Physics chapter 26
Which rule is used as a guide to maintain the same receptor exposure, when kVp changes?
15% rule
The minimum change necessary to improve the appearance of noise on a digital image is ____ percent of mAs.
25-35
The anode heel effect is more pronounced with:
A 10 degree target angle
Which statement is TRUE? -As mAs increases, scatter decreases. -As mAs decreases, quantum noise can appear. -As mAs increases, remnant radiation decreases. -As mAs decreases, exposure increases logarithmically.
As mAs decreases, quantum noise can appear
What conclusion can you reach regarding an image with an S# of 750 and good image brightness on the display monitor?
The image is likely to demonstrate noise or quantum mottle
In the case of film radiography,:
The response to exposure is logarithmic
The brightness of the image on a viewing monitor is:
a function of the monitor
Which generator produces the greatest amount of receptor exposure per mAs?
a high-frequency generator
A change in kVp, as an exposure factor, affects: -average beam energy. -beam intensity. -the amount of scatter production. -all of the above.
all of the above
Optimum exposure to a digital detector system: -varies between manufacturers. -is a function of acceptable noise levels. -is identified with target exposure index values. -all of the above.
all of the above
In the event of making a single exposure that is critical to the exam success, most experienced technologists will: A-use slightly less mAs than necessary to prevent overexposure. B-overexpose the IR slightly. C-provide enough exposure to create an adequate histogram or permit viewing a film with a bright light. -both b and c.
both b and c
Moderate increases in kVp with a digital receptor, will produce: A-dramatic changes in image contrast. B-a change in entrance skin exposure. C-no change in image brightness. -both b and c.
both b and c
When changing your SID from 72" to 56":
decrease your mAs by 50 percent
The effect of mAs upon IR exposure is:
directly proportional
Digital image artifacts such as vertical or horizontal lines, opaque, white lines demonstrates:
excessive exposure
Focal spot blooming occurs with:
high mA exposures
You have completed a chest radiograph using 3 mAs @ 110 kVp. The image shows obvious under penetration of the mediastinal anatomy. The professional radiographer would:
increase the kVp to 120 kVp and repeat the exposure at the same mAs
All of the following will decrease digital receptor exposure EXCEPT: -increased grid ratios. -increased beam angulation from 5 degrees to 10 degrees. -increased OID. -increased filtration.
increased beam angulation from 5 degrees to 10 degrees
The relationship between exposure and SID is:
inversely proportional to the square of the distance
Because of the "heel effect," x-ray beam intensity:
is greater under the cathode side of the tube
Which factor influences the average energy of photons reaching the IR?
kVp
The principal controlling factor of radiographic receptor exposure is:
mAs
Which factor influences the number of photons reaching the IR?
mAs
As you analyze your image, you come to the conclusion that it must have more exposure. As a general rule, you should increase:
mAs by 2x
Radiographic room A is a three-phase, six-pulse generator. Room B is a high-frequency generator. When going between these two rooms to perform examinations, what exposure modification is necessary to produce comparable exposure density?
no change is required between the two systems
The 15% rule will affect: -recorded detail. -image brightness. -distortion. -none of the above.
none of the above
The greatest factor in the production of scatter radiation is:
patient thickness
Assessment of digital radiographic image quality includes:
referencing exposure indicators values for acceptance
Which generator type produces the least amount of receptor exposure per mAs?
single-phase, 2-pulse
Image brightness on an image display monitor is controlled by:
window level
