Ch. 26 Physics

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) smaller field sizes (8" x 10") b) stationary anodes c) a 10* degree target angle d) rotating anodes

A 10 degree target angle

The brightness of the image on a viewing monitor is a function of the _______

A function of the monitor

Which statement is true? a. As mAs increases, scatter decreases b. As mAs decreases, quantum noise can appear c. As mAs increases, remnant radiation decreases d. As mAs decreases, exposure increases logarithmically

B. As mAs decreases, quantum noise can appear

A change in kVp, as an exposure factor, affects a. Average beam energy b. beam intensity c. the amount of scatter production d. all of the above

D. All of the above

Optimum exposure to a digital detector system A. Varies between manufacturers B. Is a function of acceptable noise levels C. Is identified with target exposure index values D. All of the above

D. All of the above

The 15% rule will affect A. Recorded detail B. Image brightness C. Distortion D. None of the above

D. None of the above

When changing your SID from 72" to 56" _______ your mAs by ________.

Decrease your mAs by 50%

Digital image artifacts such as vertical or horizontal lines, opaque, white lines demonstrates ______ exposure

Excessive exposure

Focal spot blooming occurs with a) high kVps b) high mA exposures c) large SIDs d) extreme tube angulation

High mA exposures

If 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 _______ kVp to _____ and repeat the exposure at _______ mAs.

Increase the kVp to 120 and repeat the exposure at the same mAs

All of the following will decrease digital receptor exposure except a) increased grid ratios b) increased beam angulation from 5* to 10* c) increased OID d) increased filtration

Increased beam angulation from 5° to 10°

Because of the "heel effect" X-ray beam intensity a) is greater under the cathode side of the tube b) is greater under the anode side of the tube c) is equal across the beam long axis d) changes with patient position

Is greater under the cathode side of the tube

Radiographic room A is a three phase, 6 pulse generator. Room B is a high frequency generator. When going between these two rooms to perform examinations, what exposure modifications is necessary to produce comparable exposure density?

No change is required between the two systems

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? _____ phase, ___-pulse

Single phase, 2-pulse

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 ________ or ________

The image is likely to demonstrate noise or quantum mottle

In the case of film radiography, a) the response to exposure is linear b) the response to radiation exposure is inverse c) the response to exposure is logarithmic d) the response to exposure is exclusively a function of kVp

The response to exposure is logarithmic

Which generator produces the greatest amount of receptor exposure per mAs?

a high-frequency generator

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 d) 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 D. Both b and c

both b and c

The effect of mAs upon IR exposure is a) inverse b) inversely proportional c) directly proportional d) dependent upon kVp

directly proportional

The relationship between exposure and SID is a) directly proportional b) inversely proportional to the cube of the distance c) directly proportional to the square of the distance d) inversely proportional to the square of the distance

inversely proportional to the square of the distance

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 a) kVp b) mAs by 2x c) the SID d) mAs by a 0.5 multiplier

mAs by 2x

The greatest factor in the production of scatter radiation is a) kVp b) mAs c) patient thickness d) patient position

patient thickness

Image brightness on an image display monitor is controlled by? a) window level b) window width c) EI number d) S number

window level