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20 Cards in this Set
- Front
- Back
Advantages of CR/DR include all of the following, except the ability to: |
Improve geometric detail. - Geometric detail is controlled only by SID, OID, and focal spot size. These factors are fixed during x-ray exposure. |
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The typical requirements for a fixed x-ray table used for fluoroscopy include the ability to: |
Move 30 degrees Trendelenburg &Move upright 90 degrees. - Most x-ray/fluoroscopic equipment is "fixed", meaning it was installed and cannot be moved. |
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In the production of Bremsstrahulung radiation, the incident electron: |
Is deflected with resulting energy loss. - "Brems" radiation is 1 of 2 types of x-rays produced at the tungsten target. The incident high-speed electron passing through tungsten atom is attracted by positively charged nucleus; therefore deflected from its course = loss of energy. |
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Which of the following will occur as a result of decreasing the anode target angle? |
Effective focal spot size will decrease - As target angle decreases (gets steeper/smaller) the effective focal spot becomes smaller = improved detail. Greater photon intensity toward the cathode side of the x-ray tube - With smaller target angle, anode heel effect increases; photons more absorbed by heel = smaller % of photons at anode and more at the cathode. |
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Which of the following matrix sizes will result in the best spatial resolution? |
2,048 x 2,048 - As matrix size is increased, there are more pixels More pixels = smaller pixels Smaller pixels = improved resolution |
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Which of the following can be associated with mobile x-ray equipment? |
Wireless detector Meet chargeable batteries High-frequency output |
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Changes in window width in digital imaging result in changes in: |
Contrast. - "Windowing" = process of changing contrast and brightness setting on finished image. "Window width" = controls # of shades of gray in the image (contrast) "Window level" = image brightness |
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If the primary coil of the high-voltage transformer is supplied by 220V and has 150 turns, and the secondary coil has 75,000 turn, what is the voltage induced in the secondary coil? |
110kV. - x 75,000 ------- = --------- 150x = 16,500,000 220 150 x = 110,000V = 100kV |
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Which of the following circuit devices operates on the principle of self-induction? |
"Self-induction" = characteristic of AC only Autotransformer - enable tech to vary kilovoltage Choke coil - type of variable resistor used to regulate filament current |
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All of the following are components of the CT gantry, except: |
Gantry = includes x-ray tube, detector array, a high-voltage generator, a collimator assembly, slip rings, digital acquistion system, and laser beams. Console = used only to operate CT machine, select exam protocols, and patient information |
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Radiographers from a particular three-phase, full-wave rectifier x-ray unit were underexposed, using known correct exposures. A synchronous spinning-top test was performed using 100mA, 1/20 second, and 70kV, and a 12-degree arc is observed on the test image. What of the following is the most likely problem? |
*Because a three-phase, full-wave rectified current would expose a 360-degree arc per second, a 1/20-second exposure should expose an 18-degree arc* The 1/20-second time station is inaccurate. |
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HVL (half value layer) is influenced by: |
*The thickness of any absorber that will reduce x-ray beam intensity to 1/2 its original value* kV level Total filtration |
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Focal spot size can be evaluated using a |
Focal spot size accuracy is directly related to the degree of geometric blur; focal spot size increases = blur increases Slit camera. - measure the physical size of focal spot |
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Which of the following is usually recommended for cleaning PSPs? |
Should be cleaned monthly. Anhydrous ethanol. - place small amount on lint-free cloth to clean Dust on PSP = pinhole artifact |
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Proper care of leaded apparel includes: |
Periodic check for cracks. |
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Periodic equipment calibration includes testing of the: |
Focal spot - impact on image sharpness mA & kV - big impact on quality of finished image |
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An x-ray tube collimator assembly generally includes the following components: |
Shutters Mirrors - project size, location, and center of irradiated field |
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Which of the following contributes to inherent filtration? |
Inherent filtration = "built into" the tube Before exiting the tube, x-ray photons must pass through: X-ray tube glass envelope X-ray tube port window |
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By which of the following can poor screen-film contact be caused? |
*Perfect contact between the intensifying screens and the film is essential to maintain image sharpness* Damaged cassette frame Foreign body in cassette Warped cassette front |
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A quality assurance program includes checks on which of the following radiographic equipment conditions? |
Reproducibility - repeated exposures at given technical factors must provide consistent intensity Linearity - a given mAs, using different mA stations with appropriate exposure time adjustments, provides consistent intensity. Positive beam limitation - automatic collimation and must be accurate to 2% of SID. |