Chapter 26-27 Exposures
If a radiograph using 40 mAs (400 mA at 0.10 sec.) produced a radiograph with satisfactory density, what new time should be used at 200 mA?
0.2 sec
The optical density range visible to the human eye is:
0.25 to 2.50
If 80 kVp, 400 mA, and 0.025 sec. produce a satisfactory radiograph, what mas was used?
10 mAs
If a satisfactory density is obtained with 40 mAs at 72", what mAs is required to maintain the same density at 40"?
12 mAs
If a satisfactory radiograph is obtained at 72" with a patient exposure of 4 R, what will the exposure be if distance is reduced to 40"?
13 R
Which rule is used as a guide to maintain the same density when kVp changes:
15% rule
If a radiograph using 50 mA (400 mA at 0.125 sec.) produced a radiograph with satisfactory density, what new mA should be used at 0.24 sec.?
200 mA
The minimum change necessary to cause a visible shift in density is _______ percent of mAs.
25-35
If a satisfactory PA chest radiograph is obtained with 4 mAs at 72" what mAs is required to maintain the same density at 60"?
3 mAs
Depending upon the kVp range, a visible change in contrast will not be seen unless kVp is minimally changed:
4-12%
A radiograph of the forearm is produced using 4 mA at 55 kVp. What kVp is required to halve the exposure?
47 kVp
75 kV, 20 mAs, 40" SID. Double density and increase contrast. SID changed to 30"
64 kV 45 mAs
If a satisfactory density is obtained with 20 mAs at 40", what mAs is required to maintain the same density at 72"?
65 mAs
80 kV, 20 mAs, 40" SID. Halve density and maintain contrast.
80 kV 10 mAs
80 kV, 20 mAs, 40" SID. Maintain density and maintain contrast. SID changed to 72"
80 kV 65 mAs
75 kV, 20 mAs, 40" SID. Halve density and decrease contrast
85 kV 5 mAs
The anode heel effect is more pronounced with:
A 10 degree target angle
The brightest of the image on a viewing monitor is:
A function of the monitor
Which generator produces the greatest amount of radiographic density per mAs?
A high frequency generator
Which statement is false? As mAs increases, exposure decreases As mAs decreases, density decreases As mAs increases, density increases As mAs decreases, exposure increases
As mAs decreases, exposure increases
A change in kVp, as an exposure factor, affects:
Average beam energy Beam intensity The amount of scatter production
Used to calculate slope of the H and D curve:
Average gradient
A severely underexposed film image will:
Be unable to visualize recorded detail
Contrast affected: Decrease SID from 72" to 60"
Contrast stays the same
Contrast affected: Change kV from 70 to 80.
Decrease contrast
Contrast affected: From a small patient to a large patient
Decrease contrast
The 15% rule changes:
Density and contrast
Density affected: From 70 kV, 30 mAs to 80 kV, 15 mAs
Density stays the same
The concept of contrast as it is displayed on a soft copy monitor for digital images is described as:
Dynamic range
Contrast decreases with:
Excessive density Inadequate density A wider range of density
A radiograph that demonstrates considerable differences between densities is called:
High contrast
A radiograph with few shades of gray exhibits
High contrast
Fewer shades od gray across the final image
High contrast
When the tissue structure of the ankle joint is considered, the dramatic tissue differences between the muscles and bones of the ankle produce:
High subject contrast
Density affected: Change mAs from 25 to 50.
Increase density
Density affected: Change the kV from 70 to 80.
Increase density
The relationship between exposure and SID is:
Inversely proportional to the square of the distance
A radiograph that demonstrates minimal differences between densities is called:
Long scale Low contrast decreased contrast
The same as low contrast:
Long scale contrast
What should you expect to occur with a decrease in kVp?
More photoelectric interactions
The greatest factor in the production of scatter radiation is:
Patient thickness
Responsible for high contrast densities on images:
Photoelectric interactions
The difference between two adjacent densities is:
Radiographic contrast
Contributing factor to total image contrast
Subject contrast
The recorded detail of a radiographic image is visible because of:
Sufficient contrast and density
High contrast is directly related to:
The number of photoelectric interactions
The principal controlling factor of contrast is:
kVp
Which factor influences the average energy of photons reaching the IR?
kVp
The principal controlling factor of radiographic image density is:
mAs
Which factor influences the number of photons reaching the IR?
mAs
