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58 Cards in this Set
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Which of the following groups of technical factors will produce the greatest radiographic density?
A. 400 mA, 0.010 second, 94 kVp, 100-speed screens B. 500 mA, 0.008 second, 94 kVp, 200-speed screens C. 200 mA, 0.040 second, 94 kVp, 50-speed screens D. 100 mA, 0.020 second, 80 kVp, 200-speed screens |
B. 500 mA, 0.008 second, 94 kVp, 200-speed screens
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EXPLANATION: Each mAs is determined (A = 4; B = 4; C = 8; D = 2) and numbered in order of greatest to least density (C = 1; A and B = 2; D = 3). Then the kilovoltages are reviewed and also numbered in order of greatest to least density (A, B, and C = 1; D = 2). Next, screen speeds are numbered from greatest-density-producing to least-density-producing (D and B = 1; A = 2; C = 3). Finally, the numbers assigned to the mAs, kVp, and screen speed are added up for each of the four groups (B = 4; A and C = 5; D = 6); the lowest total (B) indicates the group of factors that will produce the greatest radiographic density. This process is illustrated as follows:
A. 4 mAs (2) + 94 kVp (1) + 100 screens (2) = 5 B. 4 mAs (2) + 94 kVp (1) + 200 screens (1) =4 C. 8 mAs (1) + 94 kVp (1) + 50 screens (3) = 5 D. 2 mAs (3) + 80 kVp (2) + 200 screens (1) = 6 |
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Hardener is added to the developer solution of automatic processors to
1. keep emulsion swelling to a minimum. 2. decrease the possibility of a processor jam-up. 3. remove unexposed silver halide crystals. |
B. 1 and 2 only
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EXPLANATION: The distance between transport rollers in an automatic processor is extremely critical and allows for exact film thickness with minimum emulsion swelling. If the emulsion is allowed to swell excessively (as a result of excessive temperature or inadequate replenishment), the emulsion will stick to the rollers and cause a processor jam-up. Glutaraldehyde is a hardener that is added to the developer to keep the emulsion swelling to a minimum. Unexposed silver halide crystals are removed in the fixer solution. (Shephard, p 135)
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Which of the following will occur as a result of a decrease in the anode target angle?
1. Less pronounced anode heel effect 2. Decreased effective focal spot size 3. Greater photon intensity toward the cathode side of the x-ray tube |
C. 2 and 3 only
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EXPLANATION: Target angle has a pronounced geometric effect on the effective, or projected, focal spot size. As the target angle decreases, the effective (projected) focal spot becomes smaller. This is advantageous because it will improve radiographic detail without creating a heat-loading crisis at the anode (as would occur if the actual focal spot size were reduced to produce a similar detail improvement). There are disadvantages, however. With a smaller target angle, the anode heel effect increases; photons are more noticeably absorbed by the "heel" of the anode, resulting in a smaller percentage of x-ray photons at the anode end of the x-ray beam and a concentration of x-ray photons at the cathode end of the radiograph.
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How will x-ray photon intensity be affected if the SID is doubled?
A. Its intensity increases two times. B. Its intensity increases four times. C. Its intensity decreases two times. D. Its intensity decreases four times. |
D. Its intensity decreases four times.
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EXPLANATION: Source-to-image-receptor distance (SID) has a significant impact on x-ray beam intensity (other terms we could use are exposure rate and dose). As the distance between the x-ray tube and image receptor increases, exposure rate/intensity/dose (and therefore radiographic density) decreases according to the inverse square law. According to the inverse square law, the exposure rate is inversely proportional to the square of the distance; that is, if the SID is doubled, the resulting beam intensity will be one fourth the original intensity; if the SID is cut in half, the resulting beam intensity will be four times the original intensity.
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The term effective dose refers to
A. whole-body dose. B. localized organ dose. C. genetic effects. D. somatic and genetic effects. |
A. whole-body dose.
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EXPLANATION: Every radiographic examination involves an ESE, which can be determined fairly easily. It also involves a gonadal dose and marrow dose, which if needed, can be calculated by the radiation physicist. If the ESE of a particular examination was calculated to determine the equivalent whole-body dose, this is termed the effective dose. For example, the ESE of a PA chest is approximately 70 mrem, while the effective dose is 10 mrem. The effective (whole-body) dose is much less because much of the body is not included in the primary beam.
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The automatic exposure device that is located immediately under the x-ray table is the
A. ionization chamber. B. scintillation camera C. photomultiplier. D. photocathode. |
A. ionization chamber
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EXPLANATION: Automatic exposure control (AEC) devices are used in today's equipment and serve to produce consistent and comparable radiographic results. In one type of AEC, there is an ionization chamber just beneath the tabletop above the cassette. The part to be examined is centered on it (the sensor) and radiographed. When a predetermined quantity of ionization has occurred (equal to the correct density), the exposure terminates automatically. In the other type of AEC, the phototimer/photomultiplier, a small fluorescent screen is positioned beneath the cassette. When remnant radiation emerging from the patient exposes the IR and exits the cassette, the fluorescent screen emits light. Once a predetermined amount of fluorescent light is "seen" by the photocell sensor, the exposure is terminated. A scintillation camera is used in nuclear medicine. A photocathode is an integral part of the image intensification system.
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The fact that x-ray intensity across the primary beam can vary as much as 45% describes the
A. line focus principle B. transformer law. C. anode heel effect. D. inverse square law. |
C. anode heel effect
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EXPLANATION: A beveled focal track extends around the periphery of the anode disc; when a small angle is used, the beveled edge allows for a smaller effective focal spot and better detail. The disadvantage, however, is that photons are noticeably absorbed by the "heel" of the anode, resulting in a smaller percentage of x-ray photons at the anode end of the x-ray beam and a concentration of x-ray photons at the cathode end of the beam. This is known as the anode heel effect and can cause a primary beam variation of up to 45%. The anode heel effect becomes more pronounced as the SID decreases, as IR size increases, and as target angle decreases.
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The left sacroiliac joint is positioned perpendicular to the IR when the patient is positioned in a
A. left lateral position. B. 25° to 30° LAO position. C. 25° to 30° LPO position. D. 30° to 40° LPO position. |
B. 25° to 30° LAO position
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EXPLANATION: Sacroiliac joints lie obliquely within the pelvis and open anteriorly at an angle of 25° to 30° to the midsagittal plane. A 25° to 30° oblique position places the joints perpendicular to the IR. The left sacroiliac joint may be demonstrated in the LAO and RPO positions with little magnification variation.
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An aspirated foreign body is more likely to enter the lower respiratory tract via the
A. left main stem bronchus. B. right main stem bronchus. C. bronchioles. D. alveoli. |
B. right main stem bronchus
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EXPLANATION: The right and left main stem (primary) bronchi branch from the distal trachea; the right branch supplies air to the right lung, and the left branch supplies air to the left lung. The right main stem bronchus is shorter, wider, and more vertical than the left—making it the most likely route for aspirated foreign bodies to enter the right lung.
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Irradiation of macromolecules in vitro can result in
1. main chain scission. 2. cross-linking. 3. point lesions. A. 1 only B. 1 and 2 only C. 2 and 3 only D. 1, 2, and 3 |
D. 1, 2, and 3
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EXPLANATION: Irradiation damage is a result of either the effects of irradiation on water (radiolysis) or its effects on macromolecules. Effects on macromolecules include main chain scission, cross-linking, and point lesions. Main chain scission breaks the DNA molecule into two or more pieces. Cross-linking is incorrect joining of broken DNA fragments. A point lesion is the disruption of a single chemical bond as a result of irradiation. Because 80% of the body is made up of water, radiolysis of water is the predominant radiation interaction in the body.
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Which of the following terms refers to light being reflected from one intensifying screen, through the film, to the opposite emulsion and screen?
A. Reflectance B. Crossover C. Scatter D. Filtration |
B. Crossover
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EXPLANATION: If fluorescent light from one intensifying screen passes through the film to the opposite emulsion and intensifying screen, the associated diffusion creates a type of distortion called crossover. Intensifying screens do need a degree of reflectance to enhance their speed. Scatter and filtration are unrelated to intensifying screens.
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The line focus principle refers to the fact that
A. the actual focal spot is larger than the effective focal spot. B. the effective focal spot is larger than the actual focal spot. C. x-rays travel in straight lines. D. x-rays cannot be focused. |
A. the actual focal spot is larger than the effective focal spot.
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EXPLANATION: A distinction is made between the actual focal spot and the effective, or projected, focal spot. The actual focal spot is the finite area on the tungsten target that is actually bombarded by electrons from the filament. The effective focal spot is the foreshortened size of the focus as it is projected down toward the image receptor. This is called line focusing or the line focus principle. The quoted focal spot size is the effective focal spot size.
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What should be done to better demonstrate the mandibular rami.
A. use a perpendicular CR B. angle the CR cephalad C. angle the CR caudad D. oblique the head 15° medial |
B. angle the CR cephalad
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EXPLANATION: Figure A shows a PA projection of the mandible. The head is positioned PA with the OML perpendicular to the IR. The mandibular body is well demonstrated in this position. With the patient in the PA position, the rami can be better demonstrated with 20° to 25° cephalad angulation. A caudal angle could be employed if the skull was positioned in the AP position.
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If the anode is saturated with 300,000 heat units (HU), how long will the anode need to cool before another 160,000 heat units can be safely applied?
A. 3 minutes B. 4 minutes C. 5 minutes D. 7 minutes |
B. 4 minutes
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EXPLANATION: Each x-ray exposure made by the radiographer produces hundreds or thousands of heat units at the target. If the examination requires several consecutive exposures, the potential for extreme heat load is increased. Just as each x-ray tube has its own radiographic rating chart, each tube also has its own anode cooling curve to describe its unique heating and cooling characteristics. An x-ray tube generally cools most rapidly during the first 2 minutes of nonuse. First, note that the tube is saturated with heat at 300,000 HU. In order for another 160,000 HU to be safely applied, the x-ray tube must first release 160,000 HU, which means that it has to cool down at least to 140,000 HU. Find the 140,000 point on the vertical axis and follow across to where it intersects with the cooling curve. It intersects at about the 4-minute point.
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An RT (ARRT) is supervising manager of a short-staffed imaging facility in a state requiring certification. An applicant arrives whose ARRT certification has lapsed. The manager hires him to fill a 20-hour position doing chest and extremity radiography. The supervisor is guilty of
A. breaking the ARRT Code of Ethics. B. breaking the ARRT Rules of Ethics. C. malpractice. D. nothing, because position responsibilities are limited. |
B. breaking the ARRT Rules of Ethics.
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EXPLANATION: The ARRT Standards of Ethics apply to those Registered Technologists holding ARRT certification and Candidates for ARRT certification. The Standards consist of two parts: the Code of Ethics (aspirational) and the Rules of Ethics (mandatory). The ARRT Rules of Ethics are mandatory minimum professional standards for all RTs and candidate RTs. Violators, and individuals who permit violation, of these Rules are subject to sanctions. Rules of Ethics numbers 15 and 21 specifically refer to those who knowingly assist another without proper certification to engage in the practice of radiologic technology, and/or those who fail to promptly report such activity to the ARRT—as being subject to sanction.
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.All of the following statements regarding three-phase current are true except
A. Three-phase current is constant-potential direct current. B. Three-phase equipment produces more x-rays per mAs. C. Three-phase produces higher-average-energy x-rays than single-phase. D. The three-phase waveform has less ripple than the single-phase. |
A. Three-phase current is constant-potential direct current.
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EXPLANATION: Three-phase current is obtained from three individual alternating currents superimposed on, but out of step with, one another by 120°. The result is an almost constant potential current, with only a very small voltage ripple (4% to 13%), producing more x-rays per mAs.
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Which of the following will occur as a result of a decrease in the anode target angle?
1. Less pronounced anode heel effect 2. Decreased effective focal spot size 3. Greater photon intensity toward the cathode side of the x-ray tube A. 1 only B. 1 and 2 only C. 2 and 3 only D. 1, 2, and 3 |
C. 2 and 3 only
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EXPLANATION: Target angle has a pronounced geometric effect on the effective, or projected, focal spot size. As the target angle decreases, the effective (projected) focal spot becomes smaller. This is advantageous because it will improve radiographic detail without creating a heat-loading crisis at the anode (as would occur if the actual focal spot size were reduced to produce a similar detail improvement). There are disadvantages, however. With a smaller target angle, the anode heel effect increases; photons are more noticeably absorbed by the "heel" of the anode, resulting in a smaller percentage of x-ray photons at the anode end of the x-ray beam and a concentration of x-ray photons at the cathode end of the radiograph.
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Which of the following combinations would pose the most hazard to a particular anode?
A. 0.6 mm focal spot, 75 kVp, 30 mAs B. 0.6 mm focal spot, 85 kVp, 15 mAs C. 1.2 mm focal spot, 75 kVp, 30 mAs D. 1.2 mm focal spot, 85 kVp, 15 mAs |
A. 0.6 mm focal spot, 75 kVp, 30 mAs
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EXPLANATION: Radiographic rating charts enable the operator to determine the maximum safe mA, exposure time, and kVp for a particular exposure using a particular x-ray tube. An exposure that can be made safely with the large focal spot may not be safe for use with the small focal spot of the same x-ray tube. The total number of HU that an exposure generates also influences the amount of stress (in the form of heat) imparted to the anode. The product of mAs and kVp determines HU. Groups A and C produce 2250 HU; groups B and D produce 1275 HU. Groups B and D deliver less heat load, but group D delivers it to a larger area (actual focal spot) making this the least hazardous group of technical factors. The most hazardous group of technical factors is group
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Following structures into order (A–D) from medial to lateral.
A. Coracoid process B. Scapular notch C. Acromion process D. Vertebral border |
The answer is D:B:A:C.
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EXPLANATION: (A) Vertebral border(B) Scapular notch(C) Coracoid process (D) Acromion process The scapula is a flat bone, shaped like an inverted triangle, with a costal surface that lies against the upper posterior rib cage. The scapula has a superior border, a medial (or vertebral) border, a lateral (or axillary) border, and an inferior angle, or apex. Its superior border presents a scapular notch projecting anteriorly just medial to the palpable coracoid process. The scapular spine divides the posterior surface into a supraspinatus fossa and infraspinatus fossa; the acromion process is the lateral extension of the scapular spine. The glenoid fossa is on the lateral aspect of the scapula and, with its articulation with the humeral head, forms the (ball and socket) shoulder joint.
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An emetic is used to
A. induce vomiting. B. stimulate defecation. C. promote elimination of urine. D. inhibit coughing. |
A. induce vomiting
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EXPLANATION: Emetics, such as ipecac, function to induce vomiting. Cathartics are used to stimulate defecation (bowel movements). Diuretics are used to promote urine elimination in individuals whose tissues are retaining excessive fluid, and antitussives are used to inhibit coughing.
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Disadvantages of moving grids over stationary grids include which of the following?
1. They can prohibit the use of very short exposure times. 2. They increase patient radiation dose. 3. They can cause phantom images when anatomic parts parallel their motion. A. 1 only B. 1 and 2 only C. 2 and 3 only D. 1, 2, and 3 |
B. 1 and 2 only
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EXPLANATION: One generally thinks in terms of moving grids being totally superior to stationary grids because moving grids function to blur the images of the lead strips on the radiographic image. Moving grids do, however, have several disadvantages. First, their complex mechanism is expensive and subject to malfunction. Second, today's sophisticated x-ray equipment makes possible the use of extremely short exposures, a valuable feature whenever motion may be a problem (as in pediatric radiography). However, grid mechanisms frequently are not able to oscillate rapidly enough for the short exposure times, and as a result the grid motion is "stopped" and the lead strips are imaged. Third, patient dose is increased with moving grids. Since the central ray is not always centered to the grid because it is in motion, lateral decentering occurs (resulting in diminished density), and consequently an increase in exposure is needed to compensate (either manually or via AEC).
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During a double-contrast BE, which of the following positions would afford the best double-contrast visualization of both colic flexures?
A. LAO and RPO B. Lateral C. Left lateral decubitus D. AP or PA erect |
D. AP or PA erect
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With the patient in the erect position, barium moves inferiorly and air rises to provide double-contrast visualization of the hepatic and splenic flexures. The LAO and RPO positions are used to demonstrate especially the splenic/left colic flexure; the hepatic flexure generally appears self-superimposed in this position. A left lateral decubitus position will demonstrate a double-contrast visualization of right-sided bowel structures—that is, the right side of the ascending colon, the right side of the sigmoid and rectum, and so on. The lateral position offers a singularly valuable view of the rectum.
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An automatic exposure control device can operate on which of the following principles?
1. A photomultiplier tube charged by a fluorescent screen 2. A parallel-plate ionization chamber charged by x-ray photons 3. Motion of magnetic fields inducing current in a conductor |
C. 1 and 2 only
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A phototimer is one type of automatic exposure control (AEC) that actually measures light. As x-ray photons penetrate and emerge from a part, a fluorescent screen beneath the cassette glows, and the fluorescent light charges a photomultiplier tube. Once a predetermined charge has been reached, the exposure automatically terminates. A parallel-plate ionization chamber is another type of AEC. A radiolucent chamber is beneath the patient (between the patient and the IR). As photons emerge from the patient, they enter the chamber and ionize the air within it. Once a predetermined charge has been reached, the exposure is automatically terminated. Motion of magnetic fields inducing a current in a conductor refers to the principle of mutual induction.
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Which of the following conditions is often the result of ureteral obstruction or stricture?
A. Pyelonephrosis B. Nephroptosis C. Hydronephrosis D. Cystourethritis |
C. Hydronephrosis
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Hydronephrosis is a collection of urine in the renal pelvis due to obstructed outflow, as from a stricture or obstruction. If the obstruction occurs at the level of the bladder or along the course of the ureter, it will be accompanied by the condition of hydroureter above the level of obstruction. These conditions may be demonstrated during IV urography. The term pyelonephrosis refers to some condition of the renal pelvis. Nephroptosis refers to drooping or downward displacement of the kidneys. This may be demonstrated using the erect position during IV urography. Cystourethritis is inflammation of the bladder and urethra.
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Which of the following groups of exposure factors will produce the greatest radiographic density?
A. 100 mA, 0.30 second B. 200 mA, 0.10 second C. 400 mA, 0.03 second D. 600 mA, 0.03 second |
A. 100 mA, 0.30 second
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The mAs is the exposure factor governing radiographic density. Using the equation milliamperage x time = mAs, determine each mAs: A = 30 mAs; B = 20 mAs; C = 12 mAs; D = 18 mAs. Group A will produce the greatest radiographic density.
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Which of the following is (are) valid evaluation criteria for a lateral projection of the forearm?
1. The radius and the ulna should be superimposed distally. 2. The coronoid process and the radial head should be partially superimposed. 3. The humeral epicondyles should be superimposed. |
D. 1, 2, and 3
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To accurately position a lateral forearm, the elbow must form a 90° angle with the humeral epicondyles superimposed. The radius and ulna are superimposed distally. Proximally, the coronoid process and radial head are partially superimposed. Failure of the elbow to form a 90° angle, or the hand to be lateral, results in a less-than-satisfactory lateral projection of the forearm.
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The use of which of the following is (are) essential in magnification radiography?
1. High-ratio grid 2. Fractional focal spot 3. Direct exposure film |
B. 2 only
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Magnification radiography is used to enlarge details to make them more perceptible. Hairline fractures, minute blood vessels, and microcalcifications are candidates for magnification radiography. The problem of magnification unsharpness is overcome by using a fractional focal spot; larger focal spot sizes will produce excessive blurring unsharpness. Grids are usually unnecessary in magnification radiography because of the air-gap effect produced by the OID. A direct-exposure technique would not be likely to be used because of the excessive exposure required.
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A spontaneous fracture most likely would be associated with
A. pathology.B. crepitus.C. trauma.D. metabolism. |
A. pathology.
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Spontaneous fractures most often affect bone weakened by a pathologic condition, for example, metastatic bone disease. The spontaneous fracture occurs suddenly, without trauma. One measure of a good radiographer is his or her ability to be cautious and resourceful when examining injured or debilitated patients having pathologic or traumatic conditions such as metastatic bone disease, arthritis, or bone fractures. Crepitus refers to a crackling sound made by a body part—such as the sound of fractured ends of bones rubbing together. Metabolism refers to the numerous energy and material transformations that take place in the body and is not associated with spontaneous fractures.
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Screen–film imaging is one example of a (n)
A. analog system B. digital system. C. electromagnetic system. D. direct-action radiation system |
A. analog system
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Screen–film imaging consists of an exposure method of converting x-ray energy to light energy, then converting light energy to electrochemical energy in the development process. Processing changes the invisible electrochemical image to a visible/manifest radiographic image. This process ends with analog data. Digital imaging is an electronic imaging method that allows data capture and manipulation in an electron pattern. The resulting image can be turned into an analog image after going through several energy changes (electron to light to film or TV screen). The direct action of x-rays has very little influence on a radiographic image produced with intensifying screens (fluorescent light is responsible for the majority of film exposure).
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Materials that emit light when stimulated by x-ray photons are called
A. ions. B. electrodes. C. phosphors. D. crystals. |
C. phosphors
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Materials that emit light when stimulated by x-ray photons are called phosphors. Phosphors are used in intensifying screens, where they function to absorb x-ray photon energy and convert it to visible light energy. Typically, for each x-ray photon absorbed, many light photons are emitted; intensifying screens serve to amplify the action of x-rays.
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Moderate hypertension can produce damage to which of the following organs?
1. Lungs 2. Kidneys 3. Brain A. 1 only B. 1 and 2 only C. 2 and 3 only D. 1, 2, and 3 |
D. 1, 2, and 3
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Normal blood pressure is 110–140 mmHg systolic and 60–80 mmHg diastolic. High blood pressure (hypertension) is indicated by a systolic pressure higher than 140 mmHg and a diastolic pressure higher than 90 mmHg. Hypertension can be identified as extreme or moderate. Extreme hypertension can result in brain damage within just a few minutes. Moderate hypertension can cause damage to organs—the lungs, kidneys, brain, heart, etc. Various disease processes can produce hypertension as well as contributing factors such as medications, obesity, smoking, and stress.
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Which of the following may be used to evaluate the glenohumeral joint?
1. Scapular Y projection 2. Inferosuperior axial 3. Transthoracic lateral A. 1 only B. 1 and 2 only C. 2 and 3 only D. 1, 2, and 3 |
D. 1, 2, and 3
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The scapular Y projection is an oblique projection of the shoulder and is used to demonstrate anterior or posterior shoulder dislocation. The inferosuperior axial projection may be used to evaluate the glenohumeral joint when the patient is able to abduct the arm. The transthoracic lateral projection is used to evaluate the glenohumeral joint and upper humerus when the patient is unable to abduct the arm.
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Which of the following criteria is (are) required for visualization of the greater tubercle in profile?
1. Epicondyles parallel to the IR 2. Arm in external rotation 3. Humerus in AP position A. 1 only B. 1 and 3 only C. 2 and 3 only D. 1, 2, and 3 |
D. 1, 2, and 3
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The greater and lesser tubercles are prominences on the proximal humerus separated by the intertubercular (bicipital) groove. The AP projection of the humerus/shoulder places the epicondyles parallel to the IR and the shoulder in external rotation, and demonstrates the greater tubercle in profile. The lateral projection of the humerus places the shoulder in extreme internal rotation with the epicondyles perpendicular to the IR and demonstrates the lesser tubercle in profile.
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Which of the following techniques is used to evaluate the dynamics of a part?
A. Fluoroscopy B. Stereoscopy C. Tomography D. Phototiming |
A. Fluoroscopy
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The dynamics, or motion, of a part must be studied during a "real-time" examination such as fluoroscopy affords. Stereoscopy is a technique used to produce a radiographic third dimension. Tomography produces sectional images of body parts by blurring superimposed structures above and below the section, or level, of interest. A phototimer is one type of AEC device.
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How is the mAs adjusted in an AEC system as the film–screen speed combination is decreased?
A. The mAs increases as film–screen speed decreases. B. Both the mAs and the kVp increase as film–screen speed decreases. C. The mAs decreases as film–screen speed decreases. D. The mAs remains unchanged as film–screen speed decreases. |
D. The mAs remains unchanged as film–screen speed decreases.
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As the speed of the film–screen system decreases, an increase in mAs is usually required to maintain radiographic density. However, when an automatic exposure control (phototimer or ionization chamber) is used, the system is programmed for the use of a particular film–screen speed. If a slower-speed screen cassette–image receptor is placed in the Bucky tray, the AEC has no way of recognizing it as different and will time the exposure for the system that it is programmed for. For example, if the system is programmed for a 400-speed film–screen combination, and if a 200-speed screen cassette–image receptor was placed in the Bucky tray, the resulting radiograph would have half the required radiographic density.
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Circuit devices that will conduct electrons in only one direction are
1. resistors. 2. valve tubes. 3. solid-state diodes. A. 1 only B. 1 and 3 only C. 2 and 3 only D. 1, 2, and 3 |
C. 2 and 3 only
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Rectifiers change AC into unidirectional current by allowing current to flow through them in only one direction. Valve tubes are vacuum rectifier tubes found in older equipment. Solid-state diodes are the types of rectifiers used in today's x-ray equipment. Rectification systems are found between the secondary coil of the high-voltage transformer and the x-ray tube. Resistors, such as rheostats or choke coils, are circuit devices used to vary voltage or current.
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Which of the dose-response curves pictured in Figure A illustrate(s) a linear threshold dose effect?
1. Curve number 1 2. Curve number 2 3. Curve number 3 |
B. 3 only
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Three dose-response (dose effect) curves are illustrated, representing the body's response to irradiation. Dose is indicated by the horizontal axis (increasing to the right); response is indicated by the vertical axis (increasing upward). Two of the curves (numbers 1 and 3) are linear, that is, a straight line. Curve 2 is not a straight line and is therefore nonlinear. Curves 2 and 3 show that a particular dose (threshold quantity) of radiation is required before any effect will occur; therefore, curve 2 is nonlinear threshold and curve 3 is linear threshold. Curve 1, however, shows that any dose of radiation (theoretically, even a single x-ray photon, ie, there is no threshold) can result in a particular biologic effect; therefore, it is linear nonthreshold.
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Which of the following is a radiologic procedure that functions to dilate a stenotic vessel?
A. Percutaneous nephrolithotomy B. Percutaneous angioplasty C. Renal arteriography D. Surgical nephrostomy |
B. Percutaneous angioplasty
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Plaque deposited on arterial walls in cases of atherosclerosis causes arterial stenosis. Percutaneous transluminal angioplasty (PTA) is a procedure that uses a balloon catheter to permanently increase the size of the arterial lumen, thus reopening the vessel and restoring blood flow. A percutaneous nephrolithotomy is a procedure performed to remove a renal calculus from a kidney or proximal ureter. Renal arteriography is the radiologic investigation of the renal arteries. Nephrostomy is the surgical formation of an artificial opening into the kidney.
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Unopened boxes of radiographic film should be stored away from radiation and
A. in the horizontal position. B. in the vertical position. C. stacked with the oldest on top. D. stacked with the newest on top. |
B. in the vertical position.
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Boxes of x-ray film, especially the larger sizes, should be stored in the vertical (upright) position. If film boxes are stacked upon one another, the sensitive emulsion can be affected by pressure from the boxes above. Pressure marks are produced and result in loss of contrast in that area of the radiographic image. When retrieving x-ray film from storage, the oldest should be used first.
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How would the introduction of a 6-inch OID affect image contrast?
A. Contrast would be increased. B. Contrast would be decreased. C. Contrast would not change. D. The scale of contrast would not change. |
A. Contrast would be increased.
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OID can affect contrast when it is used as an air gap. If a 6-inch air gap (OID) is introduced between the part and IR, much of the scattered radiation emitted from the body will not reach the IR, as seen in the figure below. The OID is thus acting as a low-ratio grid and increasing image contrast
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In which of the following projections is the talofibular joint best demonstrated?
A. AP B. Lateral oblique C. Medial oblique D. Lateral |
C. Medial oblique
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The AP projection demonstrates superimposition of the distal fibula on the talus; the joint space is not well seen. The 15° to 20° medical oblique position shows the entire mortise joint; the talofibular joint is well visualized, as well as the talotibial joint. There is considerable superimposition of the talus and fibula in the lateral and lateral oblique projections.
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All of the following procedures demonstrate renal function, except
A. IVP. B. descending urography. C. retrograde urography. D. infusion nephrotomography. |
C. retrograde urography
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Retrograde urography is not considered a functional study of the urinary system. IVP, descending urography, and infusion nephrotomography are all considered functional urinary tract studies because the contrast medium is introduced intravenously and excreted by the kidneys. Retrograde urography involves introduction of contrast medium into the kidneys via catheter, thereby demonstrating their structure, but not their function.
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Which of the following tube angle and direction combinations is correct for an axial projection of the clavicle, with the patient in the PA position?
A. 5° to 15° caudad B. 5° to 15° cephalad C. 15° to 30° cephalad D. 15° to 30° caudad |
D. 15° to 30° caudad
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When the clavicle is examined in the PA recumbent position, the central ray must be directed 15° to 30° caudad to project most of the clavicle's length above the ribs. The direction of the central ray is reversed when examining the patient in the AP position.
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Which of the following statements is/are true regarding Figure A?
1. The radiograph was made in the LAO position. 2. The central ray should enter more inferiorly. 3. The sternum is projected onto the left side of the thorax. |
C. 2 and 3 only
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The pictured radiograph is an RAO position of the sternum. The sternum is projected to the left side of the thorax, over the heart and other mediastinal structures, in the RAO position, thus promoting more uniform density. Although the upper limits of the sternum are well demonstrated in the figure, not all of the xiphoid process is seen, because the central ray was directed somewhat too superiorly. The central ray should be directed midway between the jugular (manubrial) notch and the xiphoid process.
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All of the following are palpable bony landmarks used in radiography of the pelvis except the
A. femoral neck. B. pubic symphysis. C. greater trochanter. D. iliac crest. |
A. femoral neck
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Femoral necks are nonpalpable bony landmarks. The ASIS, pubic symphysis, and greater trochanter are palpable bony landmarks used in radiography of the pelvis and for localization of the femoral necks.
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Which of the following is the approximate skin dose for 5 minutes of fluoroscopy performed at 1.5 mA?
A. 3.7 rad B. 7.5 rad C. 15 rad D. 21 rad |
C. 15 rad
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Fluoroscopic skin dose is greater than radiographic skin dose because the x-ray source is much closer to the patient. The generally accepted rule is that the skin receives 2 rad/min/mA. Therefore, 2 rad/min for 5 min equals 10 rad/mA. At 1.5 mA, the patient dose is 15 rad (2 rad/5 min/1.5 mA).
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Blood is returned to the left atrium, from the lungs, via the
A. aorta. B. superior vena cava. C. pulmonary veins. D. pulmonary artery. |
C. pulmonary veins
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Deoxygenated blood is collected by the superior and inferior vena cava and emptied into the right atrium.
Pulmonary circulation conveys deoxygenated blood from the right ventricle, through the pulmonary semilunar valve, into the pulmonary artery (the only artery that carries deoxygenated blood), and into the lungs where the blood becomes oxygenated. The oxygenated blood from the lungs is carried via the four pulmonary veins (the only veins that carry oxygenated blood) and emptied into the left atrium. |
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To eject a K shell electron from a tungsten atom, the incoming electron must have an energy of at least
A. 60 keV. B. 70 keV. C. 80 keV. D. 90 keV. |
B. 70 keV
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X-ray photons are produced in two ways as high-speed electrons interact with target tungsten atoms. First, if the high-speed electron is attracted by the nucleus of a tungsten atom and changes its course, as the electron is "braked," energy is given up in the form of an x-ray photon. This is called bremsstrahlung (braking) radiation, and it is responsible for the majority of the x-ray photons produced at the conventional tungsten target. Second, a high-speed electron having an energy of at least 70 keV may eject a tungsten K-shell electron, leaving a vacancy in the shell. An electron from the next energy level, the L shell, drops down to fill the vacancy, emitting the difference in energy as a K characteristic ray. Characteristic radiation makes up only about 15% of the primary beam.
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If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate?
A. 0.2 rad/min B. 2.0 rad/min C. 5 rad/min D. 200 rad/min |
A. 0.2 rad/min
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Two thousand mrad is equal to 2 rad. If 2 rad was delivered in 10 minutes, then the dose rate must be 0.2 rad/min:
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The advantage(s) of high kilovoltage chest radiography is (are) that
1. exposure latitude is increased. 2. it produces long-scale contrast. 3. it reduces patient dose. |
C. 2 and 3 only
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The chest is composed of tissues with widely differing densities (bone and air). In an effort to "even out" these tissue densities and better visualize pulmonary vascular markings, high kilovoltage is generally used. This produces more uniform penetration and results in a longer scale of contrast, with visualization of the pulmonary vascular markings as well as bone (which is better penetrated) and air densities. The increased kilovoltage also affords the advantage of greater exposure latitude (an error of a few kV will make little if any difference). The fact that the kilovoltage is increased means that the mAs is accordingly reduced, and thus patient dose is reduced as well. A grid is usually used whenever high kilovoltage is required.
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Which of the following is (are) classified as rare earth phosphors?
1. Lanthanum oxybromide 2. Gadolinium oxysulfide 3. Cesium iodide |
B. 1 and 2 only
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Rare earth phosphors have a greater conversion efficiency than do other phosphors. Lanthanum oxybromide is a blue-emitting rare earth phosphor, and gadolinium oxysulfide is a green-emitting rare earth phosphor. Cesium iodide is the phosphor used on the input screen of image intensifiers; it is not a rare earth phosphor.
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LET is best defined as
1. a method of expressing radiation quality. 2. a measure of the rate at which radiation energy is transferred to soft tissue. 3. absorption of polyenergetic radiation. |
B. 1 and 2 only
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When biologic material is irradiated, there are a number of modifying factors that determine what kind and how much response will occur in the material. One of these factors is LET, which expresses the rate at which particulate or photon energy is transferred to the absorber. Because different kinds of radiation have different degrees of penetration in different materials, it is also a useful way of expressing the quality of the radiation.
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Which of the following is most likely to produce a radiograph with a long scale of contrast?
A. Increased photon energy B. Increased screen speed C. Increased mAs D. Increased SID |
A. Increased photon energy
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An increase in photon energy accompanies an increase in kilovoltage. Kilovoltage regulates the penetrability of x-ray photons; it regulates their wavelength—the amount of energy with which they are associated. The higher the related energy of an x-ray beam, the greater its penetrability (kilovoltage and photon energy are directly related; kilovoltage and wavelength are inversely related). Adjustments in kilovoltage have a big impact on radiographic contrast: As kilovoltage (photon energy) is increased, the number of grays increases, thereby producing a longer scale of contrast. In general, as screen speed increases, so does contrast (resulting in a shorter scale of contrast). An increase in mAs is frequently accompanied by an appropriate decrease in kilovoltage, which would also shorten the contrast scale. SID and radiographic contrast are unrelated.
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Radiographers use monitoring devices to record their monthly exposure to radiation. The types of devices suited for this purpose include the
1. pocket dosimeter. 2. TLD. 3. OSL dosimeter. |
C. 2 and 3 only
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The OSL is rapidly becoming the most commonly used personnel monitor today. Film badges and TLDs have been used successfully for years. A pocket dosimeter is used primarily when working with large amounts of radiation and when a daily reading is desired.
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Which of the following positions demonstrates all the paranasal sinuses?
A. Parietoacanthial B. PA axial C. Lateral D. True PA |
C. Lateral
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The parietoacanthial (Waters' method) projection demonstrates the maxillary sinuses. The PA axial with a caudal central ray (Caldwell) demonstrates the frontal and ethmoidal sinus groups. The lateral projection, with the central ray entering 1 inch posterior to the outer canthus, demonstrates all the paranasal sinuses. X-ray examinations of the sinuses should always be performed erect, to demonstrate leveling of any fluid present.
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Immature cells are referred to as
1. undifferentiated cells. 2. stem cells. 3. genetic cells. |
B. 1 and 2 only
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Cells are frequently identified by their stage of development. Immature cells may be referred to as undifferentiated or stem cells. Immature cells are much more radiosensitive than mature cells.
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Radiation dose to personnel is reduced by which of the following exposure control cord guidelines?
1. Exposure cords on fixed equipment must be very short. 2. Exposure cords on mobile equipment should be fairly long. 3. Exposure cords on fixed and mobile equipment should be of the coiled expandable type. |
B. 1 and 2 only
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Radiographic and fluoroscopic equipment is designed to help decrease the exposure dose to patient and operator. One of the design features is the exposure cord. Exposure cords on fixed equipment must be short enough to prevent the exposure from being made outside the control booth. Exposure cords on mobile equipment must be long enough to permit the operator to stand at least 6 feet from the x-ray tube.
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The contrast media of choice for use in myelography are
A. ionic non-water-soluble. B. ionic water-soluble. C. nonionic water-soluble. D. gas. |
C. nonionic water-soluble.
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The contrast media of choice for use in myelography are nonionic water-soluble. For years, Pantopaque, a non-water-soluble (ethyl ester) contrast agent, was used for radiographic demonstration of the spinal canal. Because it was nonsoluble, it had to be removed after the procedure. Metrizamide was the first nonionic contrast agent introduced for use in myelography, but it has been replaced with iohexol and iopamidol, which are cheaper and safer and do not dissipate as quickly. Ionic contrast media are not used for intrathecal injections because they are too toxic, and gas or air does not provide adequate demonstration.
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