ARRT Radiography terminology

The ARRT Radiography Boards glossary, A to Z.

Q: How many terms are tested on the ARRT Radiography Boards?

The ARRT Radiography Content Specifications include roughly 250–300 distinct technical terms across patient care, image production, procedures, and safety. Our glossary covers the 185 highest-yield terms, the ones that have appeared on past administrations of the registry and that anchor the conceptual content in the 2025 Content Specifications.

Q: Should I memorize all the radiography terminology?

You don't need to memorize every term verbatim. You need to understand each one well enough to recognize it in a question stem and in the rationale. The most-tested categories of terms are: positioning vocabulary (projection, position, angulation), fracture types (Colles, Boxer, Salter-Harris), legal terms (tort, negligence, four conditions of consent), photon interactions (photoelectric, Compton), and dose units (Gy, Sv, rad, rem). Master those families first.

Q: How is this glossary organized?

Alphabetically A through Z, with cross-references to the chapter where each term is taught in depth. 185 unique terms across all 27 chapters of the curriculum. Use Cmd-F or Ctrl-F to search the page for any term you encounter in a practice question.

Plain-English definitions for 185 of the most-tested terms on the ARRT Radiography registry. Each term is cross-referenced to the chapter where it’s taught in full.

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10 Posterior Ribs Rule: On a properly inspired PA chest, at least 10 posterior ribs should be visible above the diaphragm. See Chest X-Ray for ARRT → Practice questions →
10-Day Rule: Older NCRP guidance: elective radiography of women of childbearing age within 10 days of menstrual onset. Modern practice favors the 28-day rule plus informed consent. See Radiation Protection for ARRT → Practice questions →
15% Rule: A 15% increase in kVp doubles density; halve mAs to compensate. A 15% decrease halves density; double mAs. See Image Acquisition → Practice questions →
30% Density Rule: A change in mAs must be at least 30% to produce a visible difference in density. See Image Quality and Technical Factors → Practice questions →

A

ABS (Automatic Brightness Stabilization): Fluoroscopic feedback loop that adjusts kVp and mA to hold output brightness constant. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →
AC Joint Separation: Acromioclavicular ligament injury. Imaged with weighted and unweighted bilateral AP projections of the shoulders. See Upper Extremity Positioning → Practice questions →
Additive Pathology: Disease that increases tissue density. Pneumonia, pleural effusion, ascites, Paget's disease. Increase technique. See Pathology, Artifacts, and Processor Errors → Practice questions →
AEC (Automatic Exposure Control): Three-chamber sensor that terminates exposure when target radiation reaches the IR. Centering is critical. See Image Acquisition → Practice questions →
Air Gap Technique: Use of 6–10 inch OID instead of a grid to absorb scatter. Lower patient dose, more magnification. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →
Air-Fluid Level: Horizontal interface between air and fluid in a body cavity. Diagnostic of acute sinusitis when present in a sinus. See Paranasal Sinus Radiography → Practice questions →
Airborne Precautions: N95 respirator + negative-pressure isolation room. Used for tuberculosis, measles, varicella (chickenpox). See Infection Control for ARRT Radiographers → Practice questions →
ALARA: As Low As Reasonably Achievable. The operational principle of all radiation protection. See Radiation Protection for ARRT → Practice questions →
Anaphylaxis: Severe systemic allergic reaction with bronchospasm, hypotension, and laryngeal edema. Treat with epinephrine immediately. See Emergencies → Practice questions →
Anatomic Position: Standing erect, palms forward, feet pointing ahead. The universal reference for all directional terminology. See Positioning Foundations → Practice questions →
Anode: Positive electrode (the target). Tungsten-rhenium rotating disk in modern diagnostic tubes. See X-Ray Tube and Equipment for ARRT → Practice questions →
Anode Heel Effect: Beam intensity is greater on the cathode side of the field due to anode self-absorption on the anode side. See X-Ray Tube and Equipment for ARRT → Practice questions →
Aortography: Contrast imaging of the thoracic or abdominal aorta. Femoral or translumbar approach. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →
AP Axial Cervical: AP projection with 15–20° cephalic central-ray angulation. Demonstrates C3 through C7 with the intervertebral disk spaces open. See Spine and Bony Thorax Positioning → Practice questions →
AP Mortise: Ankle projection with 15–20° internal rotation. Opens the talocrural joint space free of overlap. See Lower Extremity Positioning → Practice questions →
ARRT Rule 21: Duty to report violations by other technologists or candidates. Failing to report is itself a violation. See Foundations of Practice → Practice questions →
ARRT Rule 22: Duty to immediately self-report any error in patient care, regardless of whether the patient was injured. See Foundations of Practice → Practice questions →
Autotransformer: Variable-ratio transformer that selects kVp by tapping different points along a single coil. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →
Avulsion Fracture: A small piece of bone is pulled away by the attached ligament or tendon. Common at insertions. See Trauma Radiography for ARRT → Practice questions →

B

Barium Sulfate: Positive contrast used in GI imaging. Coats mucosa, distends lumen. Contraindicated when perforation is suspected. See GI and Hepatobiliary Procedures → Practice questions →
Battery: Unauthorized physical contact, for example, performing an exam after a patient has refused. Distinct from assault, which is the threat alone. See Foundations of Practice → Practice questions →
Beam-Light Field Alignment: Tolerance: within 2% of SID. At 40 inches, beam edge can deviate up to 0.8 inches from light field edge. See Radiography Quality Control → Practice questions →
Bennett Fracture: Fracture-dislocation at the base of the first metacarpal. Often unstable, requires orthopedic management. See Upper Extremity Positioning → Practice questions →
Body Mechanics: Lifting and movement principles that protect the radiographer's spine: legs not back, wide base, load close to center. See Patient Communication and Care for ARRT → Practice questions →
Boxer's Fracture: Fracture of the 5th metacarpal neck. Common from punching with a closed fist. See Upper Extremity Positioning → Practice questions →
Breathing Technique: Slow, shallow breathing during exposure to blur overlying lung markings on T-spine and sternum laterals. See Spine and Bony Thorax Positioning → Practice questions →
Bremsstrahlung: X-ray photon produced when an incident electron is decelerated by the nucleus of an anode atom. Continuous energy spectrum. See Radiation Physics and Radiobiology for ARRT → Practice questions →
Brightness Gain: Image intensifier gain. Product of minification gain and flux gain. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →
Bucky Factor: mAs multiplier required to compensate for grid absorption. 8:1 grid = 4× mAs; 12:1 = 5× mAs; 16:1 = 6× mAs. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →

C

C-A-B Sequence: Compressions–Airway–Breathing. The current AHA basic life support order, replacing the older A-B-C. See Emergencies → Practice questions →
Caldwell Method: PA skull with CR 15° caudad to OML. Demonstrates frontal bone and anterior ethmoid air cells. See Skull, Face, and TMJ Positioning → Practice questions →
Caldwell PA: PA sinus projection with 15° caudad CR to OML. Demonstrates frontal and anterior ethmoid sinuses. See Paranasal Sinus Radiography → Practice questions →
Camp-Coventry Method: PA knee with 40–50° flexion and 40–50° caudad central ray. Alternative for the intercondylar fossa. See Lower Extremity Positioning → Practice questions →
Cardiac Catheterization: Catheter-based imaging of coronary arteries via femoral or radial artery access. Cine imaging during contrast injection. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →
Cardiothoracic Ratio: Ratio of heart width to chest width. Greater than 50% suggests cardiomegaly. Valid only on PA chest. See Chest X-Ray for ARRT → Practice questions →
Cathode: Negative electrode containing the filament(s). Source of electrons via thermionic emission. See X-Ray Tube and Equipment for ARRT → Practice questions →
Cerebral Angiography: Contrast study of carotid and vertebral arteries. Used for aneurysm, AVM, and acute stroke workup. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →
Characteristic Radiation: X-ray photon produced when a K-shell electron is ejected and replaced by an outer-shell electron. Discrete energy specific to the anode material (tungsten K-shell binding ~69 keV; emitted characteristic photons ~57-69 keV). See Radiation Physics and Radiobiology for ARRT → Practice questions →
Coherent Scatter: Low-energy photon interacts with the atom and scatters with no energy loss. Minor at diagnostic energies. See Radiation Physics and Radiobiology for ARRT → Practice questions →
Colles Fracture: Transverse fracture of the distal radius with dorsal (posterior) displacement of the distal fragment. From a fall on outstretched hand. See Upper Extremity Positioning → Practice questions →
Collimation: Restriction of the beam to the area of clinical interest. Reduces scatter, improves contrast, lowers patient dose. See Image Acquisition → Practice questions →
Comminuted Fracture: Fracture in which the bone is broken into three or more fragments. See Trauma Radiography for ARRT → Practice questions →
Compound Fracture: Fracture in which the bone breaks through the skin (open). Distinct from a closed/simple fracture. See Trauma Radiography for ARRT → Practice questions →
Compton Scatter: Photon transfers partial energy to outer-shell electron and scatters at lower energy. Source of patient and operator dose. See Radiation Physics and Radiobiology for ARRT → Practice questions →
Contact Precautions: Gown, gloves, dedicated equipment. Used for MRSA, VRE, C. diff, scabies, and other contact-transmitted organisms. See Infection Control for ARRT Radiographers → Practice questions →
Contrast: Range of densities (gray scale) on the image. Controlled primarily by kVp. See Image Quality and Technical Factors → Practice questions →
Coronal Plane: Vertical plane that divides the body into anterior and posterior portions. Also called the frontal plane. See Positioning Foundations → Practice questions →
Coronary Angiography: Imaging of the LAD, circumflex, and right coronary arteries. Performed during cardiac cath. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →
Costophrenic Angle: Sharp angle where diaphragm meets chest wall on PA chest. Blunting indicates pleural effusion. See Chest X-Ray for ARRT → Practice questions →
Cross-Table Lateral: Lateral projection performed with a horizontal central ray and the patient supine. Used for trauma C-spine and hip imaging. See Trauma Radiography for ARRT → Practice questions →
Cross-Table Lateral C-Spine: Horizontal-beam lateral with the patient supine. The first projection in any C-spine trauma series. See Spine and Bony Thorax Positioning → Practice questions →
Cyanosis: Bluish discoloration of skin and mucous membranes from low oxygen saturation. A clinical sign, not a diagnosis. See Patient Communication and Care for ARRT → Practice questions →
Cycle of Infection: The six-link chain (agent, reservoir, portal of exit, transmission, portal of entry, susceptible host). Breaking any link stops infection. See Infection Control for ARRT Radiographers → Practice questions →

D

Danelius-Miller Method: Cross-table axiolateral hip projection. Used for trauma when the patient cannot rotate the affected leg. See Lower Extremity Positioning → Practice questions →
Density: Overall blackness of the image. Controlled primarily by mAs (directly proportional). See Image Quality and Technical Factors → Practice questions →
Destructive Pathology: Disease that decreases tissue density. Pneumothorax, emphysema, osteoporosis. Decrease technique. See Pathology, Artifacts, and Processor Errors → Practice questions →
Deterministic Effect: Threshold effect (skin erythema, cataracts). Severity increases with dose above the threshold. See Radiation Physics and Radiobiology for ARRT → Practice questions →
Diagnostic Quality Checklist: Positioning, technical factors, anatomy, no artifacts, correct markers. Apply systematically to every image. See Image Evaluation and Grid Artifacts → Practice questions →
Distortion: Misrepresentation of size or shape. Size = magnification (SID/OID). Shape = elongation/foreshortening (CR angulation). See Image Quality and Technical Factors → Practice questions →
Don't Move Rule: In trauma, move the tube and IR, never the patient or the injured part. Adapt the projection, not the anatomy. See Trauma Radiography for ARRT → Practice questions →
Dose Creep: Gradual unmonitored rise in technique factors over time as technologists overexpose to avoid mottle. See Computed Radiography and Digital Workflow → Practice questions →
Double-Contrast Study: Combination of barium + air/CO2. Barium coats the mucosa, gas distends the lumen for maximum mucosal detail. See GI and Hepatobiliary Procedures → Practice questions →
Droplet Precautions: Surgical mask + eye protection within 3–6 feet. Used for influenza, pertussis, mumps, meningococcal disease. See Infection Control for ARRT Radiographers → Practice questions →
DSA (Digital Subtraction Angiography): Subtraction technique that removes overlying bone and tissue, leaving only the contrast-filled vessels. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →

E

Elongation: Shape distortion from CR or IR being angled relative to the part. Projects longer than reality. See Image Quality and Technical Factors → Practice questions →
Erect Position: Patient sitting or standing upright. Required for sinus radiography to demonstrate air-fluid levels. See Paranasal Sinus Radiography → Practice questions →
Exposure Index: CR/DR numeric metric of receptor exposure. For the standardized (IEC) EI, a higher EI means more exposure (overexposure) and a lower EI means underexposure; some legacy vendor indices (e.g., Fuji S) are inverse, so always check the manufacturer convention. See Pathology, Artifacts, and Processor Errors → Practice questions →
Exposure Index (EI): Manufacturer-specific or IEC-standardized estimate of receptor exposure. Tracks under- and overexposure. See Computed Radiography and Digital Workflow → Practice questions →

F

Filtration: Aluminum sheets that remove low-energy photons. Required minimum total: 2.5 mm Al equivalent above 70 kVp. See Image Acquisition → Practice questions →
Focal Spot: The area on the anode where the electron beam strikes. Smaller focal spot = sharper image but lower thermal capacity. See Recorded Detail and Image Foundations → Practice questions →
Focal Spot Tolerance: Tolerance: ±50% of stated size. A 1.0 mm focal spot can measure 0.5–1.5 mm and still pass QC. See Radiography Quality Control → Practice questions →
Focusing Cup: Negative-charged cup around the filament that focuses the electron beam onto the target. See X-Ray Tube and Equipment for ARRT → Practice questions →
Fomite: An inanimate object that carries infectious organisms (a cassette, a marker, a cell phone). Disinfect between patients. See Infection Control for ARRT Radiographers → Practice questions →
Foreshortening: Shape distortion from the part being at an angle to the IR. Projects shorter than reality. See Image Quality and Technical Factors → Practice questions →
Frontal Sinus: Air-filled cavity in the frontal bone above the orbits. Best demonstrated on the Caldwell. See Paranasal Sinus Radiography → Practice questions →

G

Gastrografin (Water-Soluble Iodinated Contrast): Substitute for barium when GI perforation is suspected. Safer because it is absorbable from the peritoneum. See GI and Hepatobiliary Procedures → Practice questions →
Grashey Method: AP oblique shoulder with 35–45° body rotation toward the affected side. Demonstrates the glenohumeral joint space in profile. See Upper Extremity Positioning → Practice questions →
Gray (Gy): SI unit of absorbed dose. 1 Gy = 100 rad. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
Greenstick Fracture: Incomplete fracture seen in pediatric bones. The cortex bends and breaks on one side only. See Trauma Radiography for ARRT → Practice questions →
Grid Cutoff: Density loss caused by improper grid positioning (off-center, off-level, off-focus, upside down). See Pathology, Artifacts, and Processor Errors → Practice questions →
Grid Ratio: Height of lead strips ÷ distance between strips. Higher ratio = better scatter cleanup, more mAs required. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →

H

Half-Value Layer (HVL): Thickness of aluminum that reduces beam intensity by 50%. Must be ≥ 2.5 mm Al at 80 kVp. See Radiography Quality Control → Practice questions →
Heat Units (HU): Quantification of tube thermal load. HU = kVp x mA x s x generator multiplier: single-phase = 1.0, three-phase 6-pulse = 1.35, three-phase 12-pulse = 1.41, high-frequency = 1.45. See X-Ray Tube and Equipment for ARRT → Practice questions →
Heel Effect: Beam intensity is greater on the cathode side of the field. Place thicker body parts on the cathode side. See Recorded Detail and Image Foundations → Practice questions →
Hepatobiliary Imaging: Imaging of the liver, gallbladder, and biliary tree. Includes T-tube cholangiography and operative cholangiography. See GI and Hepatobiliary Procedures → Practice questions →
HIPAA: Health Insurance Portability and Accountability Act of 1996. Governs the privacy and security of all identifiable health information, electronic, paper, and oral. See Foundations of Practice → Practice questions →
Histogram: Distribution of pixel values across the image. The CR system normalizes the histogram to a target shape during processing. See Computed Radiography and Digital Workflow → Practice questions →
Holmblad Method: PA knee with 70° flexion and perpendicular central ray. Demonstrates the intercondylar fossa. See Lower Extremity Positioning → Practice questions →
Horizontal Beam: Central ray traveling parallel to the floor. Required to demonstrate air-fluid levels when the patient is erect. See Paranasal Sinus Radiography → Practice questions →

I

Image Intensifier: Fluoroscopic device that converts x-rays to visible light, accelerates electrons, and focuses onto a small output phosphor. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →
Informed Consent: Legal authorization given by a patient who is of legal age, of sound mind, acting freely, and adequately informed about the procedure and its risks. See Foundations of Practice → Practice questions →
Intensifying Screen: Phosphor screen that converts x-ray photons to visible light. Multiplies detective efficiency 30–60×. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →
Inverse Square Law: Beam intensity is inversely proportional to the square of the distance from the source. Double SID = 1/4 intensity. See Image Acquisition → Practice questions →
IVU (Intravenous Urography): Contrast study of the urinary tract. Sequential films at 1, 5, 10, 15, 20 minutes plus post-void. See GI and Hepatobiliary Procedures → Practice questions →

J

Jones Fracture: Transverse fracture at the base of the 5th metatarsal. Distinct from a styloid avulsion fracture. See Lower Extremity Positioning → Practice questions →

K

kVp: Kilovoltage peak. Controls beam quality (penetration) and contrast scale. Higher kVp = longer gray scale. See Image Acquisition → Practice questions →
kVp Accuracy: Tolerance: ±5% of the indicated value. A 100 kVp setting should produce 95–105 kVp actual. See Radiography Quality Control → Practice questions →

L

Last-Image Hold (LIH): Fluoroscopic feature that preserves the last frame on screen without continuing exposure. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
Lateral Decubitus: Patient lying on their side with a horizontal central ray. Used to demonstrate air-fluid levels and free air. See Positioning Foundations → Practice questions →
Lead Apron: Minimum 0.25 mm Pb equivalent. 0.5 mm preferred for fluoroscopy. Inspect every six months. See Radiation Protection for ARRT → Practice questions →
Lead Marker Rule: R or L lead marker must be visible inside the collimated field, anatomically correct, before exposure. See Image Evaluation and Grid Artifacts → Practice questions →
Left Lateral Decubitus: Patient lies on the left side, horizontal CR. Demonstrates free fluid on the left or free air on the right. See Chest X-Ray for ARRT → Practice questions →
Line Focus Principle: The angled anode produces a small effective focal spot from a larger actual focal spot. Allows high tube loading with good resolution. See Recorded Detail and Image Foundations → Practice questions →
Lordotic Position: Patient leans back so the central ray is angled relative to the body. Demonstrates apices and middle lobe free of clavicles. See Chest X-Ray for ARRT → Practice questions →

M

Magnification Factor: SID / SOD. Larger MF = more magnification. Minimized by maximizing SID and minimizing OID. See Recorded Detail and Image Foundations → Practice questions →
mAs: Milliampere-seconds. Controls beam quantity (number of photons) and is directly proportional to density. See Image Acquisition → Practice questions →
Maxillary Sinus: Largest paranasal sinus, located in the maxilla below the orbit. Best demonstrated on the Waters. See Paranasal Sinus Radiography → Practice questions →
Mild Contrast Reaction: Warmth, metallic taste, mild urticaria, transient nausea. Requires observation only, no medication needed. See Emergencies → Practice questions →
Moiré Pattern: Interference pattern from interaction of grid lines with the digital sampling matrix. CR/DR artifact. See Computed Radiography and Digital Workflow → Practice questions →
Motion Artifact: Blurred edges from patient or equipment motion during exposure. Reduced by short exposure time and immobilization. See Pathology, Artifacts, and Processor Errors → Practice questions →
Motion Blur: Image unsharpness from patient movement during exposure. Minimized by short exposure time and immobilization. See Recorded Detail and Image Foundations → Practice questions →
Myelography: Contrast study of the spinal subarachnoid space. Lumbar puncture below L3, water-soluble iodinated contrast. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →

N

Nasal Cannula: Low-flow oxygen delivery: 24–44% FiO2 at 1–6 L/min. The most common O2 device. See Emergencies → Practice questions →
Negligence: Failure to exercise the care a reasonably prudent radiographer would in similar circumstances. Requires duty, breach, injury, and cause. See Foundations of Practice → Practice questions →
Non-Rebreather Mask: High-flow oxygen mask with reservoir: 60–95% FiO2 at 10–15 L/min. Used in respiratory distress. See Emergencies → Practice questions →

O

Occupational Dose Limit: NCRP-recommended 5 rem (50 mSv) per year whole body. Lifetime: 1 rem × age. See Radiation Protection for ARRT → Practice questions →
Off-Center Grid Cutoff: Grid error where the central ray is not aligned with the grid centerline. Entire image is uniformly light. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →
Off-Focus Grid Cutoff: Lateral edges dark. Caused by SID outside the grid's specified focal range. See Image Evaluation and Grid Artifacts → Practice questions →
Off-Level Grid Cutoff: Grid error where the IR is tilted relative to the central ray. One side of the image is darker than the other. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →
OML (Orbitomeatal Line): Cranial baseline from the outer canthus of the eye to the external acoustic meatus. Reference for most skull positioning. See Skull, Face, and TMJ Positioning → Practice questions →
Open-Mouth Odontoid: AP cervical projection with the mouth open. Demonstrates C1, C2, and the dens between the upper teeth and skull base. See Spine and Bony Thorax Positioning → Practice questions →

P

PA Chest: Posteroanterior chest projection. 72-inch SID, patient erect, scapulae cleared, full inspiration. The standard adult chest. See Chest X-Ray for ARRT → Practice questions →
Penumbra: Geometric unsharpness at the edge of an image due to the finite size of the focal spot. See Recorded Detail and Image Foundations → Practice questions →
Personal Dosimeter: TLD or OSL badge worn at collar level, outside the apron during fluoroscopy. Records cumulative occupational dose. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
Photoelectric Effect: Photon transfers all energy to a K-shell electron and is absorbed. Produces diagnostic contrast, bone vs. soft tissue. See Radiation Physics and Radiobiology for ARRT → Practice questions →
Photostimulable Phosphor (PSP): Barium fluorohalide doped with europium. Traps electrons proportional to x-ray exposure. Read by laser scanner. See Computed Radiography and Digital Workflow → Practice questions →
Pi Lines: Repeating density variations from worn or sticky processor rollers. A film-screen processor artifact. See Pathology, Artifacts, and Processor Errors → Practice questions →
Pneumothorax: Air in the pleural space. Best seen on upright expiratory PA or lateral decubitus with the affected side up. See Chest X-Ray for ARRT → Practice questions →
Position: How the body is placed on the table (supine, prone, recumbent, erect, decubitus). Distinct from projection. See Positioning Foundations → Practice questions →
Pott Fracture: Bimalleolar ankle fracture from forced eversion. Both medial and lateral malleoli are involved. See Lower Extremity Positioning → Practice questions →
Potter-Bucky Diaphragm: Oscillating grid that blurs lead strips during exposure. Makes the grid invisible on the final image. See Density, Contrast, Screens, and Grids for ARRT → Practice questions →
Pregnant Radiographer Dosimetry: Second badge worn at waist level under the lead apron. Monitors embryo dose separately. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
Pregnant Radiographer Limit: 0.5 rem (5 mSv) total over the gestation, 0.05 rem (0.5 mSv) per month maximum. See Radiation Protection for ARRT → Practice questions →
Projection: Path of the central ray through the body (AP, PA, lateral, oblique). Distinct from position. See Positioning Foundations → Practice questions →
Public Dose Limit: NCRP-recommended 0.1 rem (1 mSv) per year for the general public. See Radiation Protection for ARRT → Practice questions →
Pulsed Fluoroscopy: Intermittent rather than continuous beam. Reduces dose 50–80% vs. continuous fluoroscopy. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
Pyelography: Imaging of the renal collecting system. Retrograde (catheter) or antegrade (percutaneous) approaches available. See GI and Hepatobiliary Procedures → Practice questions →

Q

Quantum Mottle: Grainy, noisy image from too few photons reaching the IR. Caused primarily by insufficient mAs (low photon fluence), often when a high-kVp / low-mAs technique is used. See Pathology, Artifacts, and Processor Errors → Practice questions →

R

RAO 40–70° UGI: Right anterior oblique 40–70° rotation during an upper GI series. Demonstrates the duodenal bulb in profile. See GI and Hepatobiliary Procedures → Practice questions →
RAO Sternum: Right anterior oblique 15–20° rotation. Throws the sternum off the spine and against the heart shadow. See Spine and Bony Thorax Positioning → Practice questions →
Reciprocity Test: Verifies that exposures of equal mAs (different mA × time combinations) produce equal density. See Radiography Quality Control → Practice questions →
Recorded Detail: Sharpness of imaged structures. Improved by a small focal spot, minimal motion, small OID, long SID, and good screen-film contact. See Image Quality and Technical Factors → Practice questions →
Rectification: Conversion of AC to DC. Half-wave (one diode), full-wave (four diodes), three-phase, high-frequency. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →
Repeat Exposure Rate (REE): Department QC metric. Ideal <5%; >8% triggers root cause analysis. See Image Evaluation and Grid Artifacts → Practice questions →
Ripple: Variation in voltage during the AC cycle. Single-phase: 100%; three-phase six-pulse: 13%; high-frequency: <1%. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →

S

Sagittal Plane: Vertical plane that divides the body into left and right portions. Midsagittal divides into equal halves. See Positioning Foundations → Practice questions →
Salter-Harris Fracture: Pediatric fracture involving the epiphyseal plate. Classified Types I–V by the Salter-Harris system. See Trauma Radiography for ARRT → Practice questions →
Scaphoid Fracture: Most commonly fractured carpal bone. High risk of avascular necrosis. Often missed on routine PA, use the Stecher. See Upper Extremity Positioning → Practice questions →
Schueller Method: Axiolateral TMJ projection with CR 25–30° caudad. Used for closed and open mouth comparison. See Skull, Face, and TMJ Positioning → Practice questions →
Scotty Dog: Anatomic pattern on a 45° lumbar oblique where the pars interarticularis is the dog's neck. A 'collar' indicates spondylolysis. See Spine and Bony Thorax Positioning → Practice questions →
Sensitometry: Daily processor QC. A controlled film exposure measured for base+fog, mid-density, and contrast. See Radiography Quality Control → Practice questions →
Settegast Method: Sunrise/skyline projection of the patellofemoral joint with the knee flexed and beam tangential to the patella. See Lower Extremity Positioning → Practice questions →
Sievert (Sv): SI unit of equivalent or effective dose. 1 Sv = 100 rem. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
Six-Foot Rule: Minimum distance from patient during portable radiography. Stand perpendicular to the beam. See Personal Dosimetry and Fluoroscopy Protection for the ARRT → Practice questions →
SMV (Submentovertical): Skull base projection. IOML parallel to IR, CR perpendicular. Demonstrates sphenoid sinuses and skull base. See Skull, Face, and TMJ Positioning → Practice questions →
Spatial Resolution: The ability to distinguish small adjacent objects. Measured in line pairs per millimeter (lp/mm). See Recorded Detail and Image Foundations → Practice questions →
Sphygmomanometer: Blood pressure cuff. Wrap around the upper arm, listen for Korotkoff sounds with the stethoscope. See Patient Communication and Care for ARRT → Practice questions →
Spondylolysis: Defect in the pars interarticularis. Visible as a 'collar' on the Scotty Dog (lumbar oblique). See Spine and Bony Thorax Positioning → Practice questions →
Stand-Pivot Transfer: Transfer technique for ambulatory patients who can bear weight. Stand on the patient's weak side, pivot toward the destination. See Patient Communication and Care for ARRT → Practice questions →
Standard Precautions: Treat every patient's blood, body fluids, secretions, and non-intact skin as potentially infectious. Applies to every patient, every time. See Infection Control for ARRT Radiographers → Practice questions →
Stecher Method: PA wrist projection with ulnar deviation and 20° proximal central-ray angle. Elongates the scaphoid to reveal fractures. See Upper Extremity Positioning → Practice questions →
Stenvers Method: PA petrous bone projection with 45° head rotation. Demonstrates the petrous portion in profile. See Skull, Face, and TMJ Positioning → Practice questions →
Step-Up Transformer: Transformer with more secondary turns than primary turns. Steps voltage up to kVp range. See X-Ray Circuit and Fluoroscopy for ARRT → Practice questions →
Sterile Technique: Asepsis maintained for invasive procedures. The sterile field extends 1 inch from any edge, touch outside that and the field is contaminated. See Infection Control for ARRT Radiographers → Practice questions →
Stochastic Effect: Probabilistic effect (cancer, genetic mutation). No threshold; probability increases with dose. See Radiation Physics and Radiobiology for ARRT → Practice questions →

T

Thermionic Emission: Boiling of electrons from a heated filament. The first step in x-ray production. See X-Ray Tube and Equipment for ARRT → Practice questions →
Time, Distance, Shielding: The three cardinal rules of radiation protection. Apply all three to minimize occupational and patient dose. See Radiation Protection for ARRT → Practice questions →
Timer Accuracy: Tolerance: ±5% of the indicated time. Tested with a spinning-top test or motorized timer. See Radiography Quality Control → Practice questions →
Tort: A civil wrong (not criminal) for which the injured party may seek damages. Radiography practice deals almost exclusively with civil law. See Foundations of Practice → Practice questions →
Towne Method: AP axial skull with CR 30° caudad to OML. Demonstrates occipital bone and dorsum sellae within foramen magnum. See Skull, Face, and TMJ Positioning → Practice questions →
Transverse Plane: Horizontal plane that divides the body into superior and inferior portions. Also called the axial or horizontal plane. See Positioning Foundations → Practice questions →
Trendelenburg Position: Patient supine with feet elevated 15–30°. Used for shock and hypotension to increase venous return. See Emergencies → Practice questions →
Two-Factor Identification: Confirming patient identity using two independent identifiers (name + DOB) before every procedure. The Joint Commission standard. See Patient Communication and Care for ARRT → Practice questions →

U

Upside-Down Grid: Center properly exposed, both edges dark and worsening peripherally. Always verify grid orientation arrows. See Image Evaluation and Grid Artifacts → Practice questions →

V

Vasovagal Syncope: Brief loss of consciousness from sudden parasympathetic outflow. Often triggered by pain, anxiety, or seeing blood. See Emergencies → Practice questions →
Venography: Contrast imaging of veins. Largely replaced by Doppler ultrasound for DVT diagnosis. See Myelography, Cardiac Cath, Angiography, Venography for the ARRT → Practice questions →
Vital Signs: Pulse, respiration, blood pressure, temperature, and oxygen saturation. Adult normals: 60–100, 12–20, <120/80, 98.6°F, 95–100%. See Patient Communication and Care for ARRT → Practice questions →

W

Waters Method: Parietoacanthial projection. OML 37° to IR, CR perpendicular. Demonstrates maxillary sinuses. See Skull, Face, and TMJ Positioning → Practice questions →
Waters Sinus: Parietoacanthial projection. OML 37° to the IR. Demonstrates the maxillary sinuses without petrous ridge superimposition. See Paranasal Sinus Radiography → Practice questions →
Window Level: Center pixel value of the displayed window. High level = darker overall image. See Computed Radiography and Digital Workflow → Practice questions →
Window Width: Range of pixel values displayed as gray scale. Wide width = low contrast, long scale of grays. See Computed Radiography and Digital Workflow → Practice questions →

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About this glossary

How many terms are tested on the ARRT Radiography Boards?

The ARRT Radiography Content Specifications include roughly 250–300 distinct technical terms across patient care, image production, procedures, and safety. Our glossary covers the 185 highest-yield terms, the ones that have appeared on past administrations of the registry and that anchor the conceptual content in the 2025 Content Specifications.

Should I memorize all the radiography terminology?

You don't need to memorize every term verbatim. You need to understand each one well enough to recognize it in a question stem and in the rationale. The most-tested categories of terms are: positioning vocabulary (projection, position, angulation), fracture types (Colles, Boxer, Salter-Harris), legal terms (tort, negligence, four conditions of consent), photon interactions (photoelectric, Compton), and dose units (Gy, Sv, rad, rem). Master those families first.

How is this glossary organized?

Alphabetically A through Z, with cross-references to the chapter where each term is taught in depth. 185 unique terms across all 27 chapters of the curriculum. Use Cmd-F or Ctrl-F to search the page for any term you encounter in a practice question.