Your FREE ARRT Flashcards 2026 – 200+ Cards

American Registry of Radiologic Technologists — develops and administers the Radiography (R) exam and other radiologic credentials.

200 scored multiple-choice questions plus 30 unscored pilot questions = 230 total.

A scaled score of 75 on a 1–99 scale — not a percentage. Scaling equates difficulty across forms.

230 minutes (about 3 hours 50 minutes) of test time — roughly one minute per question.

Patient Care (33), Safety (50), Image Production (51), Procedures (66) = 200 scored.

The physician obtains informed consent. The technologist verifies it is documented and that the patient understands the procedure.

Failure to act as a reasonably prudent technologist would under the circumstances, resulting in harm.

Assault = threatening or attempting a procedure without consent. Battery = actually touching/performing it without consent.

Autonomy (right to decide), beneficence (do good), nonmaleficence (do no harm), and justice (fairness).

Verify a patient with two identifiers (e.g., name + date of birth) and confirm the correct exam and side before any exposure.

The minimum infection-control practices used on every patient: hand hygiene, PPE as needed, respiratory hygiene, safe injection, and cleaning equipment.

Medical asepsis = clean technique that reduces microorganisms. Surgical asepsis = sterile technique that eliminates them (for invasive procedures).

Gown + gloves on entry. For MRSA, VRE, and C. difficile (use soap and water for C. diff — alcohol does not kill spores).

Surgical mask within ~6 ft. For influenza, pertussis, and mumps.

N95 respirator + negative-pressure room. For tuberculosis, measles, and varicella (chickenpox).

About 120/80 mmHg (systolic <120, diastolic <80).

60–100 beats per minute.

12–20 breaths per minute.

About 98.6°F (37°C).

95–100%.

Ionic = high osmolality, more reactions. Nonionic = low osmolality, far better tolerated and standard for intravascular use.

Positive contrast (iodine, barium) absorbs more x-rays and appears bright. Negative contrast (air/gas) is radiolucent and appears dark.

Use barium sulfate for routine GI studies, but switch to a water-soluble iodinated agent if perforation is suspected (leaked barium causes peritonitis).

Mild (nausea, hives → observe), moderate (marked urticaria, mild bronchospasm → treat), severe (laryngeal edema, anaphylaxis → emergency, epinephrine).

Ask about prior reaction, renal function, diabetes/metformin, and asthma/allergies; have emergency equipment ready.

Federal law protecting the privacy and security of patient health information; only share on a need-to-know basis.

Unlawful restriction of a patient's freedom of movement (e.g., improper use of restraints).

American Society of Radiologic Technologists — the professional society that publishes practice standards for the field.

Avoid having radiology staff hold patients. If a holder is needed, use a non-occupational person in a lead apron and gloves, out of the primary beam.

Supine with the head lower than the feet; used for some procedures and to manage hypotension.

'Let the master answer' — the employer can be held legally liable for the negligent acts of an employee performed within the scope of employment.

'The thing speaks for itself' — negligence is obvious from the circumstances (e.g., a retained foreign object).

Implied consent is assumed in an emergency when the patient can't respond. Informed consent requires the physician to explain risks, benefits, and alternatives.

The AHA document (formerly the Patients' Bill of Rights) outlining what patients should expect: privacy, information, involvement in care, and respect.

Pathogen → reservoir → portal of exit → mode of transmission → portal of entry → susceptible host. Break any link to stop spread.

Protective isolation that shields an immunocompromised patient FROM the environment, rather than protecting others from the patient.

Hand hygiene is the single most effective way to prevent the spread of infection.

Contrast leaking into the tissues around the IV instead of the vein; stop the injection, elevate, and apply cold/warm compresses per protocol.

Record the contrast agent, dose/amount, route, site, time, and any reaction.

BUN, creatinine, and eGFR — to assess kidney function and the risk of contrast-induced nephropathy.

Improperly altering exposure indicators or cropping/masking anatomy to hide error is an ARRT ethics violation.

Semi-sitting (head of bed elevated ~45–60°); eases breathing for patients in respiratory distress.

Photon is totally absorbed by an inner-shell electron — no scatter. Builds image contrast, depends on Z³ and lower kVp, and increases patient dose.

Photon ejects an outer-shell electron and continues deflected. The scatter fogs the image (lowers contrast) and is the main occupational dose hazard.

'Braking' radiation — a high-speed electron is decelerated/deflected by the nucleus, emitting an x-ray. The dominant source of the diagnostic beam.

An inner-shell electron is ejected, an outer electron fills the gap, and a photon of energy specific to the target element is released.

High-energy, short-wavelength ionizing electromagnetic radiation; they travel in straight lines and cannot be focused by a lens.

Only about 1% of the electrons' kinetic energy becomes x-rays; ~99% becomes heat at the anode.

Boiling off of electrons from the heated cathode filament; these electrons are then driven across to the anode.

The photoelectric effect — the photon's full energy is absorbed by the tissue.

Compton scatter predominates at the higher kVp range used in diagnostic radiography.

Gray (Gy); 1 Gy = 100 rad. Energy deposited per unit mass of tissue.

Sievert (Sv); 1 Sv = 100 rem. Absorbed dose weighted for biological harm; the unit used for dose limits.

Becquerel (Bq); 1 curie (Ci) = 3.7 × 10¹⁰ Bq.

The traditional unit of exposure/air kerma; SI now uses the gray (air kerma). ≈ 1 R = 0.00876 Gy air kerma.

Cells are most radiosensitive when highly mitotic, undifferentiated, and have a long mitotic future.

Embryo/fetus, bone marrow (blood-forming), intestinal crypt cells, and reproductive cells.

Nerve and muscle cells (highly differentiated, non-dividing).

Tissue reactions with a threshold dose; severity increases with dose (skin erythema, cataracts, sterility).

Effects with no threshold; probability (not severity) increases with dose (cancer, heritable genetic effects).

The assumption that any dose, however small, carries some stochastic risk — the basis for minimizing all exposure.

The amount of energy a radiation deposits per unit path length; high-LET radiation causes more biological damage.

A comparison of a radiation's biological damage to that of a reference radiation for the same dose; rises with LET.

Direct: radiation hits DNA itself. Indirect: radiation ionizes water, forming free radicals that damage DNA (most common in tissue).

The hematopoietic (bone marrow) system, because blood-forming cells are highly radiosensitive.

Photoelectric absorption increases roughly with the cube of atomic number (Z³), which is why bone and contrast media appear bright.

Bremsstrahlung gives a continuous spectrum (0 up to peak kVp); characteristic radiation gives discrete energies specific to the target.

Tungsten (Z=74) is the standard anode target — high atomic number (efficient x-ray production) and high melting point (heat tolerance).

Tungsten K-characteristic x-rays only appear above about 70 kVp, because the K-shell binding energy is ~69.5 keV.

Increases with the cube of atomic number and decreases sharply with photon energy (roughly Z³/E³); dominant at low diagnostic energies.

Compton scatter is essentially independent of atomic number (it depends on electron/tissue density) and dominates across most of the diagnostic range.

A low-energy interaction in which the photon changes direction without losing energy; a minor contributor to image fog at low kVp.

Kinetic energy released per unit mass of air, measured in gray; the modern quantity that replaces the roentgen for exposure.

Direct: radiation ionizes DNA itself. Indirect: radiation ionizes water into free radicals that then damage DNA — the more common path in tissue.

The lymphocyte — highly radiosensitive and an early indicator of radiation exposure, even though it is not actively dividing.

Genetic (heritable) effects occur in reproductive cells and affect offspring; somatic effects occur in the exposed individual's other body cells.

A factor applied to each organ's dose to reflect its relative radiosensitivity when calculating whole-body effective dose.

The minimum dose required to produce a deterministic effect; below it, the effect does not occur.

As Low As Reasonably Achievable — keep every radiation dose to patients, staff, and the public as low as possible while still getting a diagnostic image.

Intensity is inversely proportional to the square of distance: I₁/I₂ = (D₂)²/(D₁)². Doubling distance cuts intensity to one quarter.

Time, distance, and shielding. Distance is the most effective because of the inverse square law.

50 mSv/yr whole-body effective dose; cumulative lifetime limit = 10 mSv × age in years (NCRP-116).

1 mSv/yr for continuous/frequent exposure (5 mSv/yr infrequent).

5 mSv total over the entire gestation, and no more than 0.5 mSv in any single month.

150 mSv/yr (NCRP-116).

500 mSv/yr (occupational, NCRP-116).

Every radiographer; it is the guiding philosophy for protecting patients, staff, and the public.

Distance — by the inverse square law, doubling the distance cuts dose to one quarter.

Dose is directly proportional to time in the radiation field; minimize exposure time.

Use lead aprons, thyroid shields, gloves, and barriers to absorb radiation when distance cannot be increased.

new mAs = old mAs × (new SID² / old SID²). Going 40→80 inch SID needs 4× the mAs.

10 mSv × the worker's age in years (NCRP-116).

Optically stimulated luminescence badge — the current standard personnel monitor; accurate and re-readable.

Film badge (older), TLD (thermoluminescent), and pocket dosimeter (instant reading) are alternative personnel monitors; OSL is now standard.

At collar level on the outside of the lead apron.

A declared-pregnant worker wears a second badge at waist level under the lead apron to monitor fetal dose.

Restricting the beam to the area of interest; reduces patient dose and scatter and improves contrast.

Aluminum removes low-energy photons that would only add patient skin dose, hardening the beam.

2.5 mm aluminum equivalent for tubes operating above 70 kVp (21 CFR 1020.30).

Typically 0.5 mm lead equivalent for protective aprons.

Inherent = filtration built into the tube/housing. Added = the aluminum sheet plus the collimator mirror; the two sum to total filtration.

Primary = the useful beam from the tube. Secondary/scatter = radiation deflected by the patient — the main staff hazard.

Scatter radiation from the patient, especially during fluoroscopy and mobile/portable exams.

Every repeat doubles patient dose; correct one cause at a time and avoid unnecessary repeats (ALARA).

Contact/area shielding of patients is now applied per current facility and professional-society policy rather than routinely for every exam.

A fixed protective barrier (often leaded glass) behind which the operator stands to make the exposure.

Regulatory dose limits are maximums; ALARA still requires keeping actual dose well below them.

A barrier in the path of the useful (primary) beam (e.g., the wall the beam points at); thicker than a secondary barrier.

A barrier protecting against leakage and scatter radiation only (e.g., the control-booth barrier); thinner than a primary barrier.

Radiation escaping the tube housing must not exceed 100 mR/hr at 1 meter.

Declaration of pregnancy is voluntary and in writing; it activates the 0.5 mSv/month and 5 mSv gestational fetal limits and a second monitoring badge.

An obsolete rule that elective abdominal/pelvic exams of childbearing-age women be done within 10 days of menses onset; replaced by pregnancy-status screening.

A whole-body dose estimate that weights each organ's dose by its radiosensitivity; used to compare risk across different exposures.

Campaigns promoting dose optimization — Image Gently for pediatrics and Image Wisely for adults.

A smaller field produces less scatter radiation, and less scatter means higher image contrast — as well as lower patient dose.

A higher half-value layer means a 'harder,' more penetrating beam and confirms adequate filtration.

Surface shields don't block internal scatter (the main out-of-field dose), can trigger the AEC to raise dose, and may obscure anatomy and cause repeats.

A longer source-to-skin distance lowers patient skin entrance dose, which is why a minimum SSD is enforced (e.g., for fluoroscopy and mobile units).

Beam quality (energy/penetration) and the scale of radiographic contrast. Higher kVp = more penetration, lower (longer-scale) contrast.

Beam quantity (number of photons) and receptor exposure (density). Directly proportional: double mAs = double exposure.

mAs = mA × exposure time (seconds).

Increasing kVp by 15% has the same effect on receptor exposure as doubling the mAs. Raise kVp 15% and halve mAs to cut dose at constant exposure.

Grainy image noise from too few photons (mAs too low). Fix it with more mAs, not more kVp.

Off-level, off-center, off-focus (wrong SID range), and upside-down focused grid — all absorb useful primary beam.

kVp. Higher kVp = lower (longer-scale) contrast with more shades of gray.

mAs, which is directly proportional to receptor exposure.

Short scale = high contrast, few densities (low kVp). Long scale = low contrast, many densities (high kVp).

The ability to image small, closely spaced structures (detail/sharpness). Best with a small focal spot, long SID, and short OID.

The ratio of useful image signal to noise; raising mAs increases SNR (cleaner image) but adds dose.

For body parts thicker than about 10 cm or exposures above roughly 60 kVp, where scatter is significant.

Height of the lead strips ÷ the distance between them. Higher ratios remove more scatter but need more exposure.

The factor by which exposure must increase when a grid is used, to compensate for primary beam the grid absorbs.

Increasing OID so scatter misses the receptor — an alternative to a grid that reduces scatter (but increases magnification).

MF = SID / SOD (also image size ÷ object size), where SOD = SID − OID.

Keep the part close to the receptor (low OID) and use a long SID.

Size distortion (magnification) comes from distance. Shape distortion (foreshortening/elongation) comes from tube–part–receptor alignment.

The blurred, unsharp edge of a structure; reduced by a small focal spot, long SID, and short OID.

Uses a photostimulable phosphor imaging plate that is scanned by a separate reader after exposure.

Uses a flat-panel detector that sends the image directly and immediately — no cassette to process.

A number reported by digital systems indicating the radiation exposure the receptor received.

How far the actual exposure deviated from target: near 0 = correct, positive = overexposed, negative = underexposed.

A graph of the pixel-value distribution the system uses to apply the look-up table (LUT) and render the image.

Processing rescales the image to look correct, so EI/DI — not appearance — is how you confirm an ALARA-appropriate dose.

How efficiently a detector converts incident x-rays into image signal; higher DQE = better image at lower dose.

Ghosting/lag, dead pixels, grid-line (moiré) artifact, and dust/scratch artifacts on CR plates.

Tube angled across the lead strips → uniform underexposure (overall light image).

Central ray laterally off the grid midline → uniform underexposure.

SID outside the focused grid's focal range → cutoff toward the periphery (light edges).

Strips angle the wrong way → severe peripheral cutoff with a light band at the sides.

kVp is the controlling factor: high kVp = long scale (low contrast, many grays); low kVp = short scale (high contrast).

Gradual overexposure on digital systems because images still look acceptable; the deviation index (DI) detects it.

Improved by a small focal spot, long SID, and short OID; degraded by motion, large focal spot, and increased OID.

Patient motion is the most common cause of unsharpness; reduce it with short exposure times, clear instructions, and immobilization.

Different mA and time combinations that give the same mAs produce the same receptor exposure (e.g., 200 mA × 0.1 s = 100 mA × 0.2 s = 20 mAs).

The number of grid lines per inch (or cm); higher frequency grids are less visible on the image.

Increasing OID lets scatter miss the receptor (an alternative to a grid) but increases magnification — so a longer SID is used to compensate.

Post-processing controls: window width adjusts displayed contrast; window level adjusts displayed brightness.

A processing map that converts raw detector values into the displayed brightness/contrast appropriate for the body part.

The number of shades of gray a system can display; higher bit depth gives finer contrast resolution.

If the system mis-identifies the data of interest (wrong body part menu, collimation error), the image can be too dark or too light despite correct technique.

A wavy grid-line pattern from a stationary grid whose frequency interferes with the CR scanning frequency.

Beam is more intense on the cathode side, less on the anode side. Place the thicker body part toward the cathode.

An angled anode makes the effective focal spot smaller than the actual focal spot — sharper detail while spreading heat.

The negative side: filament + focusing cup; emits electrons by thermionic emission and focuses them at the anode.

The positive side: the angled tungsten target the electrons strike, where x-rays (and heat) are produced.

By line focus, the effective (projected) focal spot is smaller than the actual focal spot where electrons land.

Small focal spot = sharper detail but limited heat loading. Large focal spot = higher techniques but less sharpness.

A steeper (smaller) anode angle gives a smaller effective focal spot but a more pronounced anode heel effect.

Place the thicker/denser anatomy toward the cathode (more intense) side — e.g., the thoracic spine with the abdomen at the cathode.

Converting alternating current to the unidirectional current the x-ray tube requires.

Single-phase = high ripple, three-phase = lower, high-frequency = lowest ripple (near-constant potential), most efficient output.

The current standard: lowest ripple, most consistent and efficient x-ray output, compact design.

Ion chambers behind the receptor that terminate the exposure once a preset receptor exposure is reached.

A safety limit on the maximum exposure time/mAs in case the AEC fails to terminate.

Center the anatomy of interest over the active AEC cell(s); off-centering causes incorrect exposure.

A QC test confirming the actual tube kVp matches the selected value within tolerance.

The same exposure technique produces the same output every time.

Output (mGy/mAs) stays proportional and consistent across the different mA stations.

The thickness of aluminum that reduces beam intensity to half; a measure of beam quality and adequate filtration.

A QC test ensuring the light field matches the actual x-ray field within tolerance (±2% of SID).

The negatively charged cup around the filament that narrows the electron stream onto the focal spot.

A measure of heat load on the anode; high-frequency generators produce more heat per technique, limited by the tube rating chart.

Spreads heat over a larger track so the tube can tolerate higher exposures than a stationary anode.

Filament current (mA): more heating current boils off more electrons, raising the tube current and the quantity of x-rays.

The cloud of electrons around the filament that limits how many more electrons can be emitted at low kVp.

Spreads the heat of the electron stream over a large focal track so the tube tolerates higher exposures without melting.

Half-wave uses only the positive half of the AC cycle (wasteful); full-wave flips the negative half to also produce x-rays (more efficient).

Buttons (e.g., −2 to +2) that adjust the preset receptor exposure up or down from the default to fine-tune image brightness.

The shortest exposure the AEC can produce; very thin parts may overexpose if their needed exposure is below it.

Confirms that output (mGy per mAs) stays consistent and proportional as you change between mA stations.

Confirms that the same selected technique gives the same output every time it is repeated.

Must agree within ±2% of the SID; verifies the collimator light accurately shows where the beam will go.

Display monitors are calibrated to the DICOM Grayscale Standard Display Function and checked for luminance and uniformity.

A chart showing the maximum safe combinations of kVp, mA, and time for a tube to prevent overheating/damage.

Projection = the path of the central ray through the body (AP, PA, oblique). Position = the patient's body placement (lateral, decubitus).

The most central, least divergent portion of the beam; centered and angled to the part and receptor to minimize distortion.

AP: beam enters anterior, exits posterior. PA: beam enters posterior, exits anterior (used for the routine chest).

The average body type (~50% of patients); the reference for standard positioning and technique.

Massive, broad build (~5%); organs sit high and horizontal — wide thorax and abdomen.

Very slender, frail build (~10%); organs sit low and very vertical (long and narrow).

Slender, lighter build (~35%); organs slightly lower and more vertical than sthenic.

72 inches (180 cm) to minimize heart magnification.

Upright, full inspiration (suspend on the 2nd breath), scapulae rolled off the lung fields, no rotation; CR to T7.

Left lateral (left side to receptor) to minimize heart magnification; arms raised, CR to T7.

Upright shows air–fluid levels and lets the diaphragm drop; full inspiration expands the lungs for maximal aeration.

AP supine projection of kidneys, ureters, and bladder; CR perpendicular to the iliac crest, exposure on expiration.

Shows air–fluid levels and free air under the diaphragm; CR ~2 inches above the iliac crest to include the diaphragm.

Three projections: AP/PA, oblique, and lateral, with the part close to the receptor and a small focal spot.

AP oblique with the leg/foot internally rotated 15–20° to open the mortise joint evenly.

A special wrist view (ulnar deviation / Stecher method) to better demonstrate the scaphoid for suspected fracture.

Central ray angled 15–20° cephalad to open the intervertebral disk spaces.

Shows C1–C2 (the dens); CR perpendicular between the upper and lower incisors with the mouth open.

45° rotation; AP obliques (CR 15° cephalad) open the intervertebral foramina on the side farthest from the receptor.

45° rotation demonstrates the zygapophyseal joints; the 'Scottie dog' appearance — neck = pars interarticularis.

Internally rotate the feet/legs 15–20° to overcome femoral-neck anteversion and show the necks in profile.

Do NOT rotate the legs — rotation could displace the fracture; image as-is.

Orbitomeatal line (outer canthus → EAM) and infraorbitomeatal line (inferior orbit → EAM); OML is ~7–8° steeper than IOML.

A PA axial facial-bone/sinus view that projects the petrous ridges below the maxillary sinuses.

An AP axial skull view (CR 30° caudad to OML) demonstrating the occipital bone and foramen magnum.

A PA axial skull/sinus view (CR 15° caudad) demonstrating the frontal bone and ethmoid sinuses.

Patient lies on their side with a horizontal beam; shows air–fluid levels and free air (e.g., left lateral decubitus abdomen).

AP with CR 0–5° cephalad (varies with the patient's pelvis-to-tabletop measurement) to open the joint.

External rotation = true AP (greater tubercle in profile). Internal rotation = lateral humerus (lesser tubercle in profile).

PA (CR to 3rd MCP), 45° oblique (fingers separated), and lateral 'fan' to assess fractures and foreign bodies.

Dorsoplantar with CR 10° toward the heel (posteriorly) to open the tarsometatarsal joints.

Anatomical side markers are a legal requirement and prevent wrong-side errors; place them within the collimated field.

CR perpendicular to the level of interest (often L3 / iliac crest); a small caudal angle may be needed if the spine sags.

PA reduces heart magnification (heart is closer to the receptor) and reduces breast/thyroid dose.

Always mark which side is up and use a horizontal beam, so free air and air–fluid levels are demonstrated.

Anterior obliques (LAO/RAO) place that anterior side closest to the IR; posterior obliques (LPO/RPO) place that posterior side closest to the IR.

The body part as seen from the perspective of the image receptor (the opposite of the projection's entrance side).

Recumbent = lying down; supine = lying on the back (face up); prone = lying face down.

45° obliques open the intervertebral foramina; posterior obliques (RPO/LPO) show the foramina farthest from the IR (CR 15° cephalad).

On a lumbar oblique: ear = superior articular process, eye = pedicle, nose = transverse process, neck = pars interarticularis, front leg = inferior articular process.

A 60–72 inch (longer) SID is used for the lateral cervical spine to reduce magnification from the increased OID.

Defer the open-mouth (and any rotation) on a suspected unstable C-spine trauma; obtain a cross-table (horizontal-beam) lateral first.

A hip/pelvis projection with the knees flexed and abducted; shows the femoral heads/necks in a lateral profile (non-trauma only).

A horizontal-beam lateral used for a suspected hip fracture, because the affected leg must not be moved.

Posterior oblique that opens the glenohumeral joint space, demonstrating it without bony overlap.

CR angled 40° cephalad to the long axis of the foot to show the calcaneus without superimposition.

Flex the elbow 90° with the humerus and forearm on the same plane; demonstrates the fat pads (a sign of effusion/fracture).

The sternoclavicular joints should be symmetric and equidistant from the spine — asymmetry indicates rotation.

Most bony anatomy is imaged in at least two projections roughly 90° apart so fractures and alignment aren't missed.

Anatomical R/L lead markers must be placed within the collimated field at the time of exposure — they are a legal record, not added later.