Chapter 26-27 Exposures

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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


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