chapter 9

Question 1

accuracy of structural lines

Answer 1

sharpness

Question 2

amount of luminance of a display monitor

Answer 2

brightness

Question 3

what determines image quality

Answer 3

the visibility of anatomy and the sharpness of the image

Question 4

what can occur when the image receptor is extremely over exposed

Answer 4

saturation

Question 5

provides a numeric value indicating the level of radiation exposure

Answer 5

exposure indicator

Question 6

sets the midpoint of the range of brightness levels visible in the image

Answer 6

window level

Question 7

absorption characteristics of the anatomic tissue radiographed and the quality of the x ray gram

Answer 7

subject contrast

Question 8

what creates low subject contrast

Answer 8

tissues that attenuate the beam similarly

Question 9

difference between the x ray photons that are absorbed photoelectrically and those that penetrate through the body

Answer 9

differential absorption

Question 10

number of different shades of gray that can be stored and displayed by a computer scale

Answer 10

grayscale

Question 11

ability of the imaging system to distinguish between small objects that attenuate the x ray beam similarly

Answer 11

contrast resolution

Question 12

what determines the level of visibility of small objects having similar brightness levels or shades of gray

Answer 12

contrast resolution

Question 13

increase the number of shades of gray improves

Answer 13

contrast resolution

Question 14

the greater the pixel bit depth the _______

Answer 14

greater the number of shades of gray

Question 15

control that adjusts contrast

Answer 15

window width

Question 16

when there is a more narrow window width

Answer 16

the image has higher contrast or fewer shades of gray

Question 17

a wider window width does what

Answer 17

decreases contrast

Question 18

term used to evaluate accuracy of the anatomic structural lines

Answer 18

spatial resolution

Question 19

pixels are measured in

Answer 19

microns

Question 20

the greater the number of pixels in the matrix the ______ their size

Answer 20

smaller

Question 21

pixels per unit area

Answer 21

pixel density

Question 22

distance measure front the center of a pixel to an adjacent pixel

Answer 22

pixel pitch

Question 23

major determinant of spatial resolution is

Answer 23

pixel size and spacing

Question 24

increase pixel density and decreasing the pixel pitch does what

Answer 24

increases spat res

Question 25

decreasing pixel density and increase pixel pitch does what

Answer 25

decreases spat res

Question 26

how do you determine pixel size

Answer 26

pixel size = FOV divided by matrix size

Question 27

larger matrix size =

Answer 27

smaller pixel size

Question 28

unit of line pairs per millimeter

Answer 28

spatial frequency

Question 29

measure if the imaging systems absolute ability to display the contrast of anatomic objects varying in size

Answer 29

MTF

Question 30

MTF no difference in brightness levels

Answer 30

0

Question 31

MTF maximum difference in brightness levels

Answer 31

1

Question 32

MTF FORMULA

Answer 32

maximum intensity-minimum intensity divide by maximum intensity + minimum intensity

Question 33

measurement if the efficiency of an image receptor in converting the x ray exposure it receives to a quality radiographic image

Answer 33

DQE

Question 34

under control of the patient

Answer 34

voluntary motion

Question 35

size distortion or

Answer 35

magnification

Question 36

shape distortion is caused by

Answer 36

elongation or foreshortening

Question 37

visualized as brightness fluctuations on the image

Answer 37

quantum noise

Question 38

method of describing the strength of the radiation exposure compared with the amount of noise apparent in a digital image

Answer 38

SNR

Question 39

method of describing the contrast resolution compared with the amount of noise in an image

Answer 39

CNR

Question 40

tissues that attenuated the beam similarly

Answer 40

low subject contrast