foundations unit 3 exam review

T/F

If the height of the grid were constant, decreasing the distance between the lead strips would result in an increase in the grid ratio.

true

For the same beam intensity, air produces ________ exposure intensity to the image receptor than other materials

greater

A radiographer can reduce the amount of scatter radiation reaching the IR by:

a) collimating

b) utilizing a grid

c) beam restriction

d) all of the above

d

Which grid would have the lowest grid ratio?

12:1

8:1

15:1

6:1

6:1

Which of the following elements would attenuate a greater percentage of the x-ray beam?

a) hydrogen

b) calcium

c) carbon

d) oxygen

calcium

The ____ the photon energy, the ____ the likelihood that, if an interaction occurs, the interaction will be a Compton interaction

higher; higher

As a general rule, a grid is employed when the body part thickness exceeds ____ cm

10-13

Volume of the irradiated tissue increases as

pt thickness increases

T/F

An additive disease is characterized by a decrease in bone density, tissue thickness, or normal fluid levels

false

The undesirable absorption of primary radiation by a grid is called:

grid cut-off

T/F

A focused design results in a grid with lead strips designed to match the divergence of the x-ray beam

true

The ____ the body part, the ____ the attenuation

thicker; greater

Bone produces less image receptor ____ because it attenuates the x-ray beam more than soft tissue does

exposure

T/F

As irradiated tissue volume increases, scatter increases

true

A satisfactory abdominal radiograph is produced using a 12:1 grid, 30 mAs, and 85 kVp. A second image is requested using a 16:1 grid. Provide a new technique that could be used to produce the second radiograph?

85 kVp

36 mAs

When the lead strips run in two directions perpendicular to each other in a grid, the grid pattern is described as

cross-hatched

When a patient is exposed to an x-ray beam:

a) Some photons will pass through the body unaffected

b) Some photons will be absorbed by the body

c) Some photons will interact with the body and change direction

d) all answers are correct

d

Distortion can be the misrepresentation of the ____ of an object

a) shape

b) length

c) width

d) all of the above

d

A convergence line is most closely associated with which of the following?

focused linear grid

When is a grid most likely to be needed in radiography?

when large field sizes are used

Which of the following grids would you expect to move during the exposure?

oscillating grid

If the lead strips are 2.0 mm high and are separated by an interspace of 0.25 mm, what is the grid ratio?

8:1

As the lead content of a grid increases

The ability of the grid to remove scatter increases

A satisfactory radiograph is produced using 10 mAs at 85 kVp without a grid. A second image is requested using a 16:1 grid. Provide a new technique that could be used to produce the second radiograph?

60 mAs

85 kVp

T/F

Scatter radiation can add exposure to the image receptor

true

A grid absorbs:

a) Scatter electrons

b) Scatter radiation

c) incident electrons

d)Light

b

scattered photons will:

a) Add to image receptor exposure

b) Not be considered part of the useful beam

c) Impair image quality

d) all answers are correct

d

The ratio of the height of the lead strips to the distance between the lead strips is the grid ____

ratio

With a patient in the supine position, the anatomical structure that would demonstrate the greatest subject detail (spatial resolution) would be the:

a) nasal bones

b) spinous processes

c) vertebral pedicles

d) sternum

b

Complete photon absorption within the body occurs as the result of

photoelectric interaction

If OID increases, the amount of scatter reaching the IR __________

decreases

Which grid would most effectively reduce scatter?

a) 8:1

b) 15:1

c) 12:1

d) 6:1

b

If grid ratio increases, the contrast scale ___________

shortens

T/F

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

true

Which of the following is the least attenuator of the x-ray beam?

a) aerated lung

b) perirenal fat

c) psoas muscle

d) pericardial fat

a

If patient thickness decreases, scatter production _______

decreases

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

greater exposure

A device that moves the grid during a radiographic exposure is called a

Potter-Bucky Diaphragm

Each of the following is considered a beam-restricting device except the:

a) Aperture diaphragm

b) cone

c) collimator

d) grid

d

A grid is used to improve

radiographic contrast

The primary purpose of using a radiographic grid is to

remove a percentage of scatter photons

The source of scatter generation during a radiographic examination is the

patient

If the lead strips are 4.0 mm high and are separated by an interspace of 0.25 mm, what is the grid ratio?

16:1

T/F

A radiographer can minimize the amount of scatter radiation produced and ultimately reaching the image receptor by restricting the beam

true

The number of grid lines per inch is the grid ____

frequency

what can be placed between the patient and the image receptor to absorb scatter radiation?

grid

T/F

The higher the grid ratio, the higher the grid conversion factor

true

Which statement about grids is incorrect?

a) The strips are usually made of lead

b) A grid is a series of radiopaque strips that alternate with radiolucent interspace material

c) A grid is a series of radiolucent strips that alternate with radiopaque interspace material

d) They can be classified by ratio, frequency, or lead content

c

As subject density increases_, image receptor exposure ____

decreases

With the patient in the posterior-anterior projection of the abdomen (prone):

a) he psoas muscles would have high resolution

b) renal stones would have high resolution

c) the lumbar vertebrae would have high resolution

d) the anterior ribs would have high resolution

d

T/F

Utilizing the air-gap technique will increase the amount of scatter reaching the IR

false

A satisfactory radiograph is produced using 8 mAs at 75 kVp without a grid. A second image is requested using an 8:1 grid. Provide a new technique that could be used to produce the second radiograph?

75 kVp

32 mAs

T/F

The beam emitted from the patient contains diagnostic information

true

After reviewing an image taken with no grid, you decide you will need to repeat the exposure with a grid. To maintain the same IR exposure, you should anticipate that you will need to ______ the technical factors

increase

When the lead strips run in a single direction in a grid, the grid pattern is described as

linear

As the volume of irradiated tissue increases, the amount of scatter ____

increases

A grid has the following characteristics: grid frequency = 64 lines/cm, height of strips = 4.0 mm, interspace width = 0.4 mm. What is the grid ratio?

10:1

High ratio grids remove ____ scatter than low ratio grids

more

Which set of factors will produce the least amount of scatter?

a) Low kV, thick part, 11x14 field size

b) High kV, thin part, 11x14 field size

c) Low kV, thin part, 10x12 field size

d) Low kV, thin part, 14x17 field size

c

T/F

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

true

The degree of differential absorption is referred to as

subject contrast

Which of the following is the greatest attenuator of the x-ray beam?

a) psoas muscle

b) perirenal fat

c) aerated lung

d) pericardial fat

a

Angulation across the long axis of a linear grid causes

grid cut-off

Which of the following elements is NOT commonly found in the human body?

a) helium

b) nitrogen

c) carbon

d) hydrogen

a

What term describes the grid's ability to allow primary radiation to reach the image receptor while preventing scatter?

grid selectivity