Deck 11: Control of Scatter Radiation

Question 1

Federal regulations passed in _____ required that positive beam limiting devices be on all manufactured x-ray collimators.

A) 1954
B) 1974
C) 1994
D) 2000

Answer 1

1974

Question 2

Contrast resolution is improved by _____.

A) tight collimation
B) lowering kVp
C) patient compression
D) all of the above

Answer 2

all of the above

Question 3

The most commonly used beam restricting device is the _____.

A) extension cone
B) variable collimator
C) aperture diaphragm
D) compression device

Answer 3

variable collimator

Question 4

A fixed aperture diaphragm should leave a _____ cm unexposed border on the film.

A) 0.1
B) 0.5
C) 1
D) 2

Question 5

Approximately _____% of the x-ray beam incident on the patient is transmitted through the patient without interaction to become part of the image-forming beam.

A) 90-99
B) 80-89
C) 20-29
D) 0-9

Question 6

The x-ray interaction that contributes to the clear parts of the image is _____.

A) coherent scatter
B) Compton interaction
C) photoelectric interaction
D) pair production

Question 7

The x-rays that are transmitted through the patient without interaction contribute to _____.

A) useful information
B) film fog
C) image noise
D) all of the above

Question 8

Compton scatter contributes to _____.

A) useful information
B) image noise
C) image contrast
D) all of the above

Question 9

The use of _____ improves contrast and reduces patient dose.

A) collimation
B) high kVp
C) low kVp
D) less filtration

Question 10

Scatter radiation increases as _____ increases.

A) photoelectric absorption
B) field size
C) filtration
D) contrast

Question 11

How can you improve image contrast with a heavy patient without increasing patient dose?

A) Lower kVp and raise mAs.
B) Use tight collimation.
C) Raise kVp and lower mAs.
D) Do both A and B.

Question 12

Beam restriction with a(n)_____ is only accurate at a fixed SID.

A) aperture diaphragm
B) cone
C) collimator
D) PBL device

Question 13

Which kVp selection would result in the most scattered x-rays in the image-forming beam?

A) 90 kVp
B) 75 kVp
C) 60 kVp
D) 50 kVp

Question 14

The positive beam limiting device (PBL)assures that the x-ray beam is collimated to _____.

A) the exact part size
B) 1 cm inside image receptor size
C) the image receptor size
D) 1 cm outside image receptor size

Question 15

Photoelectric interactions increase when _____ is decreased.

A) mAs
B) patient thickness
C) filtration
D) kVp

Question 16

The use of a compression device will increase _____.

A) film fog
B) patient dose
C) contrast
D) scatter

Question 17

The three primary factors influencing the intensity of scatter in the image-forming beam are _____.

A) mAs, kVp, and collimation
B) mAs, filtration, and grids
C) kVp, field size, and patient thickness
D) filtration, patient thickness, and mAs

Question 18

Lowering kVp _____ patient dose and _____ image contrast.

A) lowers, decreases
B) increases, decreases
C) lowers, increases
D) increases, increases

Question 19

Image-forming x-rays include those which have been _____.

A) transmitted without interaction
B) scattered through Compton interaction
C) absorbed through photoelectric interaction
D) both A and B

Question 20

Decreasing the kVp will increase _____.

A) patient dose
B) image noise
C) Compton scatter
D) optical density