problem set 7

Digital fluoroscopy with a charge-coupled device has lower _______ and higher _______ than conventional fluoroscopy. Select one: a. detective quantum efficiency, maintenance b. light sensitivity, patient dose c. signal-to-noise ratio, patient dose d. patient dose, light sensitivity

patient dose, light sensitivity

Hybrid imaging can produce the highest-quality digital fluoroscopy images only if ________. Select one: a. energy subtraction is used b. patient motion is controlled c. remasking is employed d. remasking is completed

patient motion is controlled

The approximate pixel size for a 12-inch flat panel detector and 256 reconstruction matrix is: Select one: a. 0.4 mm b. 0.8 mm c. 2.5 mm d. 4 mm e. 1.0 mm

1.0 mm

The minimum acceptable TV signal-to-noise ratio for digital fluoroscopy is: Select one: a. 200:1 b. 1000:1 c. 2000:1 d. 100:1 e. 5000:1

1000:1

Digital fluoroscopy uses at least _____ monitor(s). Select one: a. 2 b. 1 c. 3 d. 4

2

During 5 minutes of digital fluoroscopy, a typical dose is: Select one: a. 200 rad b. 5 mGy c. 500 rad d. 200 mGy e. 500 mGy

200 mGy

The maximum frame acquisition rate in digital fluoroscopy is about: Select one: a. 30 frames per second b. 4 frames per second c. 60 frames per second d. 10 frames per second e. 1 frame per second

30 frames per second

Which of the following components found in digital fluoroscopy is NOT found in conventional fluoroscopy? Select one: a. An ABS b. A video monitor c. An image intensifier d. An ADC e. A source-to-image receptor distance (SID) indicator

An ADC

A charge-coupled device used in digital fluoroscopy provides high ____________. Select one: a. spatial resolution b. signal-to-noise ratio c. detective quantum efficiency d. All of the above

All of the above

Remasking may be required due to _________. Select one: a. noise artifacts b. motion artifacts c. technical factors d. Any of the above

Any of the above

Which of the following is NOT an advantage of flat-panel detectors over CCDs coupled to image intensifiers digital fluoroscopy? Select one: a. Improved contrast resolution b. Distortion-free images c. High DQE d. Constant image quality e. Higher spatial resolution

Higher spatial resolution

Energy subtraction technique takes advantage of the difference in _______ during contrast injection. Select one: a. patient thickness b. Compton scatter c. K-edge absorption d. tissue density

K-edge absorption

Which of the following is NOT an advantage of charge-coupled devices with regard to medical imaging? Select one: a. Low cost b. Low patient dose c. High SNR d. High spatial resolution e. Linear response

Low cost

An advantage of digital imaging over conventional imaging is which of the following? Select one: a. Reduced noise b. Reduced speed c. Post-processing d. Increased latitude e. Increased resolution

Post-processing

What is a characteristic of an IR x-ray tube? Select one: a. Small target angle b. 300,000-kHu anode heat capacity c. 50-kW power rating d. Large target angle e. Small-diameter anode disc

Small target angle

Digital fluoroscopic dose rate is lower than that for continuous analog fluoroscopy. Select one: a. True b. False

True

Compared with conventional fluoroscopy, digital fluoroscopy is conducted: Select one: a. at much lower x-ray tube current b. with a different type of video monitor c. with higher capacity x-ray tubes d. at much higher x-ray tube current e. with a different type of image intensifier

at much higher x-ray tube current

The time-interval delay mode is principally used in __________ imaging. Select one: a. cardiac b. barium enema c. renal angiography d. run-off

cardiac

A principle advantage of digital fluoroscopy over conventional fluoroscopy for subtraction studies is: Select one: a. examination speed b. noise enhancement c. less contrast material d. contrast enhancement e. low patient dose

contrast enhancement

The mask image is usually the: Select one: a. image at the peak of contrast b. image just preceding contrast c. last image d. first image e. last contrast image

first image

The combination of temporal and energy subtraction techniques is called _________. Select one: a. dual subtraction b. superimposition c. hybrid subtraction d. interlacing mode subtraction

hybrid subtraction

A principal advantage of digital fluoroscopy is the _____________. Select one: a. progressive mode b. image acquisition rate c. dynamic range d. image subtraction

image subtraction

Image integration in digital fluoroscopy results in _______. Select one: a. decreased contrast resolution b. increased noise artifact c. decreased patient dose d. increased patient dose

increased patient dose

The time it takes to turn on the digital fluoroscopy x-ray tube and reach the selected mA and kVp is the ________ time. Select one: a. acquisition b. interrogation c. extinction d. radiographic

interrogation

A CCD: Select one: a. is used instead of a TV camera tube b. is made of a-Se c. has more lag than a TV camera tube d. is used in conjunction with a TV camera

is used instead of a TV camera tube

If the same amount of imaging time occurs, compared to the dose in conventional fluoroscopy, the dose in digital fluoroscopy is: Select one: a. higher b. lower c. about the same d. it depends e. None of the above

lower

In mask mode, the ______ image is shown on monitor B, and the ______ image is shown on monitor A. Select one: a. mask, subtracted b. subtracted, mask c. hybrid, mask d. subtracted, hybrid

mask, subtracted

Digital fluoroscopy energy subtraction has less _________ than temporal subtraction. Select one: a. motion artifact b. x-ray intensity c. kVp switching d. complexity

motion artifact

A misregistration artifact: Select one: a. is not really an artifact b. usually follows a change in kVp c. requires more hardware than is usually available d. occurs when a patient moved e. cannot be corrected

occurs when a patient moved

Digital fluoroscopy systems with hybrid capabilities use both _____________. Select one: a. interlace and progressive modes b. charge coupled devices and TV monitors c. temporal and energy subtraction d. high mAs and low mass techniques

temporal and energy subtraction