RTBC-Principles of Exposure

Question 1

How is gross exposure error demonstrated in a digital image?

Answer 1

missing data points

Question 2

The smallest exposure difference that can be detected and displayed by the imaging system is called:

Answer 2

contrast resolution

Question 3

The fill factor of the direct radiography (DR) image receptor is the:

Answer 3

sensitive portion of the detector element compared to the non-sensitive portion

Question 4

Which 3 mistakes are most likely to result in a histogram error artifact?

Answer 4

using incorrect collimation, processing a posteroanterior (PA) chest radiograph as a lateral chest, and processing a knee radiograph as a chest

Question 5

Increasing the field-of-view (FOV) will have what effect on the pixel size?

Answer 5

increased pixel size

Question 6

If a radiographer produced an image using an x-ray exposure that is below the dynamic range, the resulting image is expected to display:

Answer 6

quantum mottle

Question 7

The spatial resolution of a radiography system is expressed in units of:

Answer 7

line pairs per millimeter (mm)

Question 8

The formula to determine the magnification factor is:

Answer 8

magnification factor (MF) = source-to-image distance (SID) / source-to-object distance (SOD)

Question 9

When source-to-image distance (SID) is increased, which change must be made to maintain image receptor (IR) exposure?

Answer 9

increase milliampere-seconds (mAs)

Question 10

Digital image receptors with a large detector element (DEL) pitch will have:

Answer 10

low spatial resolution

Question 11

An exposure is made using 5 milliampere-seconds (mAs) and 50 kilovoltage peak (kVp). What kVp is needed to double the exposure to the image receptor?

Answer 11

58 kVp

Question 12

An increase in tube potential would increase image receptor exposure by increasing the:

Answer 12

number of photons in the beam and the penetrating ability of the beam

Question 13

The ability to produce quality radiographs using a wide range of technical factors is called:

Answer 13

exposure latitude

Question 14

Scatter radiation does NOT affect:

Answer 14

recorded spatial resolution

Question 15

An underexposed image might produce an image artifact called:

Answer 15

noise and quantum mottle

Question 16

What effect does using a large focal spot have on spatial resolution?

Answer 16

decreases spatial resolution

Question 17

A radiographer acquires an image of the chest using 85 kilovoltage peak (kVp) and 5 milliampere-seconds (mAs). Her colleague acquires an image of the chest of the same patient using 90 kVp and 4 mAs. Both exposures resulted in an optimal image and an acceptable patient dose. This is an example of:

Answer 17

exposure latitude

Question 18

Source-to-image distance (SID) refers to the distance from the:

Answer 18

focal spot target on the x-ray tube to the image receptor

Question 19

During a series of mobile chest x-rays in the emergency room department, the technologist fails to adjust the kilovoltage peak (kVp) for a hypersthenic patient after their previous asthenic patient. This is likely to result in:

Answer 19

quantum mottle

Question 20

Within digital radiography, bit depth is defined as the:

Answer 20

total number of gray shades that can be produced by the digital system