Deck 15: Beam Restriction

Question 1

Lead masks may serve as beam restrictors.

Answer 1

True

Question 2

As the kilovoltage increases, the percentage of photons that undergo a ____ interaction will decrease.

A)photoelectric
B)coherent
C)Compton
D)characteristic

Answer 2

photoelectric

Question 3

A radiographer can best reduce the amount of scatter radiation from reaching the receptor by

A)collimating.
B)beam restriction.
C)utilizing a grid.
D)all of the above

Answer 3

all of the above

Question 4

Soft tissue absorbs more radiation and produces more scatter than bone.

Question 5

Scatter radiation in radiography is produced during

A)Compton interactions.
B)photoelectric effect interactions.
C)coherent or classical interactions.
D)an annihilation interaction.

Question 6

A key factor that affects the amount of scatter produced is

A)kilovoltage.
B)milliamperage.
C)time.
D)anode composition.

Question 7

Which of the following is placed between the patient and the image receptor to absorb scatter radiation?

A)radiographic grid
B)AEC detector
C)collimator
D)cylinder

Question 8

The principal factors that affect the amount of scatter produced are mAs and the type of irradiated material.

Question 9

Image quality is improved when scatter reaching the image receptor is reduced.

Question 10

As the kilovoltage increases, the percentage of x-rays that undergo ____ interactions will increase.

A)photoelectric
B)coherent
C)Compton
D)bremsstrahlung

Question 11

Penumbra is a geometric unsharpness around the periphery of an image.

Question 12

A radiographer can best minimize the amount of scatter radiation reaching the image receptor by restricting the beam.

Question 13

PBLs may also filter the x-ray beam.

Question 14

Automatic collimators are known as positive beam limitation (PBL) devices.

Question 15

A factor that affects the amount of scatter produced is

A)the irradiated material.
B)milliamperage.
C)time.
D)anode composition.

Question 16

Scattered photons from Compton interactions are of no use in demonstrating radiographic structures of interest.

Question 17

Bone absorbs more radiation and produces more scatter than soft tissue.

Question 18

When kilovoltage is increased with no other changes in technical factors, fewer scattered photons will result.

Question 19

If an increase in kilovoltage is accompanied by a reduction in mAs, to maintain the same exit dose the overall result will be

A)a decrease in the amount of radiation produced.
B)a decrease in the amount of scatter produced.
C)an increase in the amount of radiation produced.
D)an increase in the amount of scatter produced.

Question 20

Scattered photons will

A)impair image quality.
B)add density to image receptor exposure.
C)not be considered part of the useful beam.
D)all of the above

Question 21

A diaphragm is placed 6 inches from the focal spot.The diameter of the opening in the aperture is a 3-inch circle.What would be the projected image size if the SID were 40 inches?

Question 22

When a beam-restricting device is used to limit field size, technical factors may need to ____ to compensate for the change in image receptor exposure.

A)be increased
B)be decreased
C)remain unchanged
D)none of the above

Question 23

The diameter of the lower rim of a cone is 4 inches.The bottom of the cone is placed at a distance of 10 inches from the focal spot.What will be the size of the projected image at a 40-inch SID?

Question 24

As more photons pass through the irradiated material unaffected, the resulting image receptor exposure has

A)greater image distortion.
B)less image distortion.
C)greater radiographic image density.
D)less radiographic image density.

Question 25

Placing a lead blocker adjacent to an obese patient's anatomy during a lateral lumbar spine radiograph

A)is unnecessary with today's digital receptors.
B)will improve image quality.
C)will reduce exposure to the patient.
D)will reduce exposure to the radiographer.

Question 26

Cones and cylinders would be commonly employed for the following examinations EXCEPT

A)orbits.
B)L5-S1 spot.
C)skull.
D)AP thoracic spine.

Question 27

Penumbra is ____ when the beam restrictor is at a/an ____ distance from the port.

A)reduced; increased
B)reduced; decreased
C)unchanged; increased
D)increased; increased

Question 28

All of the following are considered beam-restricting devices EXCEPT

A)aperture diaphragm.
B)beam filter.
C)positive beam limitation (PBL) device.
D)collimator.

Question 29

When more photons are absorbed photoelectrically, the resulting radiograph has

A)greater image distortion.
B)less image distortion.
C)greater radiographic image density.
D)less radiographic image density.

Question 30

The diameter of the lower rim of a cone is 5 inches.The bottom of the cone is placed at a distance of 15 inches from the focal spot.What will be the size of the projected image at a 40-inch SID?

Question 31

A diaphragm is placed 4 inches from the focal spot.The diameter of the opening in the aperture is a 2-inch circle.What would be the projected image size if the image receptor distance (SID) were 40 inches?

Question 32

The shutters of a collimator

A)regulate field size.
B)reduce penumbra.
C)reduce stem radiation.
D)all of the above

Question 33

The ____ the atomic number of the irradiated material, the ____ the number of photoelectric absorption interactions that occur.

A)higher; lower
B)higher; higher
C)lower; higher
D)lower; unaffected

Question 34

As the volume of irradiated tissue ____, the amount of scatter produced ____.

A)increases; increases
B)increases; decreases
C)decreases; increases
D)decreases; decreases

Question 35

When collimating down from a 14"x17" field size to a 8"x10" field size,:

A)mAs must be increased to maintain radiographic image density.
B)kVp must be increased to maintain image quality.
C)off-focus radiation production is increased.
D)the mAs should be reduced by 50%.

Question 36

Collimators that offer positive beam limitation (PBL) are very popular with technologists for a variety of reasons.Even though the federal requirement for PBL has been repealed, their popularity has continued and most department managers consider PBL as a "standard equipment" feature.PBL is electronically and mechanically highly engineered technology and subject to abuse by the inattentive and unprofessional radiographer.In the event of a PBL failure during an examination, what circumstances will be evident to the radiographer and what can he/she do to overcome the PBL error and continue with the procedure.

Question 37

The ____ the atomic number of the irradiated material, the ____ the number of photoelectric absorption interactions will be, and the ____ the scatter produced.

A)higher; lower; less
B)higher; higher; less
C)lower; higher; more
D)lower; lower; less

Question 38

An effective method for reducing scatter radiation production is the

A)15% rule of kVp change.
B)use of x-ray beam angulation.
C)use of an increased exposure time with mA compensation.
D)selection of small focal spot.

Question 39

The volume of the irradiated tissue increases as

A)field size and patient thickness increase.
B)patient density increases.
C)patient orientation to the beam changes.
D)tissue composition increases.

Question 40

The collimation assembly of a radiographic unit

A)employs an upper and lower set of shutter blades.
B)allows the radiographer to adjust the field size in a circular dimension.
C)removes the mirror assembly for exposures.
D)all of the above