Exposures ch 10 quiz
Which of these is the purpose of the grid?1) absorb scattered radiation2) allow scattered radiation to pass through it3) allow primary radiation to pass through it4) absorb primary radiation 1 and 2 3 and 4 2 and 4 1 and 3
1 and 3
In order to select a grid with the proper ratio, which of the following factors should be considered?1) Positioning latitude2) Degree of cleanup3) Kilovoltage range 1 only 2 only 3 only 1, 2 and 3
1, 2, 3
The reduction of scatter radiation reaching the image receptor can be accomplished by using:1) an increased OID2) Radiographic grids3) Beam limiting devices 1 &2 only 1 & 3 only 2 & 3 only 1, 2 & 3
1, 2, 3
Which of these statements is true about scattered radiation?1) Scattered radiation has less energy than primary radiation.2) Scattered radiation is produced in the x-ray tube.3) Scattered radiation puts additional energy on the image receptor.4) Scattered radiation travels in a different direction from primary radiation.5) Scattered radiation increases radiographic contrast. 1 and 3 1, 2 and 4 1, 3 and 4 2, 4 and 5
1, 3, 4
A grid should be used if the body part measures more than: 80 cm 50 cm 30 cm 10 cm
10 cm
Grids are typically only used when the part measures more than ________ cm and ______ kVp is needed for the examination. 5; 50 10; 50 10; 60 15; 65
10, 60
A technologist acquires an x-ray of the pelvis using 100 kilovoltage peak (kVp), 10 milliampere-seconds (mAs), 40 inches source-to-image distance (SID), and a no grid. The exposure level is good, but the contrast is too low. If the exam is repeated using a 16:1 grid, what new technique should be employed? 85 kVp and 60 mAs 85 kVp and 15 mAs 100 kVp and 60 mAs 100 kVp and 15 mAs
100 kVp and 60 mAs
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? 0.21 mAs 0.5 mAs 12.5 mAs 30 mAs
12.5
Which of these grids will result in the highest contrast enhancement in a radiographic image? 8:1 10:1 12:1 6:1
12:1
Which one of these grid ratios will absorb the most scattered radiation? 5:1 6:1 8:1 12:1
12:1
An effective method for reducing scatter radiation production is the 15% rule of kVp change. use of x-ray beam angulation. use of an increased exposure time with mA compensation. selection of small focal spot.
15% rule of kVp change
Which grid would most effectively reduce scatter? 6:1 8:1 12:1 15:1
15:1
What grid type requires the largest increase in milliamperage (mA) in order to maintain an appropriate receptor exposure? 8:1 10:1 12:1 16:1
16:1
Which of the following grids provides excellent scatter clean-up but requires close to perfect alignment to avoid cutoff? 5:1 ratio grid 8:1 ratio grid 12:1 ratio grid 16:1 ratio grid
16:1
When grids are utilized, the technical factors must be adjusted to maintain the IR exposure because:1) The amount of scatter produced in the patient decreases.2) The amount of scatter reaching the image receptor decreases.3) The SID must be increased. 1 only 2 only 3 only 1, 2 and 3
2 only
Calculate the new mAs if 7 mAs was originally used with a 16:1 grid and the repeated radiograph will use a 5:1 grid. 33.3 mAs 2.3 mAs 80 mAs 7.5 mAs
2.3
Calculate the new mAs if 12 mAs was originally used with a 12:1 grid and the repeated radiograph will not use a grid. 33.3 mAs 2.4 mAs 80 mAs 7.5 mAs
2.4
A radiograph of the abdomen is produced using 100 kilovoltage peak (kVp), 10 milliampere-seconds (mAs), 60 inch source-to-image distance (SID), and no grid. If the examination is repeated with a 5:1 grid, what new mAs should be used to maintain the same exposure index? 20 mAs 30 mAs 40 mAs 50 mAs
20 mAs
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)? 1.5 mAs 3 mAs 48 mAs 96 mAs
3
Which of the following combination of factors is most likely to be associated with a radiographic image possessing the highest radiographic contrast? 300 mA, 30 msec, 68 kVp, 12:1 grid ratio 400 mA, 25 msec, 87 kVp, 8:1 grid ratio 200 mA, 50 msec, 84 kVp, 10:1 grid ratio 600 mA, 15 msec, 98 kVp, 12:1 grid ratio
300 mA, 30 msec, 68 kVp, 12:1 grid ratio
Calculate the new mAs if 20 mAs was originally used with a 6:1 grid and the repeated radiograph will use a 12:1 grid. 33.3 mAs 2.3 mAs 80 mAs 7.5 mAs
33.3 mAs
A patient has been brought to the imaging department for a radiograph of his knee. Previously, the patient had a portable knee exam completed in the emergency department, using 70 kilovoltage (kV), 2.5 milliampere-seconds (mAs), and a 6:1 grid. In the x-ray room, the exposure will be completed with the image receptor in the Bucky tray with a 12:1 grid. What new mAs will be required for the exposure in the department to compensate for the higher ratio grid? 1.5 mAs 4.16 mAs 7.5 mAs 12.6 mAs
4.16 mAs
Which of the following combination of factors is most likely to be associated with a radiographic image possessing the lowest radiographic contrast? 200 mA, 25 msec, 86 kVp, 16:1 grid ratio 200 mA, 20 msec, 94 kVp, 12:1 grid ratio 400 mA, 10 msec, 102 kVp, 8:1 grid ratio 300 mA, 10 msec, 64 kVp, 8:1 grid ratio
400 mA, 10 msec, 102 kVp, 8:1 grid ratio
If 22 mAs and a 5:1 grid results in an excellent radiograph, how much mAs is needed with a 12:1 grid? 8.8 mAs 9.2 mAs 52.8 mAs 55 mAs
55
The minimum kVp that requires use of a grid is: 50 60 70 80
60 kVp
Question 141 / 1 pts Which grid would have the greatest distance between lead strips? 15:1 12:1 8:1 6:1
6:1
Which of the following focused grids will allow for the greatest amount of centering and distance lattitude: 6:1 ratio 8:1 ratio 12:1 ratio 16:1 ratio
6:1
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? 5:1 6:1 8:1 12:1
6:1 1.8/0.3
A grid that has lead strips with a height of 4 mm that are spaced 0.5 mm apart will have a grid ratio of: 2:1 4:1 8:1 16:1
8:1
A kVp above 90 requires at least a ratio of: 5:1 6:1 8:1 12:1
8:1
What is the ratio of a grid that has a grid strip thickness of 4 mm, a grid interspace thickness of 20 mm and a height of 160 mm? 5:1 6:1 8:1 16:1
8:1
Which kVp selection would result in the most scattered x-rays in the image-forming beam? 90 kVp 75 kVp 60 kVp 50 kVp
90 kvp
During the exposure, the grid in the bucky: reciprocates moves slightly from side to side moves slightly from top to bottom A and B
A and B
A grid with lead strips that run parallel to each other is a: parallel grid focused grid nonfocused grid A and C
A and C
Restriction of the primary beam to the anatomy of interest: reduces patient exposure is a major cause of repeated images reduces the amount of scatter produced A and C
A and C
A linear grid: has lead strips that cross each other has lead strips that travel in one direction is the most common type of radiographic grid B and C
B and C
A patient arrives at the imaging department on a stretcher for a shoulder exam. The technologist decides to complete the exam while leaving the patient on the stretcher without the use of a grid. However, the technologist fails to adjust the mAs that is typically used for a shoulder exam with a grid. This will result in an image that will: Have higher contrast than typical shoulder images Have decreased recorded detail than typical shoulder images Be underexposed compared to typical shoulder images Be overexposed as compared to typical shoulder images
Be overexposed as compared to typical shoulder images
The man most often credited with the construction of the first practical radiographic grid is: W. K. Roentgen H. Potter G. Bucky J. P. Focus
G Bucky
What is the main advantage of the use of a moving grid over a stationary grid? Grid lines will be more visible with a moving grid Grid lines will be blurred and not visible with a moving grid A moving grid is more efficient at absorbing scatter radiation A moving grid will produce higher contrast images
Grid lines will be blurred and not visible with a moving grid
Which of the following statements are true concerning a higher ratio grid compared to a lower ratio grid? (Select all that apply) High ratio grids absorb less scatter radiation High ratio grids demonstrate increased efficiency (contrast improvement) High ratio grids require increased milliampere-seconds (mAs) to maintain receptor exposure
High ratio grids demonstrate increased efficiency (contrast improvement) High ratio grids require increased milliampere-seconds (mAs) to maintain receptor exposure
Which of the following statements best describes a focused grid? Lead strips are angled to match the divergence of the x-ray beam Lead strips are perpendicular to each other Two sets of lead strips are present at 90 degrees to each other Lead strips are closer together in focused grids
Lead strips are angled to match the divergence of the x-ray beam
The air gap technique is based on creating a gap by increasing the ______. SID SOD OID all of the above
OID
All of the following are true of positive beam limitation (PBL) EXCEPT: PBL automatically collimates the beam. PBL senses the size and orientation of the receptor. PBL is possible with portable radiography. PBL may be overridden by the radiographer in select instances.
PBL is possible with portable radiography.
2. A device that moves the grid during a radiographic exposure is called a short-axis grid. stationary grid. Potter-Bucky diaphragm. focussed grid.
Potter-Bucky diaphragm.
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. grid ratio SID focal spot size A and B
SID
When a focused grid is used, the appearance of grid cutoff is NOT assocated with which of the following: Tube angluations directed along the grid strips A central ray that is directed to the side of the grid The use of the wrong SID The excessive tilting of the grid to the tube
Tube angluations directed along the grid strips
Which two of the following situations will result in grid cut-off? (Select two) Upside down non-focused grid Upside down focused grid Incorrect source-to-image distance (SID) with a focused grid Incorrect object-to-image distance (OID) with a focused grid
Upside down focused grid Incorrect source-to-image distance (SID) with a focused grid
The use of high ratio grids are most often recommended when: A high kilovoltage technique must be employed A number of different source-to-image distances need to be employed The dose reduction to the patient is of great concern A considerable degree of off-centering may be required.
a high kvp technique must be employed
The main advantage of a moving grid compared to a stationary grid of the same ratio and frequency is: The ability to reduce the appearance of the grid lines The ability to reduce the amount of grid cutoff The ability to employ larger tube angulations
ability to reduce appearance of grid lines
1. increased OID
air gap technique
As kVp increases, contrast decreases. scatter increases. image receptor exposure increases. all of the above
all of the above
Contrast resolution is improved by _____________. tight collimation lowering kVp patient compression All of the above
all of the above
Grid cutoff results in: reduced exposure to the IR a light film-screen image possible quantum mottle all of the above
all of the above
The radiopaque strips absorb scatter. are made of dense material. have a high atomic number. all of the above
all of the above
The use of a radiographic grid requires attention to central ray angulation. an awareness of the SID. an increase in exposure factors. all of the above
all of the above
The volume of tissue irradiated is determined by: the area of collimation patient thickness field size all of the above
all of the above
When an x-ray beam passes through the body, it will pass through the body unaffected. it will be absorbed by the body. it will interact with the body and change direction. all of the above
all of the above
Which of the following factors need to be considered when determining the grid to be used for a specific examination? patient exposure level of contrast improvement needed focal range all of the above
all of the above
When imaging the pelvis, changing from 14 × 17 collimation to 8 × 10 collimation requires: an increase in kVp a decrease in kVp an increase in mAs a decrease in mAs
an increase in mAs
The flat piece of lead with a hole in it is the: aperture diaphragm collimator cone or cylinder none of the above
aperture diaphragm
The automatic collimator: automatically collimates to the anatomy of interest is required by law on all new equipment is seldom found on modern x-ray equipment automatically collimates to the IR size
automatically collimates to the IR size
All of the following are considered beam-restricting devices EXCEPT aperture diaphragm. beam filter. positive beam limitation (PBL) device. collimator.
beam filter
In order to avoid the appearance of grid lines using a moving grid, the Bucky tray motion must commence: Before the exposure begins After the exposure begins Grid movement is not necessary
before the exposure begins
The higher the grid ratio, the _____________ the scatter clean up and the _____________________ the radiographic contrast. better; higher worse; lower better; lower worse; higher
better, higher
The reason the grid in the bucky reciprocates is to: absorb more scatter radiation allow more transmitted radiation to reach the IR blur out the grid lines all of the above
blur out the grid lines
The purpose of moving the grid during the radiographic exposure is to increase radiographic density. remove unwanted contrast. blur out the radiopaque strips. activate the AEC detectors.
blur out the radiopaque strips
The use of __________ improves contrast and reduces patient dose. collimation high kVp low kVp less filtration
collimation
The most easily adjusted radiographic beam-restricting device is the: aperture diaphragm collimator cone or cylinder none of the above
collimator
As the kilovoltage increases, the percentage of x-rays that undergo ____ interactions will increase. photoelectric coherent Compton bremsstrahlun
compton
As the kilovoltage increases, the percentage of x-rays that undergo ____ interactions will increase. photoelectric coherent Compton bremsstrahlung
compton
The atomic interaction that produces scatter radiation is Bremsstrahlung. photoelectric. Compton. photodisintegration.
compton
The use of a compression device will increase __________. film fog patient dose contrast scatter
contrast
For a grid to be properly focused, the x-ray tube must be located along the ____ line. convergence divergence umbra penumbra
convergence
The distance at which a focused grid can be used is most closely related to the: grid ratio grid frequency convergence line interspacing material
convergence line
Which one of these grid patterns is the most restrictive for angling the central ray? focused grid parallel grid criss-cross grid
cross cross grid
Which one of these grid patterns will clean up the most scattered radiation? focused grid parallel grid criss-cross grid
crossed grid
What is the advantage of a focused grid as compared to a non-focused grid? Decreased grid cut-off Increased image contrast Increased recorded detail Decreased distortion
decreased grid cut off
____________________ collimation means _________________ field size. decreasing; increasing increasing; increasing decreasing; decreasing none of the above
decreasing, increasing
The collimation assembly of a radiographic unit employs an upper and lower set of shutter blades. allows the radiographer to adjust the field size in a circular dimension. removes the mirror assembly for exposures. all of the above
employs an upper and lower set of shutter blades
Scatter radiation increases as ___________________ increases. photoelectric absorption field size filtration contrast
field size
The volume of the irradiated tissue increases as field size and patient thickness increase. patient density increases. patient orientation to the beam changes. tissue composition increases.
field size and patient thickness increase
The recommended SIDs that can be used with a focused grid is the: convergent line focal distance convergent point focal range
focal range
A type of grid in which the grid lines are situated parallel to the divergent rays of the x-ray beam is termed a: Stationary grid Focused grid Linear grid Parallel grid
focused grid
The amount of primary beam cutoff by grids can be greatly reduced by employing a: Crossed grid Focused grid Linear grid Moving grid
focused grid
The most common type of grid pattern is the: focused grid parallel grid criss-cross grid
focused grid
Which type of grid pattern will result in a radiograph with the least amount of primary beam cutoff? Focused grid Parallel grid Crossed grid Rhombic grid
focused grid
The number of lead lines per inch or centimeter is the grid: number ratio frequency rating
frequency
Absorption of transmitted photons by a grid caused by misalignment is: grid focus grid reduction grid cutoff transmission reduction
grid cut off
Angulation across the long axis of a linear grid causes grid shadowing. cross-hatched impressions. grid cut-off. grid convergence.
grid cut off
Unwanted absorption of primary radiation by the grid is the definition of: grid ratio grid focusing distance grid frequency grid cut-off
grid cut off
The ability of a grid to absorb scattered radiation after it exits from the patient is termed the: Contrast improvement factor Grid efficiency Grid uniformity Grid sensitivity
grid efficiency
Grid ratio is represented by the formula: r = h x D r = 254/D + d r = h/D r = D/h
h/D
A short-dimension grid: is typically used for most examinations has lead strips running perpendicular to the long axis of the grid has lead strips running parallel to the long axis of the grid A and B
has lead strips running perpendicular to the long axis of the grid
Which of the following is the formula used to determine grid ratio? Grid ratio = distance between the lead strips / height of the lead strips Grid ratio = width of the lead strips / height of the lead strips Grid ratio = height of the lead strips / distance between the lead strips Grid ratio = height of the lead strips / width of the lead strips
height of the lead strips / distance between the lead strips
Which of the following produces the greatest amount of scatter radiation exiting the patient? low kVp and small field size low kVp and large field size high kVp and small field size high kVp and large field size
high kvp and large field size
The ____ the atomic number of the irradiated material, the ____ the number of photoelectric absorption interactions that occur. higher; lower higher; higher lower; higher lower; unaffected
higher, higher
The ____ the atomic number of the irradiated material, the ____ the number of photoelectric absorption interactions will be, and the ____ the scatter produced. higher; lower; less higher; higher; less lower; higher; more lower; lower; less
higher, higher, less
The positive beam limiting device (PBL) assures that the x-ray beam is collimated to __________________. the exact part size 1 cm inside image receptor size the image receptor size 1 cm outside image receptor size
image receptor size
In this radiographic image, the decreased optical density seen in the lateral portion of the image most likely resulted from a/an: Excessive collimation Improper centering Excessive Bucky movement Upside down grid
improper centering
The main advantage involved with the use of a radiographic grid is: Improved radiographic contrast of the image Reduced exposure to the patient Reduced amount of scatter production in the patient An increased beam intensity
improved radiorgaphci contrast of the image
Which grid error results in grid cut-off and loss of exposure on the outside edges of the image receptor (IR)? Upside down non-focused grid Incorrect angulation of the beam across lead strips Off-level, or tilted grid error Incorrect source-to-image distance (SID) with a focused grid
incorrect SID with a focused grid
When a beam-restricting device is used to limit field size, technical factors may need to ____ to compensate for the change in image receptor exposure. be increased be decreased remain unchanged none of the above
increased
Decreasing collimation (opening up the field size) results in: increased scatter production and higher contrast increased scatter production and lower contrast decreased scatter production and higher contrast decreased scatter production and lower contrast
increased scatter production and lower contrast
As the volume of irradiated tissue ____, the amount of scatter produced ____. increases; increases increases; decreases decreases; increases decreases; decreases
increases, increases
Lowering kVp ________ patient dose and _________ image contrast. lowers, decreases increases, decreases lowers, increases increases, increases
increases, increases
A radiograph is produced in a table Bucky. The tube was properly centered to the image receptor in the Bucky tray, yet grid lines were seen. A probable cause is: Excessive grid speed Insufficient grid speed Insufficient collimation
insufficient grid speed
The spaces between the lead strips of a grid are called: interspaces gaps lucencies grid lines
interspaces
The three primary factors influencing the intensity of scatter in the image-forming beam are ___________________. mAs, kVp, and collimation mAs, filtration, and grids kVp, field size, and patient thickness filtration, patient thickness, and mAs
kVp, field size, and patient thickness
A key factor that affects the amount of scatter produced is kilovoltage. milliamperage. time. anode composition.
kilovoltage
Photoelectric interactions increase when ___________ is decreased. mAs patient thickness filtration kVp
kvp
In a modern 8:1 focused grid, the majority of scatter reduction results from the: Lead grid strips Aluminum grid strips Lead interspacing material Aluminum interspacing material
lead grid strips
The purpose of automatic collimation is: improved image quality limiting patient exposure increasing the cost of equipment none of the above
limits patient exposure
When the lead strips run in a single direction in a grid, the grid pattern is described as criss-cross. linear. cross-hatched. unparallel.
linear
A grid that is constructed with all the grid strips running parallel to each other is an exampl of a: Linear focused grid Linear parallel grid Rhombic grid Cross-hatched grid
linear parallel grid
A radiographic image that has excessive fogging due to scatter radiation would be described as: High contrast Low contrast High spatial resolution Low spatial resolution
low contrast
To compensate for the reduction of radiation reaching the IR when a grid is used, ___________ is typically increased. SID kVp mAs OID
mAs
When collimating down from a 14"x17" field size to a 8"x10" field size,: mAs must be increased to maintain IR exposure. kVp must be increased to maintain image quality. off-focus radiation production is increased. the mAs should be reduced by 50%.
mAs must be increased to maintain IR exposure.
Which situation is most likely to result in grid errors? Stationary radiography at the upright bucky Tabletop radiography Stationary radiography at the table bucky Mobile radiography
mobile radiography
The air gap technique reduces the amount of scatter radiation reaching the IR because: more scatter is absorbed in the air less scatter is produced in the patient more scatter misses the IR less scatter misses the IR
more scatter misses the IR
The principle function of the Potter-Bucky diaphragm (Bucky tray) is to provide a simple means for moving the imaging device without moving the patient. The Bucky tray also serves to: Reduce the field of views Reduce the exposure to the patients Move the grid during the exposure Reduce the amount of backscattered radiation produced
move the grid during exposure
When the x-ray beam is not lined up with the center of the grid you have _________ cutoff. upside-down focused off-level off-center off-focus
off center
When the SID is above or below the focal range you have _________ cutoff. upside-down focused off-level off-center off-focus
off focus
The only grid cutoff error that can occur with a parallel grid is: upside-down focused off-level off-center off-focus
off level
Which of the following errors in grid use will have the same results as an angulation error? Upside down focused grid Off-focus, or incorrect source-to-image distance (SID), with a focused grid Off-level, or tilted, grid error Upside down non-focused grid
off level, or tilted grid error
When the grid is assembled, the grid strips are always placed: parallel to each other perpendicular to each other parallel to the center line of the grid on edge, next to one another
on edge, next to one another
The greatest source of scatter during a radiographic examination is the patient. tube. image receptor. grid.
patient
Decreasing the kVp will increase ___________. patient dose image noise Compton scatter optical density
patient dose
As the kilovoltage increases, the percentage of photons that undergo a ____ interaction will decrease. photoelectric coherent Compton characteristic
photoelectric
Photon absorption within the body occurs as the result of Compton interactions. characteristic interactions. photoelectric interactions. Bremsstrahlung interactions.
photoelectric
The x-ray interaction that contributes to the clear parts of the image is _____________. coherent scatter Compton interaction photoelectric interaction pair production
photoelectric
Which one of these maneuvers would produce grid cut-off? using an SID within the focal range angling the central ray parallel to the center line of the grid moving the central ray along the direction of the center line of the grid placing the grid so that the center line is closest to the front of the image receptor
placing the grid so that the center line is closest to the front of the image receptor
Photons that pass through the body unaffected produce scatter radiation. radiographic contrast. secondary radiation. radiographic distortion.
radiographic contrast
The relationship between the height of the lead strips and the distance between them is the grid: number ratio frequency rating
ratio
The field shape produced by a collimator is: round oval rectangular all of the above
rectangular
When there is significant collimation, the amount of radiation reaching the IR is: reduced increased the same none of the above
reduced
What is the primary advantage of using a grid for a radiographic procedure? Reduced scatter production Increased recorded detail Decreased scatter reaching the image receptor Decreased image contrast
reduced scatter production
Penumbra is ____ when the field size is ____ . reduced; increased reduced; decreased unchanged; increased increased; unchanged
reduced, decreased
For a lateral lumbar spine, placing a lead shield on the table behind the area of exposure: reduces the scatter exiting the patient reduces the scatter reaching the IR A and B none of the above
reduces the scatter reaching the IR
The unrestricted primary x-ray beam is: round oval square rectangular
round
A grid absorbs light. incident electrons. scatter electrons. scatter radiation.
scatter radiation
A grid absorbs light. incident electrons. scatter electrons. scatter radiation. PreviousNext
scatter radiation
A focused grid's lead strips are angled to match: the anode angle the angle of the x-rays in the primary beam the angle of the scattered photons leaving the patient the tube angulation
the angle of the x-rays in the primary beam
The probability of a Compton interaction occurring is related to: the energy of the x-ray photon the atomic number of the matter the mAs used all of the above
the atomic number of the matter
A factor that affects the amount of scatter produced is the irradiated material. milliamperage. time. anode composition.
the irradiated material
When using a radiographic grid with computed radiography (CR), the Moire effect is a consideration. higher frequency grids are undesirable. radiographic grids are unnecessary. none of the above
the moire effect is a consideration
Linear grids are the most commonly used because: they are very inexpensive the tube can be angled in all directions the tube can be angled in the direction of the lead lines all of the above
the tube can be angled in the direction of the lead lines
The purpose of moving the grid with the Bucky is: to image the grid lines to blur the grid lines so the grid will be captured to change the grid rati
to blur the grid lines
The purpose of moving the grid with the Bucky is: to image the grid lines to blur the grid lines so the grid will be captured to change the grid ratio
to blur the grid lines
What is the main effect of grid cut-off? Underexposure of the image receptor Overexposure of the image receptor Decreased image contrast Decreased image spatial resolution
underexposure of the IR
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: upside-down focused off-level off-center off-focus
upside down focused
How can you improve image contrast with a heavy patient without increasing patient dose? Lower kVp and raise mAs. Use tight collimation. Raise kVp and lower mAs. Do both A and B.
use tight collimation
The x-rays that are transmitted through the patient without interaction contribute to ______________. useful information film fog image noise All of the above
useful information
Which one of these manuevers would produce grid cut-off? using an SID below the focal range angling the central ray in the direction of the center line of the grid moving the central ray along the direction of the center line of the grid placing the grid so that the center line points toward the x-ray tube
using an SID below the focal range
The most commonly used beam restricting device is the ____________. extension cone variable collimator aperture diaphragm compression device
variable collimator
Placing a lead blocker adjacent to an obese patient's anatomy during a lateral lumbar spine radiograph is unnecessary with today's digital receptors. will improve image quality. will reduce exposure to the patient. will reduce exposure to the radiographer.
will improve image quality.
