Final exam review

Question 1

ability to distinguish between similar objects as having different shades of gray

Answer 1

contrast resolution

Question 2

exposure error still resulting in a quality image at an appropriate dose

Answer 2

exposure latitude

Question 3

how accurately a system converts x-ray input signals into a useful output image defines:

Answer 3

MTF

Question 4

how efficiently a system converts x-ray input signals into a useful output image defines:

Answer 4

DQE

Question 5

when was computed radiography introduced?

Answer 5

1981

Question 6

what are the different layers of the phosphor layer?

Answer 6

conduction band (traps electrons)
valence band (houses electrons)
phosphor layer

Question 7

what is the purpose of the reflective layer?

Answer 7

sends light toward the photodetector

Question 8

what is the purpose of the conductive layer?

Answer 8

absorbs and reduces static electricity

Question 9

what type of phosphor is typically used in computed radiography?

Answer 9

barium fluorohalide doped w/ europoum

Question 10

the second emission of light during exposure of a CR imaging plate represents:

Answer 10

electrons being released due to the red laser scanning the plate

Question 11

what is the latent image?

Answer 11

trapped electrons in the PSP

Question 12

what is the manifest image?

Answer 12

image that shows up on the computer

Question 13

list the steps needed to produce a manifest image:

Question 14

what sends an electrical signal to the ADC?

Answer 14

photodetector/photomultiplier

Question 15

what is a histogram?

Answer 15

graphical display of the pixel intensity distribution for digital image

Question 16

what is rescaling?

Answer 16

adjusts overall exposure up or down to correct exposure errors

Question 17

what is the controlling factor in producing image contrast?

Answer 17

increased contrast resolution

Question 18

how do we adjust image brightness?

Answer 18

window level

Question 19

how do we adjust image contrast?

Answer 19

window width

Question 20

what controls an imaging system’s ability to produce differing levels of contrast resolution?

Answer 20

bit depth

Question 21

what is smoothing?

Answer 21

reduction of noise

Question 22

what is equalization?

Answer 22

making underexposed areas dark and overexposed areas light

Question 23

how do we erase IPs after use?

Answer 23

flood them with white light

Question 24

how many shades of gray can a system that has a bit depth of 10 show?

Answer 24

1024

Question 25

how is spatial resolution measured?

Answer 25

line pairs/mm

Question 26

specific to DR, list three factors that contribute to spatial resolution:

these factors share a ________ relationship with spat. res.

Answer 26

speed class
phosphor layer thickness
laser diameter;

direct