Chapter 6 - 2

Question 1

35. If the image size measures 4.6 in, and the magnification factor is 1.42, what is the size of the object?

a. 2.43 in
b. 3.24 in
c. 3.63 in
d. 6.53 in

Answer 1

b. 3.24 in

In order to determine object size, the image size is divided by the magnification factor; in this case 4.6 in is divided by 1.42.
REF: p.165

Question 2

36. Shape distortion can be created by:

a. off-centering the central ray.
b. angling the central ray.
c. increasing the SID.
d. A and B only.

Answer 2

d. A and B only.

Shape distortion results from misalignment or angulation of the tube, part, or image receptor.
REF: p.165

Question 3

37. The SOD can be determined by:

a. adding SID and OID.
b. adding the MF to the OID.
c. subtracting the OID from SID.
d. subtracting the SID from the MF.

Answer 3

c. subtracting the OID from SID.

The source-to-object distance (SOD) can be calculated by subtracting the OID from the SID.
REF: p.163

Question 4

38. What effect will increasing SID have on recorded detail?

a. Increased recorded detail
b. Decreased recorded detail
c. No effect on recorded detail

Answer 4

a. Increased recorded detail

Increasing SID increases recorded detail by reducing the amount of geometric unsharpness and decreasing size distortion.
REF: p.173

Question 5

39. For every ______ of part thickness, the radiographer should adjust the mAs by a factor of two.

a. 2 to 3 cm
b. 4 to 5 cm
c. 6 to 7 cm
d. 8 to 9 cm

Answer 5

b. 4 to 5 cm

For every increase of 4 to 5 cm of part thickness, the mAs should be doubled. It should be halved when the part is 4 to 5 cm thinner.
REF: p.172

Question 6

40. If the first radiograph of a foot is done using 4 mAs at 40 in, and a second radiograph is done using 50 in, how much mAs should be used to maintain exposure to the IR?

a. 1 mAs
b. 2 mAs
c. 6 mAs
d. 12 mAs

Answer 6

c. 6 mAs

According to the mAs/distance compensation formula, increasing the distance from 40 to 50 in will require an increase of mAs from 4 to 6 in order to maintain exposure to the IR.
REF: p.160

Question 7

41. In film-screen imaging, reducing the area of exposure (increasing collimation) ______ image contrast.

a. increases
b. decreases
c. has no effect on

Answer 7

a. increases

Increased collimation (a smaller field size) reduces the amount of scatter produced by the tissue and therefore increases the image contrast, because less scatter radiation reaches the image receptor.
REF: p.169

Question 8

42. Assuming all produce appropriate density images, which of the following would be the best exposure technique choice when performing a chest radiograph on an infant?

a. Use 40 ms exposure time.
b. Use 60 ms exposure time.
c. Use 200 ms exposure time.
d. Use at least 80 kVp.

Answer 8

a. Use 40 ms exposure time.

When imaging an infant for a chest radiograph, a short exposure time is critical in order to stop patient motion.
REF: p.169

Question 9

43. With all other factors remaining the same, a patient with which body habitus would require the highest exposure factors?

a. Asthenic
b. Sthenic
c. Hypersthenic
d. Hyposthenic

Answer 9

c. Hypersthenic

The hypersthenic patient has a large, stocky build and will require the highest exposure factors.
REF: p.170

Question 10

44. The property of the x-ray beam that impacts the unsharpness on the radiograph is beam:

a. quality.
b. quantity.
c. divergence.
d. restriction.

Answer 10

c. divergence

Due to the divergence of the x-ray beam, a geometric relationship exists among the source of x-rays, the object, and the image receptor.
REF: p.158

Question 11

45. Once the part has been penetrated, a doubling of the mAs results in __________ the exposure to the IR.

a. one fourth
b. one half
c. two times
d. four times

Answer 11

c. two times

Only after the part has been adequately penetrated, doubling mAs results in twice the exposure to the IR.
REF: p.172

Question 12

46. Which of the following mA and exposure time combinations does not produce 12 mAs?

a. 200 mA at 0.06 s
b. 400 mA at 0.03 s
c. 600 mA at 20 ms
d. 800 mA at 0.15 s

Answer 12

d. 800 mA at 0.15 s

800 mA at 0.15 s results in 120 mAs.
REF: p.149

Question 13

47. For film-screen imaging, density is controlled by:

a. mA.
b. exposure time.
c. mAs.
d. all of the above.

Answer 13

d. all of the above.

mAs, consisting of mA and exposure time, control film-screen density.
REF: p.151

Question 14

48. With film-screen imaging, increasing the kVp results in an image with __________ density and __________ contrast.

a. decreased; lower
b. decreased; higher
c. increased; lower
d. increased; higher

Answer 14

c. increased; lower

With film-screen imaging, increasing the kVp results in an image with increased density and lower (more gray) contrast.
REF: p.152

Question 15

49. With digital imaging, if lower than needed kVp is set, the image will have __________ brightness and __________ quantum mottle.

a. very low; increased
b. appropriate; increased
c. excessive; decreased
d. unacceptable; decreased

Answer 15

b. appropriate; increased

With digital imaging, if too low kVp is set, the image will have appropriate brightness (due to the computer making the adjustment) and increased quantum mottle.
REF: p.152

Question 16

50. With digital imaging, using twice as much mAs as needed will result in an image with __________ brightness and __________ patient exposure.

a. appropriate; increased
b. appropriate; appropriate
c. excessive; increased
d. excessive; appropriate

Answer 16

a. appropriate; increased

With digital imaging, using twice as much mAs as needed will result in an image with appropriate brightness (due to the computer making the adjustment) and increased patient exposure.
REF: p.150

Question 17

51. Knowing that 6 mAs is appropriate for a knee examination done at 40 in SID, how much mAs should be used at 56 in SID?

a. 1.5 mAs
b. 3 mAs
c. 12 mAs
d. 24 mAs

Answer 17

c. 12 mAs

As a rule of thumb, changing from 40 in SID to 56 in SID requires twice as much mAs.
REF: p.161

Question 18

52. Which of the following is not affected by a change in SID?

a. Recorded detail
b. Image contrast
c. Amount of radiation reaching the IR
d. Magnification

Answer 18

b. Image contrast

Image contrast is not affected by SID changes.
REF: p.161

Question 19

53. The radiographic grid is located:

a. inside the x-ray tube.
b. between the tube and patient.
c. between the patient and the IR.
d. beneath the IR.

Answer 19

c. between the patient and the IR.

In order to absorb the scattered radiation exiting the patient, the grid is located between the patient and IR.
REF: p.167

Question 20

54. With film-screen imaging, decreasing collimation (using a larger field size) results in __________ image contrast and __________ patient exposure.

a. lower; higher
b. lower; lower
c. higher; higher
d. higher; lower

Answer 20

a. lower; higher

With film-screen imaging, decreasing collimation (using a larger field size) results in lower image contrast (due to increased scatter) and higher patient exposure.
REF: p.169

Question 21

55. Increasing tube filtration results in an x-ray beam with __________ quantity and __________ energy.

a. less; lower
b. less; higher
c. more; lower
d. more; higher

Answer 21

b. less; higher

Increasing tube filtration results in an x-ray beam with less quantity (due to increased attenuation by the filter) and higher energy (because the lower-energy photons were absorbed).
REF: p.170

Question 22

56. As compared to a patient with a 24 cm thick abdomen, imaging a patient with a 20 cm thick abdomen will result in __________ scatter being produced and __________ image contrast.

a. less; lower
b. more; lower
c. less; higher
d. more; higher

Answer 22

c. less; higher

As compared to a patient with a 24 cm thick abdomen, imaging a patient with a 20 cm thick abdomen will result in less scatter being produced and therefore higher image contrast.
REF: p.172

Question 23

1 T/F With film-screen imaging, for a given exposure technique, increasing part thickness decreases radiographic density.

Answer 23

True

A thicker part absorbs more radiation, resulting in less exit radiation and reduced density on a film-screen image.
REF: p.172

Question 24

2 T/F Kilovoltage does not affect the quantity of exit radiation until adequate penetration is reached.

Answer 24

True

The area of interest must be adequately penetrated before kilovoltage can be adjusted to affect the quantity of exit radiation.
REF: p.152

Question 25

3 T/F The amount of mAs used has a direct effect on the density of a film-screen image.

Answer 25

True Increasing the mAs used with film-screen imaging will increase image density, and decreasing mAs will reduce image density. REF: p.152

Question 26

4 T/F Changes in kVp do not affect the digital exposure indicator.

Answer 26

False Increasing kVp will increase beam transmission, resulting in more radiation reaching the IR and a change in the exposure indicator. REF: p.152

Question 27

5 T/F In order to see the effect of changing kVp, a greater change is needed when operating at low kVp as compared to high kVp.

Answer 27

False In order to see the effect of changing kVp, a greater change is needed when operating at high kVp as compared to low kVp. REF: p.152

Question 28

6 T/F Film-screen images should be produced with very high kVp and very low mAs in order to reduce patient exposure.

Answer 28

False While high kVp and low mAs will reduce patient exposure, film-screen image contrast is dependent on the kVp being used. Using a higher kVp will reduce image contrast, which may negatively impact image quality. REF: p.155

Question 29

7 T/F Any increase in magnification results in a decrease in recorded detail.

Answer 29

True The greater the magnification, the less the recorded detail. REF: p.165

Question 30

8 T/F When choosing a grid for an examination, the grid with the highest grid ratio should always be selected in order to most improve image contrast.

Answer 30

False The highest grid ratio will result in a requirement for more mAs. The image contrast improvement and patient exposure need to be balanced. REF: p.167

Question 31

9 T/F As compared to a three-phase x-ray unit, a single-phase unit requires higher exposure techniques to produce a comparable image.

Answer 31

True A single-phase x-ray unit operates less efficiently than does a three-phase, resulting in higher exposure factors being used to produce comparable images. REF: p.169

Question 32

10 T/F With digital imaging, the same mAs and kVp should be used for an AP lumbar spine and a lateral lumbar spine.

Answer 32

False The thickness of the part is significantly greater for the lateral lumbar spine as compared to the AP projection. Therefore, more radiation is needed in order to produce a quality image. REF: p.172

Question 33

11 T/F With digital imaging, exposure factors do not need to be adjusted in order to visualize soft tissue.

Answer 33

True Because computer postprocessing techniques can be used to adjust the digital image brightness and contrast, exposure factors do not need to be adjusted in order to visualize soft tissue. REF: p.172