Chapter 18

Question 1

The primary purpose of using a radiographic grid is to
a. intercept remnant radiation.
b. remove undesired primary photons.
c. remove a percentage of scatter photons.
d. decrease skin exposure to patients.

Answer 1

remove a percentage of scatter photons

Question 2

A radiographic grid absorbs
a. primary radiation.
b. all scatter and secondary electrons.
c. scatter electrons.
d. scatter radiation.

Answer 2

scatter radiation

Question 3

When an x-ray beam passes through the body,
a. it will pass through the body unaffected.
b. it will be absorbed by the body.
c. it will interact with the body and change direction.
d. all of the above.

Answer 3

all of the above

Question 4

Photons that pass through the body unaffected produce
a. scatter radiation.
b. radiographic contrast.
c. secondary radiation.
d. radiographic distortion.

Answer 4

radiographic contrast

Question 5

Photon absorption within the body occurs as the result of
a. Compton interactions.
b. characteristic interactions.
c. photoelectric interactions.
d. Bremsstrahlung interactions.

Answer 5

photoelectric interactions

Question 6

The atomic interaction that produces scatter radiation is
a. Bremsstrahlung.
b. photoelectric.
c. Compton.
d. photodisintegration.

Answer 6

compton

Question 7

As kVp increases,
a. secondary radiation increases.
b. scatter radiation increases.
c. image receptor exposure increases.
d. all of the above.

Answer 7

all of the above

Question 8

The greatest source of scatter during a radiographic examination is the
a. patient.
b. table top material.
c. image receptor.
d. AEC detector.

Answer 8

patient

Question 9

The amount of scatter radiation produced increases with a/an
a. increase in patient thickness.
b. larger field size.
c. decrease in atomic number of the tissue.
d. all of the above.

Answer 9

all of the above

Question 10

As a general rule, a radiographic grid is employed
a. for procedures below 60 kVp.
b. for part thicknesses above 10 cm.
c. for pediatric studies to improve contrast.
d. in order to improve positioning latitude.

Answer 10

for part thickness above 10 cm

Question 11

The use of a radiographic grid requires
a. attention to central ray angulation.
b. an awareness of the SID.
c. an increase in exposure factors.
d. all of the above.

Answer 11

all of the above

Question 12

Which statement about radiographic grids is incorrect?
a. Grids may have grid strips running in perpendicular directions.
b. A grid is a series of lead strips that alternate with radiopaque interspace strips.
c. The radiopaque strips are typically made of thin lead.
d. The interspace strips are usually made of aluminum.

Answer 12

a Grid is a series of lead strips that alternate with radiopaque interspace strips

Question 13

The purpose of moving the grid during the radiographic exposure is to
a. activate the digital detector.
b. remove unwanted contrast.
c. blur out the radiopaque strips.
d. activate the AEC detectors.

Answer 13

blur out the radiopaque strips

Question 14

The radiopaque strips
a. absorb scatter.
b. are made of radiodense material.
c. have a high atomic number.
d. all of the above.

Answer 14

all of the above

Question 15

The ratio of the height of the lead strips to the distance between the lead strips is the grid
a. selectivity.
b. ratio.
c. frequency.
d. speed.

Answer 15

ratio

Question 16

Which grid would have the greatest distance between lead strips?
a. 15:1
b. 12:1
c. 8:1
d. 6:1

Answer 16

6:1

Question 17

Which grid would most effectively reduce scatter?
a. 6:1
b. 8:1
c. 12:1
d. 15:1

Answer 17

15:1

Question 18

The number of grid lines per inch is the grid
a. focus.
b. ratio.
c. frequency.
d. speed.

Answer 18

frequency

Question 19

As the lead content of a grid increases,
a. the contrast improvement factor decreases.
b. the ability of the grid to remove scatter increases.
c. the K-factor decreases.
d. exposure to the image receptor increases.

Answer 19

the ability of the grid to remove scatter increases

Question 20

When the lead strips run in a single direction in a grid, the grid pattern is described as
a. criss-cross.
b. linear.
c. cross-hatched.
d. Tangential.

Answer 20

linear

Question 21

Angulation across the long axis of a linear grid causes
a. grid shadowing.
b. cross-hatched impressions.
c. grid cut-off.
d. grid convergence.

Answer 21

grid cut off

Question 22

For a grid to be properly focused, the x-ray tube must be located along the ____ line.
a. convergence
b. divergence
c. tangent
d. resolution

Answer 22

convergence

Question 23

A device that moves the grid during a radiographic exposure is called a(n)
a. oscillator.
b. alternator.
c. Potter-Bucky diaphragm.
d. focussed grid.

Answer 23

potter-bucky diapgragm

Question 24

A Potter-Bucky diaphragm must move the grid in a direction that is ____ to the direction of the grid lines.
a. perpendicular
b. parallel
c. at a 45° angle
d. at a 37° angle

Answer 24

perpendicular

Question 25

When using a radiographic grid with computed radiography (CR),
a. the Moire effect is a consideration.
b. higher frequency grids are undesirable.
c. radiographic grids are unnecessary.
d. none of the above.

Answer 25

the moire effect is a consideration

Question 26

With digital detector technology, final image contrast is primarily due to the application of
a. very high kVp values
b. Look-Up-Tables(LUTs)
c. faster receptor speeds
d. very low kVp, high mAs exposures

Answer 26

look up tables

Question 27

Grid cut-off artifacts are a particular problem when performing radiographic exams using digital detectors. Even a small degree of cut-off can show up on the final image. This is primarily due to the
a. very small mAs exposures typically used with fast digital receptors
b. high grid ratios required with digital detectors
c. extreme sensitivity of the digital receptors, to scatter radiation
d. high kVp photons penetrating the grid strips

Answer 27

very small mAs exposures typically used with fast digital receptors

Question 28

Grid replacement software is designed to
a. hide the grid lines from the viewer
b. allow the radiographer to select a grid ratio for postprocessing
c. create a nongrid image that looks like a grid was employed
d. all of the following

Answer 28

create a nongrid image that looks like a grid was employed

Question 29

Grid suppression software is intended to
a. remove the visibility of grid lines
b. blur out the grid lines through dynamic visual motion
c. lower image contrast for the viewer, to reveal low contrast objects
d. amplify the visibility of the radiopaque grid strips

Answer 29

remove the visibility of grid lines

Question 30

In an emergency situation when a radiographic grid is unavailable, a convenient practice to employ, that creates a “grid-like image” when one was not used is
a. grid suppression software
b. to turn the digital detector over, to use the back of the detector as an absorber
c. increase the OID to create an air-gap
d. all of the above

Answer 30

increase the OID to create an air-gap