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Image Processing And Production > Ch. 6 > Flashcards

Ch. 6 Flashcards

1
Q

The product of milliamperage and exposure time is _______ to the quantity of x-rays produced.

A

directly proportional

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2
Q

As mAs increases, the quantity of radiation reaching the IR

A

Increases

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3
Q

If you were to select 250 mA and 0.5s on the control panel, how much mAs would be created?

A

125 mAs

mA x time = mAs

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4
Q

The original exposure to the IR is 100mA at 125ms. Which of the following exposure techniques would decrease the IR exposure by about 1/2?

200 mA at 31ms
100 mA at 0.063.s
50 mA at 0.125 s
All the above

A

All the above

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5
Q

The original technique is 300 mA at 50ms. If the mA is increased to 500, what exposure time will maintain the same exposure to the IR?

0.030 s
0.30 s
3 ms
15 ms

A

0.030 s

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6
Q

The original technique is 50mA at 0.20s. Which of the following exposure techniques will maintain the same exposure to the IR?

100 mA at 0.10 s and 200 mA at 0.05 s
100 mA at 0.10 s and 400 mA at 25 ms
200 mA at 0.05 s and 400 mA at 25 m
All are correct

A

All are correct

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7
Q

Which of the following is correct regarding the effect mAs has on the displayed digital image?
A. Increases brightness.
B. Decreases brightness.
C. Does not control brightness.
D. Increases contrast

A

Does not control brightness

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8
Q

Increased quantum noise is seen in a digital image with:

A

severely lower-than-needed mAs

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9
Q

If the exposure indicator value indicates too little radiation reaching the IR and the image displays increased quantum noise, what technique change would be best?

A

increase kVp by 15% and double mAs

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10
Q

The numerical value that is displayed on the processed image to indicate the level of x-ray exposure received on the digital image receptor is the

A

Exposure indicator

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11
Q

Which of the following technical factors affects the exposure to the IR by altering the amount and penetrating ability of the x-ray beam?

a. kVp
b. mA
c. Seconds
d. SID

A

kVp

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12
Q

In order to reduce patient exposure, what exposure factors should be considered?

A

higher kVp, lower mAs

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13
Q

A high kVp results in:

A less variation in the x-ray intensities exiting the patient.
B decrease interactions from Compton scattering.
C high-contrast image.

A

A) less variation in the x-ray intensities exiting the patient.

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14
Q

How much change in kVp will change the radiation exposure to the IR by a factor of 2?

A

15%

The 15% rule states that increasing or decreasing the kVp by 15% has the same effect as doubling or halving the mAs

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15
Q

The original technique is 80kVp at 20 mAs. If the kVp is increased to 92, what change in mAs will maintain the exposure to the IR?

A

10 mAs

A 15% increase in kVp, requires ½ the mAs to maintain a similar exposure to the IR.

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16
Q

The original technique is 80 kVp at 20 mAs. If the kVp is decreased to 68, what change in mAs will maintain the exposure to the IR?

A

40 mAs

Double your mAs

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17
Q

During the selection of the focal spot size, the radiographer is really determining the:

A

Actual size of the filament used

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18
Q

The distance between the radiation source and the image receptor is the:

A

SID

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19
Q

The relationship between distance and x-ray beam intensity, specifically that the intensity of the x-ray beam is inversely proportional to the square of the distance from the source, is the:

A

Inverse square law

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20
Q

If a person stands 3 feet from the source of exposure, receives an exposure of 160 mR, and then moves to 6 feet from the source of exposure, what would be the new exposure according to the ISL?

A

40 mR

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21
Q

If a person stands 12 feet from the source of exposure, receives an exposure of 60 mR, and then moves to 3 feet from the source of exposure, what would be the new exposure according to the ISL?

A

960 mR

According to the inverse square law, decreasing the distance from the x-ray source from 12 to 3 feet (factor of four) will result in an increase of exposure from 60 to 960 mR.

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22
Q

The distance between the object being imaged and the IR is the:

A

OID

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23
Q

When the SID is divided by the SOD, what is the result called?

A

Magnification Factor

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24
Q

If the first image of a chest is done using 72 in and 12 mAs, and a second image is done using 40 in, how much mAs should be used to maintain exposure to the IR?

A

4 mAs

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25
Q

A quality radiographic image is done using 10 mAs, 70 kVp, and a 12:1 ratio grid. How much mAs is needed to produce an image with the same exposure to the IR when the grid is removed?

A

2 mAs

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26
Q

The original technique is 80 kVp at 20 mAs using an 8:1 grid ratio. What change is mAs is needed if changing to a 16:1 grid ratio?

A

30 mAs

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27
Q

The misrepresentation of the size of an object is:

A

Magnification

28
Q

In order to image a structure that is located anteriorly in the body, it is best radiographed to minimize magnification by doing a(n) _______ projection

A

posterior-anterior (PA)

29
Q

Magnification is affected by:

A

SID

30
Q

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

A

3.24 in

image size divided by magnification factor

SID OVER SOD

31
Q

Shape distortion can be created by:

A

decreasing SOD angling the central ray

32
Q

The SOD can be determined by:

A

subtracting the OID from SID

33
Q

What effect will increasing SID have on spatial resolution?

A

increasing spatial resolution

34
Q

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

A

4-5 cm

35
Q

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

6 mAs

(New SID)² = 50²
(Old SID)² = 40²
New mAs = (50²/40²) * 4 mAs = 6.4 mAs

36
Q

Assuming all produce appropriate diagnostic 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.

A

A. Use 40 ms exposure time.

Shortest possible exposure time

37
Q

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

A

hypersthenic

38
Q

The property of the x-ray beam that impacts the unsharpness on the image is the beam:

A

divergence

39
Q

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

A

two times

40
Q

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

A

D. 800 mA at 0.15 s

mA x time

800 mA at 0.15 s results in 120 mAs

41
Q

If lower than needed kVp is selected, the digital image will have:

A

higher subject contrast and increased quantum noise

42
Q

Using twice as much mAs as needed will result in

A

adequate image brightness and unnecessary patient radiation exposure

43
Q

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

12 mS

44
Q

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

A. Spatial resolution
B. Image contrast
C. Amount of radiation reaching the IR
D. Magnification

A

Image contrast

45
Q

The radiographic grid is located

A

between the patient and the IR

46
Q

Decreasing collimation results in:

A. increased fog and lower image contrast
B. increased fog and increased patient exposure
C. lower image contrast and increased patient exposure
D. all options are correct

A

ALL

47
Q

Decreasing collimation results in

A

increased fog, lower image contrast, increased patient exposure

48
Q

Increasing tube filtration results in an x-ray beam with:

A

fewer photons and higher energy

49
Q

As compared to a patient with a 24 cm thick abdomen, imaging a patient with a 20 cm thick abdomen will result in:

A. less scatter and increased spatial resolution
B. less scatter and higher contrast
C. increased spatial resolution and higher contrast
D. all options are correct

A

D. all options are correct

50
Q

Increasing part thickness decreases image contrast:

true or false?

A

True

51
Q

Kilovoltage does not affect the quantity of exit radiation until adequate penetration is reached

T or F

A

True

52
Q

The amount of mAs used controls image brightness

T or F

A

False

mAs does not control brightness!

53
Q

Changes in kVp do not affect the exposure indicator value

T or F

A

False

54
Q

Any increase in magnification results in a decrease in spatial resolution

T or F

A

True

55
Q

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.

T or F

A

False

56
Q

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

T or F

A

True

57
Q

The same mAs and kVp should be used for an AP lumbar spine and a lateral lumbar spine.

T or F

A

False

58
Q

To reduce patient radiation exposure, is it best to use a lower kVp and higher mAs.

A

False

You want to use high kVp and low mAs!

58
Q

OID affects magnification, spatial resolution, contrast, and exposure to the IR.

A

True

59
Q

KNOW GRID CONVERSIONS

A
60
Q

no grid, conversion?

A

1

61
Q

5:1 grid conversion?

A

2

62
Q

6:1 gird conversion is?

A

3

63
Q

8:1 grid conversion?

A

4

64
Q

12:1 grid conversion?

A

5

65
Q

16:1 grid conversion?

A

6

Image Processing And Production (8 decks)

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