digital equipment

Question 1

the sharpness of the structural edges recorded in the image

Answer 1

spatial resolution

Question 2

the amount of radiation striking the image receptor

Answer 2

receptor exposure

Question 3

is the measurement of the luminance of an area in a radiographic image displayed on a monitor. it is in units of candela per sq meter

Answer 3

brightness

Question 4

is the visible difference between any two selected areas of brightness levels within the displayed radiographic image. It is determined by the processing algorithm

Answer 4

contrast

Question 5

refers to the number of brightness levels visible on an image and is linked to the bit depth of the system

Answer 5

grayscale

Question 6

major differences btw gray shades are present (high contrast)

Answer 6

short scale

Question 7

slight differences btw gray shades are present ( low contrast)

Answer 7

long scale

Question 8

the range of exposures that produces quality images at appropriate patient dose

Answer 8

exposure latitude

Question 9

the 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

Answer 9

subject contrast

Question 10

uses an IP made of PSP; absorbs energy exiting the patient; IP is scanned with a laser; energy is released and converted to analog to digital for postprocessing

Answer 10

CR

Question 11

uses wired or wireless flat panel detectors that communicate directly with a computer workstation; produces an image quicker than CR

Answer 11

direct DR

Question 12

convert exit radiation first to visible light and then to electrical charges; uses CCD

Answer 12

DR indirect

Question 13

convert exit radiation directly into electrical charges, speeding image construction

Answer 13

DR direct

Question 14

composed of rows and columns called matrix

Answer 14

digital image

Question 15

picture element; smaller part of a digital image; is a shade of gray representing voxel

Answer 15

pixel

Question 16

number of pixels/mm in the image; determined by pixel pitch

Answer 16

pixel density

Question 17

volume element; an area of tissue in the patient

Answer 17

voxel

Question 18

adjusts the image brightness throughout the range of density

Answer 18

window level

Question 19

adjusts the image contrast

Answer 19

window width

Question 20

source of noise; caused by too few photons hitting the receptor (grainy)

Answer 20

quantom noise

Question 21

comparison of the useful signal to the presence of noise; high SNR results in a higher quality image

Answer 21

SNR (signal to noise ratio)

Question 22

low contrast =

Answer 22

high kvp

Question 23

high contrast =

Answer 23

low kvp

Question 24

used to reduce the amount of scatter radiation reaching the film

Answer 24

grids

Question 25

the height of the lead strips divided by the distance btw the lead strips

Answer 25

grid ratio

Question 26

number of lead strips per inch

Answer 26

grid frequency

Question 27

lead strips are parallel to one another

Answer 27

linear grids

Question 28

lead strips are angled to coincide with divergence of the X-ray beam

Answer 28

focused grid

Question 29

decreased density along the periphery of the film caused by absorption of image-forming rays

Answer 29

grid cut off

Question 30

distance at which focused grid may be used

Answer 30

grid radius