: detector calibration (flat-field/gain), dead pixel mapping, uniformity and spatial resolution testing.", "Display QC: luminance, uniformity and GSDF calibration using test patterns (e.g., AAPM TG-18).", "Inspect lead aprons, gloves and thyroid shields at least yearly; a common rejection guide is defects over 15 mm2 near critical organs, 670 mm2 elsewhere, or 11 mm2 on thyroid shields.", "Report malfunctions (unusual noises, repeated artifacts, error messages) to the supervisor or physicist, take the unit out of service if unsafe, and document." ], "memory_tip": null, "board_traps": [ "Fixing a malfunction yourself without authorization is not the right answer; stop, report, document." ], "key_numbers": [ { "label": "Collimation accuracy", "value": "+/-2% of SID" }, { "label": "Reproducibility", "value": "+/-5%" }, { "label": "Linearity", "value": "+/-10%" }, { "label": "Timer (>10 ms)", "value": "+/-5%" } ] } ] }, { "id": "procedures", "category": "Procedures", "scored_questions": 66, "weight_pct": 33.0, "topics": [ { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Positioning terms, lines and landmarks", "must_know": [ "Projection = path of the central ray (AP, PA); position = the patient's body position (supine, prone, decubitus, LPO); view = how the receptor sees the part, used only for the image.", "Decubitus always means lying down with a horizontal beam and is named for the side down (left lateral decubitus = left side down).", "Oblique names use the side closest to the receptor: LPO = left posterior side against the IR, RAO = right anterior side against the IR.", "Skull lines: OML (outer canthus to EAM), IOML (infraorbital margin to EAM), MML (mentum to EAM), AML (acanthion to EAM); OML and IOML differ by about 7 degrees.", "Landmarks: mastoid tip C1, gonion C3, thyroid cartilage C4-C5, vertebra prominens C7, jugular notch T2-T3, sternal angle T4-T5, xiphoid T9-T10.", "Lower landmarks: inferior costal margin L2-L3, iliac crest L4-L5, ASIS S1-S2, greater trochanter and pubic symphysis at the level of the coccyx." ], "memory_tip": "Decubitus = horizontal beam, named for the side DOWN.", "board_traps": [ "LPO and RAO are the same body rotation imaged from opposite directions (AP vs PA); they show similar anatomy but with different OID." ], "key_numbers": [ { "label": "OML vs IOML", "value": "7 degrees" }, { "label": "Iliac crest", "value": "L4-L5" }, { "label": "Jugular notch", "value": "T2-T3" }, { "label": "Xiphoid", "value": "T9-T10" } ] }, { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Skull", "must_know": [ "AP axial (Towne): CR 30 degrees caudal to OML (37 degrees to IOML); shows occipital bone with the dorsum sellae and posterior clinoids inside the foramen magnum.", "PA axial (Caldwell): CR 15 degrees caudal to OML; petrous ridges in the lower third of the orbits. PA with 0 degrees: petrous ridges fill the orbits.", "Lateral: midsagittal plane parallel and interpupillary line perpendicular to the IR; CR 2 in above the EAM; sella turcica in profile and orbital roofs superimposed.", "Submentovertex (full basal): IOML parallel to the IR, CR perpendicular to IOML; shows the skull base and foramina ovale and spinosum.", "Trauma: horizontal-beam (cross-table) lateral shows an air-fluid level in the sphenoid sinus, a sign of basal skull fracture.", "Trauma AP axial (reverse Caldwell) uses a 15 degree cephalic angle to OML; trauma AP axial (Towne) uses 30 degrees caudal to OML, with the patient supine and head not moved." ], "memory_tip": "Towne 30 caudal; Caldwell 15 caudal (fifteen = face).", "board_traps": [ "Rotation on a lateral skull shows as unequal mandibular rami and orbital roofs; tilt shows as unequal orbital roofs splitting vertically." ], "key_numbers": [ { "label": "Towne", "value": "30 caud to OML / 37 to IOML" }, { "label": "Caldwell", "value": "15 caud to OML" } ] }, { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Facial bones, nasal bones, orbits and sinuses", "must_know": [ "Parietoacanthial (Waters): OML 37 degrees to the IR, MML perpendicular; petrous ridges just below the maxillary sinuses; best single view of facial bones and maxillary sinuses.", "Modified Waters: OML 55 degrees to the IR; petrous ridges in the lower half of the maxillary sinuses; best for orbital floors (blowout fracture).", "Lateral facial bones: CR to the zygoma; lateral nasal bones: CR about 1/2 in distal to nasion with low technique.", "Waters is the standard view to screen the orbits for metal foreign bodies before MRI.", "Sinus images must be erect with a horizontal beam to show air-fluid levels; allow time for fluid to settle.", "Sinus projections: Caldwell for frontal and anterior ethmoid sinuses, Waters for maxillary, lateral for all four, SMV for sphenoid and ethmoid; lateral CR is 1/2-1 in posterior to the outer canthus." ], "memory_tip": null, "board_traps": [ "Supine sinus images cannot show air-fluid levels.", "Waters puts the OML at 37 degrees; modified Waters at 55 degrees." ], "key_numbers": [ { "label": "Waters", "value": "OML 37 deg to IR" }, { "label": "Modified Waters", "value": "OML 55 deg to IR" } ] }, { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Mandible and TMJs", "must_know": [ "Axiolateral oblique mandible: CR 25 degrees cephalic; head rotation shows different parts: true lateral for the ramus, 30 degrees toward the IR for the body, 45 degrees for the mentum.", "PA mandible shows rami and lateral body; PA axial uses about 20-25 degrees cephalic to show condyles.", "AP axial (Towne) mandible uses about 35 degrees caudal to OML to show condyles and TMJs.", "Modified Law TMJ (axiolateral oblique): head rotated 15 degrees toward the IR and CR 15 degrees caudal; modified Schuller: true lateral with CR 25-30 degrees caudal.", "TMJ studies are done with mouth open and closed for comparison; the side closest to the IR is the one shown.", "SMV of the mandible shows the coronoid and condyles of the whole mandible." ], "memory_tip": "Law = 15 and 15.", "board_traps": [ "Opening the mouth is not done when a fracture is suspected; ask before moving the jaw." ], "key_numbers": [] }, { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Cervical and thoracic spine", "must_know": [ "AP axial C-spine: CR 15-20 degrees cephalic to C4, shows C3-C7 and open intervertebral disk spaces.", "AP open mouth: line from the lower edge of the upper incisors to the mastoid tips perpendicular to the IR; shows C1-C2 and the dens. Fuchs (AP dens): chin raised until the MML is near perpendicular, dens inside the foramen magnum.", "Lateral C-spine: 72 in SID to reduce magnification, shoulders depressed, CR at C4; shows zygapophyseal joints and disk spaces; must include C7-T1.", "Obliques show intervertebral foramina: posterior oblique (AP axial, 15-20 cephalic) shows foramina farthest from the IR; anterior oblique (PA axial, 15-20 caudal) shows foramina closest to the IR.", "Cervicothoracic lateral (swimmer's) shows C7-T1 when shoulders obscure it; flexion and extension laterals show ligament instability.", "Trauma: horizontal-beam lateral first, collar left on, cleared by a physician before any other views or movement.", "Thoracic spine: AP with CR at T7, cathode toward the feet; lateral with breathing technique (long time, low mA) blurs ribs and lung markings; scoliosis series is done erect, preferably PA to lower breast and thyroid dose." ], "memory_tip": "C-spine obliques: Anterior = Adjacent (side closest); Posterior = farthest.", "board_traps": [ "Swimmer's and flexion/extension views are never done before trauma clearance.", "Forgetting C7 on a lateral C-spine makes the exam incomplete." ], "key_numbers": [ { "label": "Lateral C-spine SID", "value": "72 in" }, { "label": "Oblique C-spine", "value": "45 deg, 15-20 deg angle" } ] }, { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Lumbar spine, sacrum, coccyx, SI joints and myelography", "must_know": [ "AP L-spine: knees flexed to reduce lordosis and bring the back flat; CR at the iliac crest for a large receptor or at L3 (lower costal margin) for a smaller one; PA opens disk spaces with beam divergence.", "45 degree obliques show zygapophyseal joints ('Scottie dog'): posterior oblique shows the joints closest to the IR, anterior oblique those farthest.", "Scottie dog: eye = pedicle, nose = transverse process, ear = superior articular process, neck = pars interarticularis, front leg = inferior articular process, body = lamina. A broken 'collar' = spondylolysis.", "L5-S1: lateral spot CR about 1.5 in below the iliac crest and 2 in posterior to the ASIS; AP axial uses 30 degrees cephalic (men) or 35 degrees (women).", "Sacrum AP axial: 15 degrees cephalic; coccyx AP axial: 10 degrees caudal; empty the bladder first.", "SI joints: AP axial 30-35 degrees cephalic; 25-30 degree posterior obliques show the joint farthest from the IR, anterior obliques the joint closest.", "Myelography: nonionic water-soluble iodinated contrast injected intrathecally, usually at L2-L3 or L3-L4 (below the conus) or C1-C2; the head is kept extended during tilting so contrast does not flow into the brain." ], "memory_tip": null, "board_traps": [ "Lumbar oblique joint rules are the reverse of C-spine foramina rules.", "Ionic contrast must never be injected intrathecally." ], "key_numbers": [ { "label": "L5-S1 AP axial", "value": "30 male / 35 female cephalic" }, { "label": "Sacrum", "value": "15 cephalic" }, { "label": "Coccyx", "value": "10 caudal" }, { "label": "SI AP axial", "value": "30-35 cephalic" } ] }, { "subcategory": "Head, Spine and Pelvis Procedures", "title": "Pelvis and hip", "must_know": [ "AP pelvis: feet internally rotated 15-20 degrees to put femoral necks parallel to the IR; greater trochanters in profile, lesser trochanters barely visible.", "If a hip fracture is suspected (shortened, externally rotated leg), do not rotate the leg; image it as it lies.", "Frog-leg (bilateral or unilateral): thighs abducted about 40-45 degrees from vertical; contraindicated with suspected fracture.", "Cross-table (axiolateral inferosuperior, Danelius-Miller) lateral hip: unaffected leg raised, IR parallel and CR perpendicular to the femoral neck; the trauma lateral.", "Clements-Nakayama: trauma lateral when the opposite leg cannot be raised; leg stays neutral and the CR is angled about 15 degrees posteriorly and perpendicular to the femoral neck.", "Inlet view: about 40 degrees caudal; outlet view: about 20-35 degrees cephalic in men and 30-45 degrees in women.", "Judet views: 45 degree posterior obliques of the pelvis show the acetabular rims and columns; image both sides." ], "memory_tip": null, "board_traps": [ "Frog-leg is never the trauma lateral; cross-table (Danelius-Miller) is.", "Visible lesser trochanters on an AP hip mean the leg was not internally rotated." ], "key_numbers": [ { "label": "AP pelvis rotation", "value": "15-20 deg internal" }, { "label": "Inlet", "value": "40 caud" }, { "label": "Outlet", "value": "20-35 M / 30-45 F cephalic" } ] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Chest", "must_know": [ "PA and lateral erect at 72 in SID to reduce heart magnification and show air-fluid levels; full inspiration on the second breath shows at least 10 posterior ribs above the diaphragm.", "PA: shoulders rolled forward to move the scapulae off the lungs; CR at T7 (about 7-8 in below the vertebra prominens); no rotation when the sternoclavicular joints are equidistant from the spine.", "Lateral: left lateral routinely to bring the heart closer to the IR; arms raised; high kVp (about 110-125) for contrast across lungs and mediastinum.", "AP supine magnifies the heart and cannot show air-fluid levels; AP lordotic (or 15-20 degree cephalic angle) projects the clavicles above the apices.", "Lateral decubitus: for fluid, affected side down; for free air or pneumothorax, affected side up; wait about 5 minutes before exposing.", "Inspiration and expiration PAs help show a small pneumothorax.", "The right main bronchus is wider, shorter and more vertical, so aspirated objects usually go right; the carina is at about T4-T5 and an endotracheal tube tip sits about 3-5 cm above it." ], "memory_tip": "Decub: Fluid falls (side down), air rises (side up).", "board_traps": [ "On an AP chest the scapulae are usually over the lungs; that is expected, not a positioning error.", "A lateral chest with posterior ribs not superimposed is rotated." ], "key_numbers": [ { "label": "Chest SID", "value": "72 in" }, { "label": "Posterior ribs on inspiration", "value": ">=10" }, { "label": "Chest kVp", "value": "about 110-125" } ] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Ribs, sternum, SC joints and soft tissue neck", "must_know": [ "Ribs above the diaphragm: inspiration, erect if possible; below the diaphragm: expiration, recumbent; mark the injury site.", "Rib obliques: posterior injury uses a posterior oblique with the affected side toward the IR; anterior injury uses an anterior oblique with the affected side away from the IR.", "Sternum: RAO about 15-20 degrees so the heart shadow is behind the sternum; thin patients need more rotation, large chests less; breathing technique blurs lung markings.", "Lateral sternum: shoulders pulled back, 72 in SID to reduce magnification.", "SC joints: PA bilateral and 10-15 degree anterior obliques; the oblique shows the joint closest to the IR.", "Soft tissue neck: AP and lateral upper airway, lateral taken during slow inspiration; croup shows a 'steeple sign' on the AP, epiglottitis a 'thumb sign' on the lateral." ], "memory_tip": null, "board_traps": [ "The sternum is obliqued RAO, not LAO, to use the heart as a uniform background." ], "key_numbers": [ { "label": "Sternum", "value": "RAO 15-20 deg" }, { "label": "SC obliques", "value": "10-15 deg" } ] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Abdomen and body habitus", "must_know": [ "AP supine (KUB): CR at the iliac crest, exposed on expiration; include from the kidneys to the pubic symphysis.", "AP upright: CR about 2 in above the iliac crest to include the diaphragms; shows free air under the diaphragm and air-fluid levels.", "Left lateral decubitus (left side down): free air rises over the liver on the right where it is easiest to see; keep the patient on the side about 5 minutes before exposing.", "Dorsal decubitus (supine, horizontal-beam lateral) shows free air, aortic calcification and masses anterior to the spine.", "Acute abdomen series: PA erect chest (best for free air under the diaphragm), upright abdomen and supine abdomen.", "Body habitus: sthenic about 50%, hyposthenic 35%, asthenic 10% (low, vertical stomach and gallbladder), hypersthenic 5% (high, transverse stomach and gallbladder).", "A good abdomen image shows psoas muscle borders, kidney outlines, lower liver margin and transverse processes." ], "memory_tip": "Hypersthenic = High and transverse; Asthenic = low and vertical.", "board_traps": [ "Right side down is wrong for free air: the gastric bubble on the left can mimic free air." ], "key_numbers": [ { "label": "Sthenic", "value": "50%" }, { "label": "Hyposthenic", "value": "35%" }, { "label": "Asthenic", "value": "10%" }, { "label": "Hypersthenic", "value": "5%" } ] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Esophagus and swallowing study", "must_know": [ "Esophagram: RAO 35-40 degrees places the esophagus between the heart and spine; also left lateral, AP/PA and LAO.", "Thick barium is used to coat the esophagus; the patient takes it during the exposure or fluoroscopy.", "Esophageal findings: varices, hiatal hernia, Zenker diverticulum, achalasia ('bird's beak'), strictures and reflux.", "Swallowing dysfunction study (modified barium swallow) is done with a speech-language pathologist, mainly in the lateral position, with liquids and foods of different thicknesses to look for penetration and aspiration." ], "memory_tip": null, "board_traps": [ "The esophagus is obliqued RAO, not LPO, to clear it from the spine." ], "key_numbers": [ { "label": "Esophagram oblique", "value": "RAO 35-40 deg" } ] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Upper GI and small bowel", "must_know": [ "Prep: NPO for about 8 hours (usually after midnight); double contrast uses gas crystals plus high-density barium.", "Barium goes to the dependent part: RAO and right lateral fill the pylorus, duodenal bulb and C-loop with barium.", "LPO and AP put air in the pylorus and duodenal bulb (double contrast) and barium in the fundus; AP Trendelenburg can show a hiatal hernia.", "PA shows the body and pylorus; in hypersthenic patients the stomach is high and transverse, in asthenic patients low and vertical. Sthenic CR about L1-L2.", "Right lateral shows the retrogastric space, pylorus and duodenum.", "Small bowel series: prone PA images (compression separates loops), timed every 15-30 minutes until barium reaches the ileocecal valve, then compression spot images of the terminal ileum.", "The duodenojejunal flexure is held by the ligament of Treitz." ], "memory_tip": "RAO = Right side down: barium Rolls into the duodenum; LPO = air in the duodenum.", "board_traps": [ "LPO is a posterior oblique: the left side is down and the fundus fills with barium.", "Supine images put air in the anterior structures; prone images put barium there." ], "key_numbers": [] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Contrast enema", "must_know": [ "Contraindicated with suspected perforation or toxic megacolon (use water-soluble contrast if perforation is a concern).", "Insert the enema tip in the Sims position (left side down, right knee flexed); aim toward the umbilicus 1-1.5 in, then superiorly; bag no more than 24 in above the table.", "Posterior obliques open the flexure on the side up: LPO shows the right colic (hepatic) flexure, RPO the left colic (splenic) flexure.", "Anterior obliques open the flexure on the side down: RAO hepatic, LAO splenic.", "Double contrast decubitus: the side up fills with air; left lateral decubitus shows the lateral ascending and medial descending colon, right lateral decubitus the opposite.", "Sigmoid: AP axial 30-40 degrees cephalic or PA axial 30-40 degrees caudal; lateral rectum; post-evacuation image after the patient empties.", "Findings: diverticulosis, polyps, 'apple-core' lesion (carcinoma), intussusception, volvulus." ], "memory_tip": "Posterior oblique = flexure Up opens; Anterior oblique = flexure down opens (RAO/LPO hepatic; LAO/RPO splenic).", "board_traps": [ "Inserting the tip straight up and back first can injure the rectum; follow the anorectal angle: anterior toward the umbilicus, then superior." ], "key_numbers": [ { "label": "Bag height", "value": "<=24 in above table" }, { "label": "Tip insertion", "value": "1-1.5 in" }, { "label": "Sigmoid angle", "value": "30-40 deg" } ] }, { "subcategory": "Thorax and Abdomen Procedures", "title": "Biliary studies and GU studies", "must_know": [ "Surgical (operative) cholangiography is done in surgery with contrast injected into the biliary ducts to check for stones; ERCP uses an endoscope to cannulate the hepatopancreatic ampulla (of Vater), with pancreatitis as a key risk.", "Bile flow: right and left hepatic ducts form the common hepatic duct, which joins the cystic duct to form the common bile duct; it joins the pancreatic duct at the ampulla.", "IVU: check renal function and allergies, scout first, nephrogram at about 1 minute, timed images, then post-void (bladder emptying, prostate enlargement).", "IVU 30 degree posterior obliques: the kidney on the elevated side is parallel to the IR; the down-side kidney is perpendicular.", "Retrograde urography fills the collecting system through catheters placed by cystoscopy; it does not show kidney function.", "Cystography: bladder filled by gravity through a catheter; AP with 10-15 degrees caudal angle, 45-60 degree posterior obliques and lateral. Voiding cystourethrogram: AP for females, 30 degree RPO for males.", "Hysterosalpingography checks uterine shape and tube patency, scheduled about 7-10 days after the start of menses (before ovulation), using water-soluble iodinated contrast.", "Kidneys lie at about T12-L3 and are retroperitoneal; the right kidney sits slightly lower because of the liver." ], "memory_tip": null, "board_traps": [ "Ureteral compression in IVU is contraindicated with stones, trauma, recent surgery or an abdominal aortic aneurysm." ], "key_numbers": [ { "label": "IVU obliques", "value": "30 deg" }, { "label": "Cystogram obliques", "value": "45-60 deg" }, { "label": "Male VCUG", "value": "30 deg RPO" } ] }, { "subcategory": "Extremity Procedures", "title": "Fingers, thumb and hand", "must_know": [ "Fingers: PA with CR at the PIP joint; oblique and lateral with the finger parallel to the IR so the joint spaces open; include the entire digit and distal metacarpal.", "AP thumb: hand internally rotated so the back of the thumb lies on the IR (lower OID than PA); the PA hand naturally gives an oblique thumb; CR at the first MCP joint.", "PA hand: CR at the third MCP joint, fingers slightly spread.", "Oblique hand: 45 degree lateral rotation with fingers parallel to the IR to open the IP and MCP joints.", "Lateral hand (fan lateral or extended) shows anterior or posterior displacement of fractures and locates foreign bodies.", "Boxer's fracture is a fifth metacarpal neck fracture; Bennett fracture is at the base of the first metacarpal with dislocation.", "Bone age: PA of the left hand and wrist compared with a standard atlas (e.g., Greulich and Pyle)." ], "memory_tip": null, "board_traps": [ "Fingers resting on the IR in an oblique hand cause foreshortened phalanges and closed IP joints." ], "key_numbers": [] }, { "subcategory": "Extremity Procedures", "title": "Wrist and forearm", "must_know": [ "PA wrist: fingers flexed to put the wrist flat on the IR; CR at the midcarpal area.", "Lateral oblique wrist (45 degrees) shows the trapezium and scaphoid; lateral wrist superimposes the distal radius and ulna.", "Scaphoid (most commonly fractured carpal): PA with ulnar deviation and CR 10-15 degrees toward the elbow, or Stecher (CR or IR angled 20 degrees toward the elbow).", "Carpal canal (Gaynor-Hart, tangential inferosuperior): wrist hyperextended, CR 25-30 degrees to the long axis of the hand; shows the pisiform and hook of the hamate (carpal tunnel).", "Colles fracture: distal radius with posterior (dorsal) displacement from a fall on an outstretched hand; Smith fracture: anterior (volar) displacement.", "AP forearm: hand supinated so the radius and ulna are not crossed; include both the wrist and elbow joints.", "Carpals, proximal row lateral to medial then distal row: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate." ], "memory_tip": "Carpals: Some Lovers Try Positions That They Can't Handle.", "board_traps": [ "Pronating the hand for an AP forearm crosses the radius over the ulna.", "Radial deviation is for the medial carpals; ulnar deviation is for the scaphoid." ], "key_numbers": [ { "label": "Ulnar deviation angle", "value": "10-15 deg toward elbow" }, { "label": "Stecher", "value": "20 deg" }, { "label": "Gaynor-Hart", "value": "25-30 deg" } ] }, { "subcategory": "Extremity Procedures", "title": "Elbow", "must_know": [ "AP elbow: fully extended, hand supinated, epicondyles parallel to the IR.", "Lateral elbow: flexed 90 degrees, thumb up, humeral epicondyles perpendicular; the olecranon is in profile and the trochlear sulcus, capitulum and trochlea form concentric circles.", "Medial (internal) oblique 45 degrees shows the coronoid process in profile; lateral (external) oblique shows the radial head and neck free of the ulna and the capitulum.", "AP partial flexion (cannot fully extend): one image with the humerus parallel to the IR (distal humerus) and one with the forearm parallel (proximal forearm).", "Trauma axial laterals (Coyle): radial head with elbow flexed 90 degrees and CR 45 degrees toward the shoulder; coronoid with elbow flexed 80 degrees and CR 45 degrees away from the shoulder.", "A visible posterior fat pad on a true lateral means joint effusion and possible occult fracture (often the radial head in adults or supracondylar in children)." ], "memory_tip": "Rotate medially for the coronoid; rotate laterally for the radial head (the radius is the lateral bone).", "board_traps": [ "A lateral elbow not at 90 degrees can hide or create a fat pad sign." ], "key_numbers": [ { "label": "Coyle radial head", "value": "90 flex, 45 toward shoulder" }, { "label": "Coyle coronoid", "value": "80 flex, 45 away from shoulder" } ] }, { "subcategory": "Extremity Procedures", "title": "Humerus and shoulder", "must_know": [ "AP humerus: epicondyles parallel to the IR (external rotation); lateral: epicondyles perpendicular (internal rotation); transthoracic lateral for trauma using breathing technique.", "AP shoulder external rotation shows the greater tubercle in profile laterally; internal rotation shows the lesser tubercle in profile medially; neutral rotation is used for trauma.", "Grashey (posterior oblique 35-45 degrees toward the affected side) shows the glenoid in profile and an open glenohumeral joint.", "Inferosuperior axial (Lawrence): arm abducted about 90 degrees, CR 25-30 degrees medially through the axilla; shows the scapulohumeral relationship and coracoid.", "Scapular Y (PA oblique, anterior oblique 45-60 degrees): for dislocation; anterior dislocation (most common) puts the humeral head beneath the coracoid, posterior dislocation beneath the acromion.", "Supraspinatus outlet (Neer): scapular Y position with CR 10-15 degrees caudal; shows acromial spurs causing impingement.", "Hill-Sachs is a humeral head compression fracture and Bankart a glenoid rim injury, both from anterior dislocation." ], "memory_tip": null, "board_traps": [ "Never rotate the arm for internal/external views when a fracture or dislocation is suspected; use neutral AP and scapular Y or transthoracic lateral.", "Grashey rotates toward the affected side (posterior oblique), not away." ], "key_numbers": [ { "label": "Grashey", "value": "35-45 deg" }, { "label": "Scapular Y", "value": "45-60 deg" }, { "label": "Neer", "value": "10-15 deg caudal" }, { "label": "Lawrence", "value": "25-30 deg medial" } ] }, { "subcategory": "Extremity Procedures", "title": "Scapula, clavicle and AC joints", "must_know": [ "AP scapula: arm abducted 90 degrees to move the scapula lateral to the ribs; breathing technique blurs lung markings.", "Lateral scapula: anterior oblique so the scapula is perpendicular to the IR (the body of the scapula is seen in profile, free of the ribs).", "Clavicle: AP (or PA) plus AP axial with 15-30 degrees cephalic (or PA axial 15-30 degrees caudal) to project it above the ribs.", "AC joints: bilateral AP erect at 72 in SID, with and without equal weights (commonly 5-10 lb) strapped to the wrists to show separation.", "The patient must not hold the weights in the hands, since gripping tenses the shoulder muscles and can mask separation.", "AC joints are imaged erect; lying down reduces the separation." ], "memory_tip": null, "board_traps": [ "Weights are hung from the wrists, not held." ], "key_numbers": [ { "label": "AC joint SID", "value": "72 in" }, { "label": "Clavicle axial angle", "value": "15-30 deg" } ] }, { "subcategory": "Extremity Procedures", "title": "Toes, foot and calcaneus", "must_know": [ "AP toes: CR 10-15 degrees toward the heel (or a wedge under the foot) to open the joints; sesamoids are shown with a tangential projection.", "AP (dorsoplantar) foot: CR 10 degrees toward the heel, perpendicular to the metatarsals, centered at the base of the third metatarsal.", "Medial oblique foot (30-40 degrees): best for most tarsals, cuboid, sinus tarsi and the base of the fifth metatarsal; lateral oblique shows the navicular and first and second cuneiforms.", "Lateral foot is usually mediolateral with the foot dorsiflexed; weight-bearing AP and lateral assess the arches (pes planus) and Lisfranc injury.", "Calcaneus plantodorsal axial: foot dorsiflexed, CR 40 degrees cephalic to the long axis of the foot; plus a lateral.", "Jones fracture is at the proximal fifth metatarsal shaft just beyond the tuberosity; calcaneal fractures from falls often come with lumbar spine fractures." ], "memory_tip": null, "board_traps": [ "The medial oblique, not the lateral oblique, opens the cuboid and lateral tarsals." ], "key_numbers": [ { "label": "AP foot", "value": "10 deg toward heel" }, { "label": "Medial oblique foot", "value": "30-40 deg" }, { "label": "Calcaneus axial", "value": "40 deg cephalic" } ] }, { "subcategory": "Extremity Procedures", "title": "Ankle, tibia/fibula and knee", "must_know": [ "AP ankle: true AP with the long axis of the foot vertical; the lateral mortise is not open. Mortise view: leg rotated 15-20 degrees internally so the intermalleolar line is parallel to the IR and the whole mortise opens.", "Medial oblique ankle (45 degrees) opens the distal tibiofibular joint; lateral ankle puts the fibula over the posterior tibia. AP stress views (inversion/eversion) are done by the physician to show ligament tears.", "Tibia/fibula: include both the knee and ankle (diagonal on the IR or two images); a proximal fibula fracture with an ankle injury is a Maisonneuve fracture.", "AP knee CR angle by ASIS-to-tabletop measurement: under 19 cm, 3-5 degrees caudal; 19-24 cm, 0 degrees; over 24 cm, 3-5 degrees cephalic; slight internal rotation (3-5 degrees).", "Lateral knee: flexed 20-30 degrees, CR 5-7 degrees cephalic to superimpose the femoral condyles; epicondyles perpendicular.", "Medial (internal) oblique 45 degrees opens the proximal tibiofibular joint; lateral oblique superimposes the fibula on the tibia. Weight-bearing AP shows joint space narrowing.", "Intercondylar fossa: Holmblad (kneeling, femur 60-70 degrees to the table, CR perpendicular); Camp Coventry (prone, knee flexed 40-50 degrees, CR 40-50 degrees caudal); Beclere (supine, knee flexed 40-45 degrees, CR perpendicular to the lower leg).", "Patella: PA with heel rotated 5-10 degrees outward; Merchant (supine, knees flexed 40 degrees, CR 30 degrees caudal from horizontal, long SID); Settegast (knee flexed 90 degrees, CR 15-20 degrees) is not done until a transverse patellar fracture is ruled out." ], "memory_tip": null, "board_traps": [ "Too much knee flexion on a lateral pulls the patella into the intercondylar sulcus and can separate a patellar fracture.", "Medial oblique knee opens the proximal tibiofibular joint; lateral oblique closes it." ], "key_numbers": [ { "label": "Mortise", "value": "15-20 deg internal" }, { "label": "AP knee <19 cm", "value": "3-5 caud" }, { "label": "AP knee 19-24 cm", "value": "0" }, { "label": "AP knee >24 cm", "value": "3-5 ceph" }, { "label": "Lateral knee", "value": "20-30 flex, 5-7 ceph" } ] }, { "subcategory": "Extremity Procedures", "title": "Femur, long bone measurement and other studies", "must_know": [ "AP femur: leg internally rotated about 5 degrees (15-20 degrees when the hip is included unless fracture is suspected); include both joints on adults with two images if needed; use the heel effect with the cathode at the hip.", "Lateral femur: mediolateral for the distal femur; use a cross-table lateral for trauma.", "Long bone measurement (scanogram/orthoroentgenogram) measures leg-length difference: a ruler on the receptor and exposures over the hip, knee and ankle without patient movement, or a stitched digital image.", "Bone age: PA left hand and wrist compared with an atlas of standards for skeletal maturity.", "Bone surveys image the whole skeleton: metastatic survey for lytic or blastic lesions (e.g., multiple myeloma), and skeletal survey for suspected non-accidental trauma in young children.", "Signs that suggest non-accidental trauma: posterior rib fractures, metaphyseal corner fractures, and fractures at different stages of healing; report concerns according to facility policy and state law.", "Arthrography: sterile joint injection of contrast (iodinated, air, or gadolinium for MR arthrography) into joints such as the shoulder, knee, hip or wrist; check allergies and exercise the joint to spread contrast." ], "memory_tip": null, "board_traps": [ "Moving the patient between long bone measurement exposures invalidates the measurement." ], "key_numbers": [] } ] } ], "last_minute_review": [ "Verify identity with two identifiers and match the order to the clinical indication before every exposure.", "Battery = treating without consent; respondeat superior = employer liable; res ipsa loquitur = the thing speaks for itself.", "Epinephrine is the first-line drug for anaphylaxis; vasovagal = low BP with slow pulse (atropine, elevate legs).", "Suspected perforation: use water-soluble iodinated contrast, never barium.", "Schedule iodinated studies and barium enema before an upper GI.", "Airborne = N95 + negative pressure (TB, measles, varicella); C. difficile = soap and water.", "CPR: 100-120 compressions/min, at least 2 in deep, 30:2.", "Photoelectric = contrast and patient dose (rises with Z, falls with energy); Compton = scatter, fog and occupational dose.", "Maximum photon energy (keV) equals the kVp; tungsten K-characteristic needs about 70 kVp.", "Double the distance = one quarter the intensity; double the SID = four times the mAs.", "15% kVp increase ~ doubles receptor exposure.", "1 Gy = 100 rad; 1 Sv = 100 rem; x-ray radiation weighting factor = 1.", "Lymphocytes are the most radiosensitive blood cells; nerve and muscle cells the least.", "Organogenesis (about weeks 2-8) is the highest-risk period for malformations; under 50 mGy fetal dose has no proven effect (ACOG).", "NCRP #116: 50 mSv/yr occupational, 10 mSv x age cumulative, 1 mSv/yr public, 0.5 mSv/month embryo/fetus.", "Distance is the most effective protection; the patient is the main source of scatter.", "Fluoro limits: 88 mGy/min normal, 176 mGy/min high-level; 5-minute timer; SSD 38 cm fixed, 30 cm mobile.", "Total filtration 2.5 mm Al equivalent above 70 kVp; collimation within 2% of SID.", "Spatial resolution: small focal spot, short OID, long SID, no motion; MF = SID/SOD.", "Grid conversion: 5:1 = 2, 6:1 = 3, 8:1 = 4, 12:1 = 5, 16:1 = 6; upside-down grid = cutoff at both edges.", "DI = 10 log10(EI/target); +3 = double, -3 = half; a low Fuji S-value means overexposure.", "Quantum mottle = not enough mAs; saturation from gross overexposure cannot be fixed by processing.", "Window width = contrast; window level = brightness; DICOM for images, HL7 for text.", "Direct DR = amorphous selenium; indirect DR = scintillator (CsI) + amorphous silicon or CCD/CMOS.", "Chest: 72 in SID, PA erect, 10 posterior ribs, left lateral; decubitus: fluid side down, air side up.", "Free air: erect chest or left lateral decubitus abdomen.", "UGI: RAO and right lateral fill the duodenal bulb with barium; LPO puts air in the bulb.", "BE: posterior obliques open the up-side flexure, anterior obliques the down-side flexure.", "C-spine obliques: anterior oblique shows foramina closest to the IR; lumbar posterior oblique shows joints closest to the IR.", "Scaphoid: ulnar deviation; coronoid: medial oblique; radial head: lateral oblique; proximal tibfib joint: medial oblique knee." ] }