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RADT456 Equip Op/QC

ARRT registry review covering Equipment Operation and Q.C. content area

QuestionAnswer
Type of x-ray production when a high speed electron passes near or through a tungsten atom, and the electron is attracted to positively charged nucleus, which causes the electron to brake/slow down and be deflected from its course with a loss of energy. Bremsstrahlung radiation (Pg. 431)
Comprises 70-90% of the x-ray beam. Bremsstrahlung radiation (Pg. 431)
Type of x-ray production that occurs when a high-speed electron encounters a tungsten atom within the anode and ejects a "K" shell electron. At this point, an electron from the "L" shell moves to fill the void. Characteristic radiation (Pg. 431)
Comprises 10-30% of the x-ray beam. Characteristic radiation (Pg. 431)
True or false: all electromagnetic radiations have the same velocity (186,000 miles per second or 3 x 10^8 m/s), but differ in wavelength. True (Pg. 432)
Number of cycles per second and is measured in hertz (Hz). Frequency (Pg. 432)
Distance between two consecutive wave crests. Wavelength (Pg. 432)
True or false: Higher energy radiations have shorter wavelength and higher frequencies. True (Pg. 432)
Radiation that is capable of rearranging atoms in materials. Ionizing radiation (Pg. 433)
Principal factor affecting beam quantity. mAs (Pg. 434)
Principal factor affecting beam quality. kV (Pg. 434)
The gradual decrease in exposure rate as radiation passes through tissues. Attentuation (Pg. 434)
Photon interaction with matter where an x-ray photon uses all its energy to eject an inner shell electron, leaving an orbital vacancy (characteristic rays are then produced by filling this void). Photoelectric effect (Pg. 434)
Photon interaction with matter where an x-ray photon ejects an outer shell electron of an atom. Compton scatter (Pg. 434)
Interaction between a photon and matter where an atom absorbs an x-ray photon, becomes excited, and emits an x-ray photon of identical wavelength in a different direction than the incident photon (NO ionization occurs). Coherent scatter (AKA: classical, unmodified, or Rayleigh scatter). (Pg. 435)
Major contributor to patient dose. Photoelectric effect (Pg. 436)
Contributes to occupational dose and responsible for fogging an image. Compton scatter (Pg. 436)
___________ function to change mechanical energy to electrical energy. Generators (Pg. 437)
___________ convert electrical energy to mechanical energy. Motors (Pg. 437)
Transformers that increase voltage are called... Step-up or high voltage transformers (Pg. 440)
True or false: Transformers and autotransformers require direct current (DC) for operation. False. Transformers and autotransformers require alternating current or AC. (Pg. 441)
Degree to which transformers increase voltage is determined by... Their turns ratio (Number of turns in the secondary/high voltage coil compared to the number of turns in the primary/low voltage coil) (Pg. 440)
Transformers design types: Open Core, Closed Core, and Shell Type (Pg. 442)
Functions to provide kilovoltage selection and operates on the principle of self-induction Autotransformer (Pg. 442)
Process that changes non-useful negative half-cycles of a waveform to a useful positive half-cycle (AC to DC). Full-Wave Rectification (Pg. 442)
Amount of ripple in single-phase rectification. 100% ripple (Pg. 442)
Amount of ripple in Three-Phase/6 pulse rectification 13% ripple (Pg. 443)
Amount of ripple in Three-Phase/12 pulse rectification 4% ripple (Pg. 443)
Material used for filament within an x-ray tube cathode Tungsten (Pg. 444)
Material used for focusing cup within an x-ray tube Molybdenum (Pg. 445)
Anode materials include... Graphite/molybdenum disk, tungsten/rhenium alloy focal track, and a copper stem (Pg. 445)
True or false: An induction motor consists of a stator and a rotor, and is used to rotate an anode. True (Pg. 445)
Stators consist of a series of electromagnets and are located _______ Outside of the glass envelope (Pg. 446)
Tungsten atomic number Z = 74 (Pg. 446)
Tungsten melting point 3,410 degrees C. (Pg. 446)
Rotation speeds of an anode 3,600 to 10,000 RPM (Pg. 447)
Phenomenon that results in diminished image density at the anode end of an image, and greater density at the cathode end of an image. Anode heel effect (Pg. 447)
Effective focal spot always being smaller than the actual focal spot is called... The Line Focus Principle (Pg. 448)
Heat Unit formula HU = mA X time X kV X Generator (Pg. 448)
Conversion factors for generators in heat unit applications. Single phase = 1 Three phase/6 pulse = 1.35 Three Phase/12 pulse = 1.41 (Pg. 451)
Part of x-ray circuit that functions to automatically adjust for any fluctuations in incoming voltage supply. Line Voltage Compensator (Pg. 452)
Part of the x-ray circuit that functions to regulate the length of the x-ray exposure. Timer (Pg. 452)
Test used to evaluate timer accuracy. Spinning-top test (Pg. 453)
Primary/Low voltage circuit components Main switch/circuit breaker, autotransformer, kV selector switch, line voltage compensator, timer, primary coil of high voltage transformer, and exposure switch. (Pg. 455)
Secondary/High voltage circuit components: Secondary coil of high voltage transformer, mA meter, rectifiers, and x-ray tube. (Pg. 456)
Amount of heat versus x-ray production when photons interact with tungsten target. 99.8% heat versus 0.2% x-rays (Pg. 456)
Two dimensional picture element Pixel (Pg. 457)
Three dimensional picture element Voxel (Pg. 457)
Digital image resolution improves with: Smaller pixel size, smaller pixel pitch, and larger image matrix (Pg. 458)
True or false: photostimulable storage phosphors (PSPs) are light sensitive. False. PSPs are not light sensitive (Pg. 459)
Artifact that can occur if the direction of lead strips and grid frequency matches the scan frequency of the reader. Aliasing artifact or Moire Artifact (Pg. 462)
True or false: If an image plate and its PSP plate has been stored, unused, for 6 hours, the PSP plate should be erased prior to use. False. It should be erased if unused for 48 hours or more (Pg. 462)
Process of changing the contrast and density setting on a digital image. Windowing (Pg. 463)
Controls the number of shades of gray in an image Window width (Pg. 463)
Corresponds to the density and brightness of an image. Window level (Pg. 463)
CR resolution is improved by smaller barium fluorohalide phosphors, narrower width laser beam, and larger monitor matrix (Pg. 463)
Electronic term for anything that interferes with visualization of an image. Noise (Pg. 463)
Terms used to describe the range of grays a digital system is capable of displaying Dynamic range or contrast resolution (Pg. 466)
Hounsfield Unit for bone 1,000 (Pg. 468)
Hounsfield unit for water 0 (Pg. 468)
Hounsfield unit for air -1,000 (Pg. 468)
Relationship between the distance the CT couch travels during one x-ray tube rotation and the width of the beam/slice. Pitch (Pg. 468)
Pitch value less than 1.0 Oversampling (Pg. 468)
Pitch values greater than 1.0 Undersampling (Pg. 468)
Four parts to a CT scanner Couch/Table, gantry, computer, and operating console with display (Pg. 474)
Typical entrance skin exposure rate for fluoroscopy exams 2 R/min (Pg. 476)
Purpose of a CCD on a fluoroscopy unit converts visible light to an electrical charge (which is sent to the analog-to-digital converter) (Pg. 476)
Tabletop fluoroscopy dose limit Must not exceed 10 R/min (Pg. 478)
Minimum distance between fluoroscopy x-ray source and tabletop At least 12 inches, preferably 15 inches (Pg. 478)
Contributing factors for patient dose during fluoroscopy exams Exposure rate, tissue thickness/density, and length of exposure (Pg. 479)
Input screen material of today's image intensifier screen Cesium iodide (Pg. 479)
The ratio of light photons at the output phosphor to the number at the input phosphor Flux gain (Pg. 480)
Formula for minification gain (Input screen diameter/Output screen diameter)^2 (Pg. 480)
Formula for total brightness gain Total brightness gain = flux gain x minification gain (Pg. 480)
Reduction of brightness, resolution, and contrast around the peripheries of a fluoroscopy image is termed: Vignetting (Pg. 481)
Parts of an image intensifier Input screen, photocathode, electrostatic focusing lenses, accelerating anode, and output screen within a vacuum glass envelope (Pg. 481)
Function of automatic brightness control on fluoroscopy units Maintains constant brightness and contrast of the output screen image by adjusting kV and/or mA for differing thicknesses of body parts (Pg. 482)
What colors (wavelengths) of visible light are panchromatic films sensitive to? All colors (wavelengths) (Pg. 483)
What colors (wavelengths) of visible light are orthochromatic films sensitive to? All colors (wavelengths) but red. (Pg. 483)
What are the three sizes of spot films in non-digital fluoroscopy? 70-mm, 90-mm, and 105-mm. (Pg. 483)
Advantages of flat panel fluoroscopy Pulsed x-ray beam, decrease in patient dose, increased sensitivity to x-rays (DQE), increased temporal resolution, decreased motion un-sharpness, improved contrast, less spatial resolution (Pg. 485)
Council that places federal regulations on equipment design, performance, and use National Council on Radiation Protection and Measurements (NRCP) (Pg. 493)
Methodical evaluation of imaging components to ensure proper functioning Quality control AKA QC (Pg. 493)
Some equipment components that are tested annually Focal spot size, linearity, reproducibility, filtration, kV, and exposure time (Pg. 494)
General diagnostic equipment kV should not vary more than _______. +/- 4 kV (Pg. 494)
Quality control tool used to evaluate mA station accuracy Aluminum step-wedge or penetrometer (Pg. 495)
mAs output (measured in mR/mAs) should be accurate to within _____. 10% (Pg. 495)
Timer accuracy should be within ______ of the actual exposure time. 5% (Pg. 495)
Term used to describe the relationship between the collimator light field and the actual x-ray field. Congruence (Pg. 496)
Relationship between the collimator light field and the actual x-ray field must be in congruence within _____ of the SID. 2% (Pg. 496)
Centering indication is require and must be to within what percentage of the central ray? 1% (Pg. 496)
How often should collimators be inspected and verified accurate? Semiannually (Pg. 496)
Reproducibility tests should register that mAs radiation output does not vary by more than _______. 5% (Pg. 496)
What is half-value layer defined as? The thickness of any absorber that will reduce the x-ray beam intensity to one-half its original value. (Pg. 496)
Quality control tools used to measure focal spot size. Pinhole camera, slit camera, or star-pattern resolution devices. (Pg. 497)
How often should slip-on/clip-on grids be evaluated. Every 6 months. (Pg. 498)
Maximum exposure rate in manual fluoroscopy should not exceed _____. 5 R/min (Pg. 498)
Maximum exposure rate for fluoroscopy exams in automatic exposure mode should not exceed _______. 10 R/min (Pg. 498)
How often should lead aprons, gloves, and thyroid shields be evaluated? Annually (Pg. 498)
Kilovoltage accuracy should should be accurate to within _____. 5 kV (+/-10%) (Pg. 500)
Created by: jksmith1