Ch 10 Radiographic Quality Flashcards Preview

Slockett's Rad Exposures > Ch 10 Radiographic Quality > Flashcards

Flashcards in Ch 10 Radiographic Quality Deck (71):
1

What is radiographic quality?

The exactness of representation of the anatomic part of interest in the finished radiograph

2

What are the (3) types of radiographic quality factors?

1. Film factors (not allot of control over)
2. Geometric factors (little bit of control over)
3. Subject factors (no control over)

3

What quality factor do we have no control over?

Subject matter

4

What are the film factors?

Characteristic Curve
-Speed
-Latitude
-Density
-Contrast

Processing:
-Time
-Temperature

5

What are the Geometric Factors?

-Distortion
-Magnification
-Blur

6

What are the Subject Factors?

Contrast
Thickness
Density
Atomic #
Motion

7

Quality is the same for everyone? T/F

False

8

What is the criteria for evaluating quality?

-Spatial resolution
-Contrast resolution
-Artifacts
-Noise

9

What is spatial resolution?

Everything is in it's appropriate place

10

What is contrast resolution?

Scales of gray

11

Spatial resolution is the ability to image objects that have ____ subject contrast.

High

12

Contrast resolution is the ability to detract or distinguish objects that have _____ subject contrast.

Similar

13

Which modality best demonstrates spatial resolution?

Diagnostic

14

What is noise?

The undesirable fluctuation of the OD of the image

15

Which modality best demonstrates contrast resolution?

CT, MRI

16

How do we get noise on an image?

-Film graininess
-Structure mottle- phosphor intensity screen
-Quantum mottle-
-Scatter Radiation-impact OD

17

What is Quantum Mottle?

Freckled appearance

18

What is the quality rule?

Fast image receptors have high noise and low spatial & contrast resolution

19

What is another name for the D max?

Shoulder

20

What is the Characteristic curve?

The graphic relationship between optical density and radiation exposure

21

What are the two pieces needed to contract a characteristic curve?

Sensitometer
Densitometer

22

What is the highest portion of the Characteristic curve?

Shoulder (D max)

23

What is the lowest portion of the Characteristic curve?

Toe

24

What is another name for the Characteristic curve?

H & D curve

25

What is the most useful part of the characteristic curve?

Straight line portion

26

Is D max useful?

-No, it's black
-Densest part
-Burnt out

27

Is the Toe useful?

No, too white
-Washed out
-Loss of density

28

Where do you find your grays on the Characteristic curve?

In the straight line portion

29

What is the portion below the toe called?

Base + Fog (B+F)

30

What is B+F?

-What is inherent in the film and hasn't been exposed
-Anything outside the range of exposure

31

In B+F, what is Base?

What the manufacturer put in the film

32

In B+F, what is F?

Fog in the dark room

33

What is optical density?

Measurement of light incident on a processed film and the level of light transmitted through the film

34

What chemical produces the black?

Hydroqonone

35

What chemical produces the shades of gray?

Phenedone

36

Base + Fog= ?

Optical Density

37

Base + Fog should not exceed...

0.3

38

B + F (below toe) falls ______ the exposure range.

Outside

39

What is the OD range of the unexposed and processed radiographic films?

0.1- 0.3

40

Hydroqonone and phenedone work _______ to produce the blacks and grays.

Synergistically

41

Optical density is looking at what's _____ and what passes through

Inherent

42

B+F is the _______ and processed part of the processed radiographic film.

Unexposed

43

What is the base density?

0.1

44

What is the Fog density?

Doesn't exceed 0.2

45

What is the useful range of optical density?

0.25- 2.5 LRE

46

What are some reasons you might get an OD greater than 0.3?

-Aging of the film
-Processor temp
-Chemical fumes
-Light
-Radiation

47

What does LRE stand for?

Log Relative Exposure

48

What are the OD ranges dependent on?

-Viewbox illumination
-Viewing conditions
-Shape of characteristic curve

49

Optical density is measured ________.

Log rhythmically

50

What are the (2) types of Radiographic Contrast?

1. Image receptor contrast
2. Subject contrast

51

What is Image Receptor Contrast?

Inherent in the film and influenced by processing
(Things we cannot control)

52

What is Subject Contrast?

That which attenuates through our patient and the kVp we performed the image with
(other than kVp we cannot control)

53

How do we have any control over radiographic contrast, when it's determined by things we have no control over?

By adapting

54

For the same film type a change in _____ will affect contrast only when above or below the straight line portion.

Density

55

Contrast is defined by the slope of the ______ _____ portion.

Straight line

56

When density impacts _____ it is above or below the straight line portion

Contrast

57

Contrast that is defined by the slope of the straight line portion is also know as...

Average gradient

58

When changing technique at the D max...

Cut mAs in half

59

When changing technique at the toe you...

Double mAs

60

What is the Average Gradient?

The slope of the straight line drawn between two points on the characteristic curve at 0.25 and 2.0 above B+ F

61

What is the useful range of average gradient?

0.25- 2.0

62

The B+ F should not exceed...

0.3

63

What are the average gradient constants?

0.25
2.0

64

What is the B+ F range?

0.1- 0.3

65

When connecting (2) points on an H & D curve, the line is called the...

-Average Gradient
-Straight line portion
-Useful portion

66

What is the formula to determine Average Gradient?

AG= OD2 - OD1
_________
LRE 2 – LRE 1

67

The speed point on a film is defined as:

B + F+1

68

How do you chart a speed point?

As an open circle

69

When looking at a speed chart, the faster film is usually on the ____.

Left
-It has a shorter scale of contrast
-Goes from white to black faster

70

Speed point is ___ point above B + F.

1

71

What is speed?

How fast a film develops