Unit 4

Question 1

Image Contrast

Answer 1

the degree of difference between the light and dark areas of a radiograph

Question 2

What makes blacks, whites, and grays?

Answer 2

differential absorption

Question 3

Subject Contrast

Answer 3

the component of image contrast determined by the size, shape, and x-ray attenuating characteristic of the subject who is being examined and the energy of the x-ray beam

Question 4

What controls subject contrast?

Answer 4

kVp

Question 5

What is the process that produces subject contrast?

Answer 5

Differential Absorption

Question 6

Differential Absorption

Answer 6

the difference between the x-ray photons absorbed and those that penetrate the body

Question 7

Attenuation

Answer 7

removal of any photons from the primary beam before striking the image receptor

Question 8

Causes or attenuation

Answer 8

Patient absorption
Compton scatter

Question 9

differential attenuation

Answer 9

a form of primary beam attenuation specific to patient absorption and compton scatter

Question 10

Absorption

Answer 10

refers to x-ray photons that are attenuated by the body and do not reach the IR

Question 11

Transmission

Answer 11

refers to x-ray photons that pass through the body and reach the IR

Question 12

Primary Beam

Answer 12

the x-ray beam as it is upon exiting the collimator and exposing the patient

Question 13

Remnant Beam

Answer 13

the x-ray beam that remains after interaction with the patient and that is exiting the patient to expose the IR

Question 14

What is the remnant beam composed of?

Answer 14

transmitted photons and scattered photons

Question 15

Radiopaque

Answer 15

body structures that readily absorb x-ray photons

(bones)

Question 16

Radiolucent

Answer 16

less dense body structures that have much lower probability of absorption

(air-filled lungs)

Question 17

Photoelectric Effect

Answer 17

absorption

Question 18

How is absorption represented radiographically?

Answer 18

white

Question 19

How is transmission represented radiographically?

Answer 19

black

Question 20

What are the various shades of gray caused by?

Answer 20

tissues of the body where photons aren’t completely absorbed or transmitted

Question 21

High contrast

Answer 21

large differences in brightness (B/W) on a radiograph

Question 22

What is brightness?

Answer 22

exposure

Question 23

What “scale” is high contrast?

Answer 23

Short Gray-Scale

Question 24

Does short gray scale have more B/W or more Gray?

Answer 24

More B/W.

Only a few grays

Question 25

A decrease in kVp results in _____ contrast and _____ gray scale.

Answer 25

A decrease in kVp results in high contrast and short gray scale.

Question 26

An increase in kVp results in ______ contrast and _____ gray scale

Answer 26

An increase in kVp results in low contrast and long gray scale

Question 27

low contrast

Answer 27

small differences in brightness on a radiograph

Question 28

What "scale" is low contrast?

Answer 28

Long gray scale

Question 29

Does long gray scale have more b/w or more gray?

Answer 29

More gray Some b/w

Question 30

What term describes the total number of differences in brightness levels that are visible on a radiograph?

Answer 30

Gray Scale

Question 31

Bit Depth

Answer 31

total brightness levels that an imaging monitor is capable of displaying

Question 32

8 factors affecting image contrast

Answer 32

1. x-ray beam quality (kVp) 2. differential absorption (subject contrast) 3. Computer processing and display 4. filtration 5. compton scatter 6. radiographic grids 7. OID 8. beam restriction

Question 33

high kvp = ___ contrast

Answer 33

high kvp = low contrast

Question 34

low contrast = _____ gray scale

Answer 34

long

Question 35

8 factors: kVp increasing kvp _____ pentrability

Answer 35

increases

Question 36

8 factors: kVp a greater percentage of the beam passing through the patient = a ____ percentage of differential absorption

Answer 36

decreased

Question 37

8 factors: kVp a decreased percentage of differential absorption = ____ gray scale, and ___ image contrast

Answer 37

long gray scale low image contrast

Question 38

8 factors: kVp decreasing kvp = _____ penetrability

Answer 38

decreased

Question 39

8 factors: kVp a decreased percentage of beam passing through the patient = ____ percentage of differential absorption

Answer 39

increased

Question 40

8 factors: kVp an increased percentage of differential absorption = ____ gray scale, and ____ image contrast

Answer 40

short gray scale high image contrast

Question 41

Contrast is the percentage of _______ vs. ______

Answer 41

absorption vs transmission

Question 42

8 factors: differential absorption higher levels of differential absorption = ____ black and white

Answer 42

more

Question 43

8 factors: differential absorption increased differential absorption = ____ subject contrast, and ____ gray scale

Answer 43

high subject contrast short gray scale

Question 44

8 factors: differential absorption decreased differential absorption = ____ subject contrast, and ___ gray scale

Answer 44

low subject contrast long gray scale

Question 45

8 factors: differential absorption more matter =

Answer 45

more scatter

Question 46

is scatter diagnostic?

Answer 46

no

Question 47

Scatter has what effect on contrast?

Answer 47

decreases contrast

Question 48

8 factors: Computer processing and display Look Up Table (LUT)

Answer 48

primary controlling factor in image contrast

Question 49

8 factors: Computer processing and display when does the LUT take place?

Answer 49

after the exposure is made and the image is being processed by the imaging system software

Question 50

8 factors: filtration filtration

Answer 50

removes low energy photons from the x-ray beam

Question 51

8 factors: filtration an increase in filtration = a _____ in contrast

Answer 51

decrease

Question 52

filtration and contrast have what type of relationship?

Answer 52

indirect

Question 53

8 factors: filtration an increase in filtration = a _____ in differential absorption

Answer 53

decrease

Question 54

8 factors: filtration a decrease in filtration = a ____ in differential absorption

Answer 54

increase

Question 55

8 factors: filtration a increase in filtration = a ____ in differential absorption

Answer 55

decrease

Question 56

8 factors: compton scatter compton scatter

Answer 56

an x-ray photon that interacts with the body and then scatters off of its original trajectory

Question 57

8 factors: compton scatter does compton scatter contribute useful information

Answer 57

no

Question 58

8 factors: compton scatter what does compton scatter do to image contrast?

Answer 58

decreases