C11: Review Questions

Question 1

The radiographic beam should be collimated so that it is which of the following?

Answer 1

no larger than the image receptor

Question 2

Both alignment and length and width dimensions of the radiographic and light beams must correspond to within:

Answer 2

2% of the SID

Question 3

What is the function of a filter in diagnostic radiology?

Answer 3

to decrease the x-radiation dose to the patient’s skin and superficial tissue

Question 4

HVL may be defined as the thickness of a designated absorber required to do which of the following?

Answer 4

decrease the intensity of the primary beam by 50% of its initial value

Question 5

The photostimulable phosphor in the computed radiography imaging plate is more sensitive to scatter radiation before and after it is sensitive to scatter radiation before and after it is sensitized through exposure to a radiographic beam. Because of this increased sensitivity, which of the following is true?
1. five millimeters of added aluminum equivalent filtration must always be used during routine CR imaging
2. a radiographic grid may be used more frequently during CR imaging
3. any source-to-image receptor distance can be used during CR imaging without adjustment in technical exposure factors

Answer 5

2 only

Question 6

To minimize skin exposure to electrons produced by photon interaction with the collimator, how far below the collimator should the patient’s skin surface be?

Answer 6

at least 15 cm below

Question 7

Which of the following aluminum equivalents for total permanent filtration meets the minimum requirement for mobile diagnostic and fluoroscopic equipment?

Answer 7

2.5 mm aluminum equivalent

Question 8

The trough, or bilateral wedge filter, which is used in some dedicated chest radiographic units, is an example of which of the following?

Answer 8

compensating filter

Question 9

To decrease patient exposure during fluoroscopic procedures, the fluoroscopist can:
1. limit the size of the fluoroscopic field to include only the area of anatomy that is of clinical interest
2. employ the practice of pulsed fluoroscopy to reduce the overall length of exposure
3. choose to use a conventional fluoroscope instead of an image intensification fluoroscope

Answer 9

1 and 2 only

Question 10

A diagnostic-type protective tube housing must be constructed so that leakage radiation measured at a distance of 1 m from the x-ray source dose not exceed _____ when the tube is operated at its highest voltage at the highest current that allows continuous operation.

Answer 10

1 Gya/hr

Question 11

Which of the following changes might improve the visibility of vessels in an interventional angiography study but may cause harm to the patient?

Answer 11

increase the amount of contrast material

Question 12

Pulsed, or intermittent, fluoroscopy involves manual or automatic periodic activation of the fluoroscopic x-ray tube by the fluoroscopist, rather than continuous activation. Which of the following are benefits of this practice?
1. automatically magnifies the fluoroscopic image
2. helps to extend the life of the x-ray tube
3. significantly decreases patient dose, especially in long procedures

Answer 12

2 and 3 only

Question 13

A resettable device on a fluoroscopic unit that measures the collective x-ray beam-on time and sounds an audible alarm or in some cases interrupts the exposure after the fluoroscope has been activated for 5 minutes is termed a:

Answer 13

cumulative timer

Question 14

Non-digital fluoroscopy involves the use of a signal amplification device called an:

Answer 14

image intensifier tube

Question 15

When changing one mA station to a neighboring mA station, the most linearity can vary is:

Answer 15

10%