ARRT Definitions

Question 1

digital radiography-

Answer 1

includes both computed & direct radiography

Question 2

Computed Radiography-

Answer 2

-use storage phosphors to temporarily store energy representing the image signal
-phosphor then undergoes a process to extract the latent image

Question 3

direct radiography-

Answer 3

have detectors that directly capture and readout an electronic image signal.

Question 4

spatial resolution-

Answer 4

sharpness of the structural edges recorded in the image

Question 5

receptor exposure-

Answer 5

amount of radiation striking the image receptor.

Question 6

brightness-

Answer 6

measurement of the luminance of an area in a radiographic image displayed on a monitor

Question 7

contrast-

Answer 7

visible difference between any two selected areas of brightness levels within the displayed radiographic image

Question 8

grayscale-

Answer 8

refers to the number of brightness levels (or gray shades) visible on an image and is linked to the bit depth of the system

Question 9

long scale-

Answer 9

slight differences between gray shades are present (low contrast) but the total number of gray shades is great

Question 10

short scale-

Answer 10

considerable or major differences between gray shades are present (high contrast) but the total number of gray shades is small.

Question 11

dynamic range-

Answer 11

range of exposures that may be captured by a detector.

Question 12

receptor contrast-

Answer 12

fixed characteristic of the receptor.

Question 13

exposure latitude-

Answer 13

range of exposures which produces quality images at appropriate patient dose.

Question 14

subject contrast-

Answer 14

magnitude of the signal difference in the remnant beam as a result of the different absorption characteristics of the tissues and structures making up that part.

Question 15

Contrast resolution-

Answer 15

the smallest exposure change or signal difference that can be detected