week 8: image quality

Question 1

What does a quality image accurately represent?

Answer 1

(1) accurately represents the anatomic area of interest and (2) information is well visualized for diagnosis

Question 2

What two factors (2 types of resolution) determine the overall quality of the radiographic image?

Answer 2

contrast resolution, spatial resolution

Question 3

visibility of detail

Answer 3

contrast resolution

Question 4

sharpness of detail

Answer 4

spatial resolution

Question 5

image density (optical density or OD): the ____________ represent the ___________ properties of the anatomic part imaged

Answer 5

varying optical densities, attenuation

Question 6

amount of luminance (light emission) of a display monitor

Answer 6

image brightness

Question 7

____________ are geometric qualities

Answer 7

Detail and distortion

Question 8

___________ are photographic qualities

Answer 8

optical density and contrast

Question 9

spatial resolution is used to evaluate the accuracy of the _____________________

Answer 9

anatomic structural lines displayed

Question 10

high contrast images display _________________ but ____________

Answer 10

fewer shades of gray but greater differences among them

Question 11

low contrast images display ________________ but _____________

Answer 11

greater number of gray shades but smaller differences among them

Question 12

clear area of the image = ___ optical density

Answer 12

low

Question 13

black area of the image = ____ optical density

Answer 13

high

Question 14

with digital images, ________ is now the name for optical density

Answer 14

brightness

Question 15

what is another definition for film densities (Bontrager)?

Answer 15

defined as the amount of “blackness” on the processed radiograph

Question 16

clear area of the image = ________ brightness

Answer 16

increased

Question 17

black area of the image = ________ brightness

Answer 17

decreased

Question 18

optical density and brightness result from the ________ of radiation reaching a particular area

Answer 18

quantity

Question 19

What is the primary technical factor that controls the amount of OD in an analog image (film/screen image)?

Answer 19

mAs; controls the quantity the reaches the film AND how the manifest image looks

Question 20

What is the primary factor that controls the amount of OD in a digital image?

Answer 20

mAs; controls quantity that reaches the IR however the computer algorithms control how the manifest images look

Question 21

true/false: mAs only controls the quantity of photons that reaches the IR/film in analog

Answer 21

false, it controls in both analog and digital systems

Question 22

in a digital image _______ controls the brightness of the manifest image

Answer 22

computer algorithms

Question 23

in an analog image __________ controls optical density of the manifest image

Answer 23

mAs

Question 24

with respect to mAs, kVp, and optical densities/brightness, ______ “controls” and ____ “influences” quantity of photons

Answer 24

mAs, kVp

Question 25

in an image, low density is _________

Answer 25

increased brightness

Question 26

in an image, high density is __________

Answer 26

decreased brightness

Question 27

Radiographic density and tissue density are ___________ to each other

Answer 27

inversely related

Question 28

increased tissue density will make that particular area on an image _________

Answer 28

brighter/lighter

Question 29

increased radiographic density will make that particular area on an image ___________-

Answer 29

darker

Question 30

quantum mottle is due to ___________________; ______ photons and results in _________

Answer 30

insufficient mAs for anatomy of interest, too few, grainy appearance

Question 31

number of different shades of gray that can be displayed

Answer 31

gray scale

Question 32

range of shades of gray

Answer 32

scale of contrast

Question 33

Low scale of contrast, long gray scale = _____________________

Answer 33

many shades of gray, small differences

Question 34

High scale of contrast, short gray scale = ______________________________

Answer 34

not very many shades of gray; dramatic difference between high and low brightness/densities

Question 35

What is the primary technical factor that controls the scale of contrast in an analog image (film/screen image)?

Answer 35

kVp

Question 36

high kVp = ____ scale low kVp = ____ scale

Answer 36

long, short

Question 37

What is the primary factor that controls the scale of contrast in a digital image?

Answer 37

kVp

Question 38

What is the difference between radiographic contrast and subject contrast?

Answer 38

1. radiographic contrast = photographic property 2. subject contrast = result of the absorption characteristics of the anatomic tissue and the quality of the x-ray beam

Question 39

what is contrast resolution?

Answer 39

ability to distinguish between objects similar in subject contrast

Question 40

How should mAs be set to reduce patient exposure?

Answer 40

high mA station, low seconds (reciprocity law)

Question 41

what is the purpose of filtration of the beam?

Answer 41

remove low energy x-ray photons that have no diagnostic value

Question 42

what are 2 types of filtration?

Answer 42

inherent, added

Question 43

what is the type of added filtration?

Answer 43

aluminum

Question 44

tube filtration (can/can not) be changed

Answer 44

can not

Question 45

tube filtration is based on _____________

Answer 45

federal regulation standards

Question 46

increased SID = (more/less) intense beam

Answer 46

less

Question 47

inverse square law: intensity of the x-ray beam is ___________________ from the source

Answer 47

inversely proportional to the square of the distance

Question 48

direct law: The mAs/distance compensation formula provides a mathematical calculation for adjusting the ____ when changing the ______.

Answer 48

mAs, SID

Question 49

increasing or decreasing the kVp by 15% has the same effect as __________________

Answer 49

doubling or halving the mAs

Question 50

what technical factor is responsible for patient radiation dose?

Answer 50

mAs

Question 51

what equation interferes with intensity and distance?

Answer 51

inverse square law