EXAM 3-Principles of Radiographic Imaging

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

3 mAs

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

automatically collimates to the IR size

The distance between the grid and the convergent line is the: a. convergent line b. focal distance c. convergent point d. focal range

focal distance

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

ratio

If 24 mAs and a 6:1 grid results in an excellent radiograph, how much mAs is needed with a 5:1 grid? a. 16 mAs b. 20 mAs c. 28.8 mAs d. 36 mAs

16 mAs

The purpose of automatic collimation is: a. improved image quality b. limiting patient exposure c. increasing the cost of equipment d. none of the above

limiting patient exposure

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

mAs

Beam-restricting devices are located just above the tube housing. a. true b. false

false

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

false

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

false

The air gap technique is a frequently used method for reducing the amount of scatter radiation reaching the IR. a. true b. false

false

The grid limits the amount of scatter radiation produced in the patient. a. true b. false

false

The grid used for the air gap technique should be high frequency. a. true b. false

false

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

false

Absorption of transmitted photons by a grid caused by misalignment is: a. grid focus b. grid reduction c. grid cutoff d. transmission reduction

grid cutoff

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

patient

For 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. A and B d. none of the above

reduces the scatter reaching the IR

The unrestricted primary x-ray beam is: a. round b. oval c. square d. rectangular

round

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

true

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

true

Scatter radiation is of no value in radiographic imaging. a. true b. false

true

If a table top 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

12.5 mAs

If 22 mAs and a 5:1 grid results in an excellent radiograph, how much mAs is need with a 12:1 grid? a. 8.8 mAs b. 9.2 mAs c. 52.8 mAs d. 55 mAs

55 mAs

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. A and B

A and B (reciprocates & moves slightly from side to side)

Restriction of the primary beam to the anatomy of the interest: a. reduces patient exposure b. is a major cause of repeated images c. reduces the amount of scatter produced d. A and C

A and C

A grid with lead strips that run parallel to each other is a: a. a parallel grid b. focused grid c. nonfocused grid d. A and C

A and C (a parallel grid & nonfocused grid)

The Moire' 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. A and C

A and C (using a grid with a frequency similar to the CR laser scanning frequency & using a grid cassette in the bucky)

Grids are typically only used when the part measures more than ________ cm and __________ kVp is need for the examination. a. 5; 50 b. 10; 50 c. 10;60 d. 15; 65

10; 60

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. B and C

B and C (has lead strips that travel in one direction & is the most common type of radiographic grid)

For radiographic procedures, scatter radiation is primarily the result of: a. photoelectric interaction b. pair production c. Compton interaction d. classical scattering

Compton interaction

The formula for the grid conversation 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

GCF = mAs with grid/ mAs without grid

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

Grid ratio= height of the lead strips/ distance between the lead strips

The air gap technique is based on creating a gap by increasing the ___________. a. SID b. SOD c. OID d. all of the above

OID

The exam room in our lab that offer automatic collimation is: a. Room 1 b. Room 2 c. Room 3 d. Room 4

Room 3

To compensate for some of the loss of recorded detail 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. A and B

SID

Grid cutoff results in: a. reduced exposure to the IR b. a light film-screen image c. possible quantum mottle d. all of the above

all of the above

The volume of tissue irradiated is determined by: a. the area of collimation b. patient thickness c. field size d. all of the above

all of the above

Which of the following factors needed to be considered when determine the grid to be used for a specific examination? a. patient exposure b. level of contrast improvement needed c. focal range d. all of the above

all of the above

When imaging the pelvis, changing from 14 x 17 collimation to 8 x 10 collimation requires: a. an increase in kVp b. a decrease in kVp c. an increase in mAs d. a decrease in mAs

an increase in mAs

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 the above

aperture diaphragm

The flat piece of lead with a hole in it is the: a. aperture diaphragm b. collimator c. cone or cylinder d. none of the above

aperture diaphragm

The higher the grid ratio, the ____________ the scatter clean up and the ____________ the radiographic contrast. a. better; higher b. worse; lower c. better; lower d. worse; higher

better; higher

The grid is located: a. just below the x-ray tube window b. between the patient and IR c. just below the IR d. none of the above

between the patient and IR

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 the above

blur out the grid lines

The grid is part of a device located just below the tabletop that also includes a tray to hold the IR. The device is the: a. wafer grid b. bucky c. grid cap d. grid cassette

bucky

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 the above

collimator

The most effective and often used radiographic beam-restriction device is the: a. aperture diaphragm b. collimator c. cone or cylinder d. none of the above

collimator

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 the above

cone or cylinder

If all the convergent points were connected along the length of the grid they would from the: a. convergent line b. focal distance c. convergent point d. focal range

convergent line

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

convergent point

Beam restriction serves which two main purposes: a. decrease patient dose and decrease scatter b. decrease patient dose and increase scatter c. increase patient dose and decrease scatter d. increase patient dose and increase scatter

decrease patient dose and decrease scatter

____________ collimation means __________ field size. a. decreasing; increasing b. increasing; increasing c. decreasing; decreasing d. none of the above

decreasing; increasing

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

focal range

The number of lead lines per inch or centimeter is the grid: a. number b. ratio c. frequency d. rating

frequency

The type of grid that includes a channel for the IR to slide into is the: a. wafer grid b. bucky c. grid cap d. grid cassette

grid cap

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

grid cassette

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

grid conversion factor

A short-dimension grid: a. is typically used for most examinations b. has lead strips running perpendicular to the long axis c. has lead strips running parallel to the long axis of the grid d. A and B

has lead strips running perpendicular to the long axis of the grid

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

high kVp and large field size

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

mAs1/mAs2= GCF1/GCF2

The air gap technique reduces the amount of scatter radiation reaching the IR because: a. more scatter is absorbed in the patient b. less scatter is produced in the patient c. more scatter misses the IR d. less scatter misses the IR

more scatter misses the IR

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

off-center

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

off-focus

The only grid cut-off error that can occur with a parallel grid is: a. upside-down focused b. off-level c. off-center d. off-focus

off-level

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

off-level

The material between the lead strips of a grid must be: a. radiopaque b. radiolucent c. made of lead d. made of tungsten

radiolucent

When there is significant collimation, the amount of radiation reaching the IR is: a. reduced b. increased c. the same d. none of the above

reduced

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

the angle of the x-rays in the primary beam

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 the above

the energy of the x-ray photon

Linear grids are the most commonly used because: a. they are very inexpensive b. the tube can be angled in all direction c. the tube can be angled in the direction of the lead lines d. all of the above

the tube can be angled in the direction of the lead lines

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

travel at an angle to the transmitted photons

The cutoff that appears as a strip of appropriate density in the middle of the image and a significant loss of density on both sides is: a. upside-down focused b. off-level c. off-center d. off-focus

upside-down focused

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

volume of tissue irradiated and kVp

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

wafer grid

The Moire' effect is also known as the _________ pattern. a. cheetah b. giraffe c. lion d. zebra

zebra