Deck 9: Scatter Radiation and Its Control

Question 1

At what kVp levels do Compton interactions occur?

A) 40 kVp
B) 50 kVp
C) 80 to 125 kVp
D) 40 to 125, the entire diagnostic range

Answer 1

40 to 125, the entire diagnostic range

Question 2

A scattered photon has ________ energy than the incoming primary beam photon.

A) less
B) more
C) less, if the kVp is over 80
D) more, if the kVp is over 80

Answer 2

less

Question 3

The interactions that produce scatter radiation occur primarily in the:

A) tabletop.
B) image receptor.
C) patient.
D) tube housing.

Answer 3

patient.

Question 4

The device that is placed between the patient and the IR to absorb scatter radiation is called a:

A) grid.
B) filter.
C) gonad shield.
D) cassette.

Question 5

If the body part is thicker or larger,the amount of scatter radiation fog will:

A) increase.
B) decrease.
C) remain the same.
D) increase, depending on the kVp level.

Question 6

Compton scatter that is directed from the patient back toward the x-ray tube is called:

A) backscatter.
B) front scatter.
C) side scatter.
D) coherent scatter.

Question 7

Which of the following factors affects the quantity of scatter radiation fog on a radiograph?
1.Field size
2.Focal spot size
3.kVp

A)1 and 2 only
B) 1 and 3 only
C) 2 and 3 only
D) 1, 2, and 3

Question 8

Scatter radiation affects radiographic appearance by causing:

A) increased distortion.
B) increased recorded detail.
C) decreased contrast.
D) decreased density.

Question 9

Field size

Question 10

Focal spot size

Question 11

The most effective and practical way to reduce scatter radiation fog on a radiograph is to:

A) decrease the OID.
B) decrease the SID.
C) increase the kVp.
D) use a grid.

Question 12

kVp

A) 1 and 2 only
B) 1 and 3 only
C) 2 and 3 only
D) 1, 2, and 3

Question 13

The number of lead strips per inch is called:

A) grid radius.
B) grid ratio.
C) focal range.
D) grid frequency.

Question 14

How does scatter radiation fog reduce the visibility of detail in a radiographic image?

A) By increasing contrast
B) By increasing distortion
C) By decreasing contrast
D) By decreasing distortion

Question 15

What is the principal source of scatter radiation in radiography?

A) Tube housing
B) Patient
C) Table
D) Collimator

Question 16

The photoelectric effect occurs when an incoming photon from the primary beam interacts with which part of the atom in a patient's body?

A) Inner shell electron
B) Outer shell electron
C) Nucleus-protons
D) Nucleus-neutrons

Question 17

If the size of the x-ray field increases,what happens to scatter radiation fog?

A) It increases.
B) It decreases.
C) It remains the same.
D) It increases for the thorax, abdomen, and pelvis projections only.

Question 18

Compton scatter occurs when an x-ray photon interacts with which part of the atom in the patient's body?

A) Inner shell electron
B) Outer orbital electron
C) Nucleus-protons
D) Nucleus-neutrons

Question 19

Which of the following statements is true? If the kVp increases,the:

A) number of photoelectric interactions increases.
B) scatter radiation fog increases.
C) Compton and photoelectric interactions increase.
D) Compton and photoelectric interactions decrease.

Question 20

As compared to an 8:1 grid,a grid with a 12:1 ratio will:

A) clean up scattered radiation less effectively.
B) require less precise centering.
C) require more exposure to make a satisfactory radiograph.
D) produce less radiographic contrast.

Question 21

As a general rule,a grid should be employed when the part thickness is greater than:

A) 4 cm.
B) 10 cm.
C) 18 cm.
D) 12 in.

Question 22

The radiographic appearance of decreased density on the lateral margins of the image is most likely caused by grid:

A) frequency.
B) motion.
C) ratio.
D) cutoff.

Question 23

What is one of the most important things a limited operator can do to control scatter radiation?

A) Reduce the thickness of the part.
B) Maintain the correct field size.
C) Use the exposure technique chart.
D) Use the correct grid.

Question 24

When performing the collimator test,the four sides of the collimator must each be within ___% of the SID to be in control.

A) 1
B) 1.5
C) 2
D) 3

Question 25

If a grid is misaligned with the central ray,it can cause a light area on the side of the image called:

A) coherent scattering.
B) parallax effect.
C) grid cut-off.
D) attenuation.

Question 26

Scatter radiation fog will:
1) increase density.
2) decrease contrast.
3) reduce the visibility of detail.

A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1, 2, and 3

Question 27

As kVp is increased,photoelectric effect interactions will:

A) increase.
B) decrease.
C) remain the same.
D) increase only above 60 kVp.

Question 28

When performing the beam alignment test,the x-ray tube must be within ____ degree(s)of perpendicular to be in control.

A) 1
B) 1.5
C) 2
D) 3

Question 29

How will the density,or atomic number,of the absorbing matter affect scatter?

A) It will decrease.
B) It will increase.
C) It will not affect scatter.
D) It will affect scatter only if the body part is greater than 10 cm.

Question 30

As kVp is increased,Compton interactions will:

A) increase.
B) decrease.
C) remain the same.
D) increase only above 60 kVp.

Question 31

Grid cut-off will occur when the:
1) tube is off-center.
2) tube is tilted.
3) SID is too great.

A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1, 2, and 3

Question 32

Grids with lead strips that are aligned to coincide with the primary beam angle are called _____ grids.

A) crosshatch
B) focused
C) parallel
D) Bucky

Question 33

During the photoelectric effect,an incoming photon interacts with the atom in the patient's body. What happens to the photon with this effect?

A) It scatters out of the body.
B) It is totally absorbed by the atom.
C) It scatters to a nearby atom.
D) It is totally absorbed by a nearby atom.

Question 34

Which of the following reduces the amount of scatter radiation fog on a radiograph?
1) Decrease in kVp
2) Decrease in field size
3) Decrease in grid ratio

A) 1 and 2 only
B) 1 and 3 only
C) 2 and 3 only
D) 1, 2, and 3

Question 35

Which of the following is used to check the collimator and beam alignment of the overhead tube crane?

A) Wire test mesh
B) Densitometer
C) Collimator template and beam alignment cylinder
D) Collimator template and wire test mesh

Question 36

What prevents the lead strips in the grid from being seen on the radiograph?

A) The grid oscillates.
B) The grid strips are parallel to the beam.
C) The kVp is above 60.
D) The lead strips blend in with kVp settings over 60.