Deck 12: Scatter Control

Question 1

As compared with lower kVp exposures, when using high kVp will result in a scattered photon that is of ________ energy.

A) lower
B) higher
C) the same
D) half

Answer 1

higher

Question 2

The most easily adjusted radiographic beam-restricting device is the

A) aperture diaphragm
B) collimator
C) cone or cylinder
D) none of these

Answer 2

collimator

Question 3

Increasing collimation (decreasing the field size) results in

A) increased scatter production and higher contrast
B) increased scatter production and lower contrast
C) decreased scatter production and higher contrast
D) decreased scatter production and lower contrast

Answer 3

decreased scatter production and higher contrast

Question 4

The beam-restriction device that includes a visible light projecting the x-ray field size onto the patient is the

A) aperture diaphragm
B) collimator
C) cone or cylinder
D) none of these

Question 5

The two major factors that affect the amount of scatter radiation produced and exiting the patient are

A) kVp and mAs
B) volume of tissue irradiated and mAs
C) volume of tissue irradiated and kVp
D) kVp and the use of a grid

Question 6

The simplest type of beam-restricting device is a flat piece of lead with a hole in it called a(n)

A) aperture diaphragm
B) collimator
C) cone or cylinder
D) none of these

Question 7

When imaging the pelvis, changing from 14 * 17 collimation to 8 *10 collimation requires

A) an increase in kVp
B) a decrease in kVp
C) an increase in mAs
D) a decrease in mAs

Question 8

A flat piece of lead with a hole in it that has a flange directed toward the patient is a(n)

A) aperture diaphragm
B) collimator
C) cone or cylinder
D) none of these

Question 9

Increased collimation means :
1) Decreased field size
2) Increased field size
3) Less volume of tissue irradiated

A) decreased field size and increased field size only
B) decreased field size and less volume of tissue irradiated only
C) increased field size and less volume of tissue irradiated only
D) decreased field size, increased field size, and less volume of tissue irradiated

Question 10

The automatic collimator

A) automatically collimates to the anatomy of interest
B) is required by law on all new equipment
C) is seldom found on modern x-ray equipment
D) automatically collimates to the IR size

Question 11

The volume of tissue irradiated is determined by

A) the area of collimation
B) patient thickness
C) field size
D) all of these

Question 12

The beam-restriction device that results in images with the most unsharpness around the edge of the image is the

A) aperture diaphragm
B) collimator
C) cone or cylinder
D) none of these

Question 13

A significant amount of collimation will have what effect on the amount of radiation reaching the IR

A) reduced
B) increased
C) the same
D) none of these

Question 14

The most effective and often used radiographic beam-restriction device is the

A) aperture diaphragm
B) collimator
C) cone or cylinder
D) none of these

Question 15

The probability of a Compton interaction occurring is related to

A) the energy of the x-ray photon
B) the atomic number of the matter
C) the mAs used
D) all of these

Question 16

The unrestricted primary x-ray beam is

A) round
B) oval
C) square
D) rectangular

Question 17

Restriction of the primary beam to the anatomy of interest

A) reduces patient exposure
B) is a major cause of repeated images
C) reduces the amount of scatter produced
D) reduces patient exposure and reduces the amount of scatter produced

Question 18

For radiographic procedures, scatter radiation is primarily the result of

A) photoelectric interaction
B) pair production
C) Compton interaction
D) classical scattering

Question 19

Which of the following produces the greatest amount of scatter radiation exiting the patient?

A) Low kVp and small field size.
B) Low kVp and large field size.
C) High kVp and small field size.
D) High kVp and large field size.

Question 20

The field shape produced by a collimator is

A) round
B) oval
C) rectangular
D) all of these

Question 21

A linear grid

A) has lead strips that cross each other
B) has lead strips that travel in one direction
C) is the most common type of radiographic grid
D) has lead strips that travel in one direction and is the most common type of radiographic grid

Question 22

Which of the following is the formula used to determine grid ratio?

A) Grid ratio = distance between the lead strips/height of the lead strips.
B) Grid ratio = width of the lead strips/height of the lead strips.
C) Grid ratio = height of the lead strips/distance between the lead strips.
D) Grid ratio = height of the lead strips/width of the lead strips.

Question 23

Grids absorb scatter radiation because the scattered photons

A) have high energy
B) have extremely low energy
C) travel in the same direction as the transmitted photons
D) travel at an angle to the transmitted photons

Question 24

The grid is located

A) just below the x-ray tube window
B) between the patient and IR
C) just below the IR
D) between the x-ray tube and the patient

Question 25

The distance between the grid and the convergent line is the

A) convergent line
B) focal distance
C) convergent point
D) focal range

Question 26

The location in space where all the lines extended from the lead strips meet is the

A) convergent line
B) focal distance
C) convergent point
D) focal range

Question 27

Using a higher the grid ratio will
1) increase spatial resolution
2) increase scatter clean up
3) increase radiographic contrast

A) increase spatial resolution and increase scatter clean up only
B) increase spatial resolution and increase radiographic contrast only
C) increase scatter clean up and increase radiographic contrast only
D) increase spatial resolution, increase scatter clean up, and increase radiographic contrast

Question 28

If all the convergent points were connected along the length of the grid they would form the

A) convergent line
B) focal distance
C) convergent point
D) focal range

Question 29

Grids are typically used when:
1) Part measures more than 10 cm
2) At least 60 kVp needed for the exam
3) Part transmits little scatter radiation

A) part measures more than 10 cm and at least 60 kVp needed for the exam only
B) part measures more than 10 cm and part transmits little scatter radiation only
C) at least 60 kVp needed for the exam and part transmits little scatter radiation only
D) part measures more than 10 cm, at least 60 kVp needed for the exam, and part transmits little scatter radiation

Question 30

A grid with lead strips that run parallel to each other is a

A) parallel grid
B) focused grid
C) nonfocused grid
D) parallel grid and nonfocused grid

Question 31

The number of lead lines per inch or centimeter is the grid

A) number
B) ratio
C) frequency
D) rating

Question 32

What is the grid ratio if the grid frequency is 100 lines/inch, and the lead strips are 1.8 mm high and 0.3 mm apart?

A) 5:1.
B) 6:1.
C) 8:1.
D) 12:1.

Question 33

The material between the lead strips of a grid must be

A) radiopaque
B) radiolucent
C) made of lead
D) made of tungsten

Question 34

A focused grid's lead strips are angled to match

A) the anode angle
B) the angle of the x-rays in the primary beam
C) the angle of the scattered photons leaving the patient
D) the tube angulation

Question 35

The recommended SIDs that can be used with a focused grid is the

A) convergent line
B) focal distance
C) convergent point
D) focal range

Question 36

The type of grid that is usually taped to the front of an IR is the

A) wafer grid
B) bucky
C) grid cap
D) grid cassette

Question 37

Linear grids are the most commonly used because

A) they are very inexpensive
B) the tube can be angled in all directions
C) the tube can be angled in the direction of the lead lines
D) all of these

Question 38

An IR that has a grid permanently attached to its front surface is a

A) wafer grid
B) bucky
C) grid cap
D) grid cassette

Question 39

The purpose of automatic collimation is

A) improved image quality
B) limiting patient exposure
C) increasing the cost of equipment
D) none of these

Question 40

The relationship between the height of the lead strips and the distance between them is the grid

A) number
B) ratio
C) frequency
D) rating

Question 41

The grid is part of a device located just below the tabletop that also includes a tray to hold the IR. This device is the

A) wafer grid
B) bucky
C) grid cap
D) grid cassette

Question 42

The formula to use when changing from one grid to another is

A) mAs1/mAs2 = GCF2/GCF1
B) mAs1/mAs2 = (GCF2)2/GCF1)2
C) mAs1/mAs2 = GCF1/GCF2
D) mAs1/mAs2 = (GCF1)2/GCF2)2

Question 43

The cutoff that appears as a strip of appropriate exposure in the middle of the image and a significant loss of exposure on both sides is

A) upside-down focused
B) off-level
C) off-center
D) off-focus

Question 44

If a tabletop exposure (no grid) of a humerus requires 2.5 mAs, how much mAs is needed if a 12:1 ratio grid is added?

A) 0.21 mAs.
B) 0.5 mAs.
C) 12.5 mAs.
D) 30 mAs.

Question 45

The Moiré effect is also known as the _________ pattern.

A) cheetah
B) giraffe
C) lion
D) zebra

Question 46

If 22 mAs and a 5:1 grid results in an excellent radiographic image, how much mAs is needed with a 12:1 grid?

A) 8.8 mAs.
B) 9.2 mAs.
C) 52.8 mAs.
D) 55 mAs.

Question 47

If a shoulder examination is done using an 8:1 ratio grid and 12 mAs, how much mAs should be used if the examination must be done tabletop (no grid)?

A) 1.5 mAs.
B) 3 mAs.
C) 48 mAs.
D) 96 mAs.

Question 48

The type of grid that is permanently mounted but includes a channel for the IR to slide into is the

A) wafer grid
B) bucky
C) grid cap
D) grid cassette

Question 49

The formula for the grid conversion factor is

A) GCF = mAs without grid/mAs with grid
B) GCF = mAs with grid - mAs without grid
C) GCF = mAs with grid/mAs without grid
D) GCF = mAs without grid - mAs with grid

Question 50

If 24 mAs and a 6:1 grid results in an excellent radiographic image, how much mAs is needed with a 5:1 grid?

A) 16 mAs.
B) 20 mAs.
C) 28.8 mAs.
D) 36 mAs.

Question 51

To determine the amount of mAs to be increased when making grid changes, it is necessary to use the GCF, also known as the

A) grid constancy figure
B) grid compensatory factor
C) general compensation factuals
D) grid conversion factor

Question 52

Grid cutoff results in

A) reduced exposure to the IR
B) may increased patient exposure
C) possible increased in quantum noise
D) all of these

Question 53

To compensate for the reduction of radiation reaching the IR when a grid is used, ___________ is typically increased.

A) SID
B) kVp
C) mAs
D) OID

Question 54

Absorption of transmitted photons by a grid caused by misalignment is

A) grid focus
B) grid reduction
C) grid cutoff
D) transmission reduction

Question 55

During the exposure, the grid in the bucky

A) reciprocates
B) moves slightly from side to side
C) moves slightly from top to bottom
D) reciprocates and moves slightly from side to side

Question 56

When the x-ray beam is not lined up with the center of the grid you have _________ cutoff.

A) upside-down focused
B) off-level
C) off-center
D) off-focus

Question 57

When the x-ray beam is angled across the lead strips you have _________ cutoff.

A) upside-down focused
B) off-level
C) off-center
D) off-focus

Question 58

The reason the grid in the bucky reciprocates is to

A) absorb more scatter radiation
B) allow more transmitted radiation to reach the IR
C) blur out the grid lines
D) all of these

Question 59

When the SID is above or below the focal range you have _________ cutoff.

A) upside-down focused
B) off-level
C) off-center
D) off-focus

Question 60

A short-dimension grid

A) is typically used for most examinations
B) has lead strips running perpendicular to the long axis of the grid
C) has lead strips running parallel to the long axis of the grid
D) is typically used for most examinations and has lead strips running perpendicular to the long axis of the grid

Question 61

Scatter radiation is of no value in radiographic imaging.

Question 62

The air gap technique reduces the amount of scatter radiation reaching the IR because

A) more scatter is absorbed in the air
B) less scatter is produced in the patient
C) more scatter misses the IR
D) less scatter misses the IR

Question 63

Which of the following grids provides excellent scatter clean-up but requires close to perfect alignment to avoid cutoff?

A) 5:1 ratio grid.
B) 8:1 ratio grid.
C) 12:1 ratio grid.
D) 16:1 ratio grid.

Question 64

When using automatic collimation, collimating to the anatomy of interest is an unnecessary waste of time; the beam is already collimated.

Question 65

Adding a grid or increasing grid ratio results in an increase in patient dose.

Question 66

The air gap technique is based on creating a gap by increasing the ______

A) SID
B) SOD
C) OID
D) mAs

Question 67

Anyone in the room during an exposure must wear a lead apron to absorb the scatter radiation produced in the

A) table
B) patient
C) air
D) beam

Question 68

The only grid cutoff error that can occur with a parallel grid is

A) upside-down focused
B) off-level
C) off-center
D) off-focus

Question 69

The Moiré effect can be caused by

A) using a grid with a frequency similar to the CR laser scanning frequency
B) using a focused grid upside down in the bucky
C) using a grid cassette in the bucky
D) using a grid with a frequency similar to the CR laser scanning frequency and using a grid cassette in the bucky

Question 70

Focused grids are more effective than parallel grids in absorbing scatter radiation and allowing transmitted radiation to reach the IR.

Question 71

It is safe to assume that the x-ray beam field size and the light field size are exactly the same.

Question 72

To compensate for some of the loss of spatial resolution due to the large OID used with the air gap technique, the ________ should be increased as well.

A) grid ratio
B) SID
C) focal spot size
D) grid ratio and SID

Question 73

Which of the following factors need to be considered when determining the grid to be used for a specific examination?

A) Patient exposure.
B) Level of contrast improvement needed.
C) Focal range.
D) All of these.

Question 74

The grid limits the amount of scatter radiation produced in the patient.

Question 75

To overcome the decrease in sharpness caused by the air gap technique, an increase in SID is required.

Question 76

Beam-restricting devices are located just above the tube housing.

Question 77

Grids absorb almost all of the scatter radiation and allow all of the transmitted photons to pass through to the IR.

Question 78

The grid used for the air gap technique should be high frequency.

Question 79

For a lateral lumbar spine, placing a lead shield on the table behind the area of exposure

A) reduces the scatter exiting the patient
B) reduces the scatter reaching the IR
C) increases the scatter reaching the IR
D) reduces the scatter exiting the patient and reduces the scatter reaching the IR