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Flashcards in Sciences Unit 1 Deck (79):
1

Radiographic quality=

balance between the photographic and geometric characteristics of our image

2

2 Geometric properties of an image

Detail
Distortion

3

Detail

degree of accuracy of the structural lines actually recorded on the image

4

Distortion

Misrepresentation of the size or shape of the structures

5

What properties control geometric detail

recorded detail

6

What properties control photographic properties

Visibility of detail

7

Recorded Detail def

accuracy of structural lines actually recorded

8

Recorded Detail AKA

Sharpness
geometric sharpness
definition
spatial resolution
umbra

9

Umbra def

Distinctly sharp area of a shadow

10

Penumbra def

imperfect
unsharp shadow

11

Term used for measuring detail with film screen

resolution

12

How is resolution measured

Line pairs per mm, resolution tool

13

3 Factors affecting detail

Geometry
Image Receptor
Motion

14

3 Things we have control over to "fix" detail

eliminate motion
reduce OID
reduce FSS

15

What 2 factors affect detail

Distance(OID/SID)
FSS

16

Why does FSS cause geo unsharpness

beam diverges as they leave the target

17

How does distance affect geo unsharpness

^distance = ^divergence

18

Geometric blur

area where beam diverges

19

Which distace issue is most important to fix if you have to choose 1

OID

20

Geometric blur/OID relationship

Direct

21

Geo blur/SID relationship

inverse

22

What distance options will give you the highest resolution

decreased OID and increased SID

23

FSS is controlled by

the line-focus principle

24

SFS= _______ geo blur

less

25

LFS=________ geo blur

more

26

What controls penumbra

FSS

27

Where does penumbra come from

fact that photons do not come from a point source

28

FSS/Penumbra relationship

direct

29

Typical SFS mm

.6mm

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Typical LFS mm

1.2 mm

31

To min geo unsharpness use what focal spot

smalles

32

to min geo unsharpness use what SID

greatest practical

33

To min geo unsharpness use what OID

lowest

34

What shape would produce a perf sharp image

trapezoidal

35

unsharpness/detail relationship

inverse

36

GUS formula

FSSxOID / SOD

37

F/S Image Receptor faster combo = ____ resolution

less

38

slow combo f/s image receptors

increased resolution and dose

39

What do you use to test cassette quality

wire mesh

40

Matrix

the whole picture/all pixels combined

41

^matrix size=___ resolution

increase

42

smaller pixel pitch=______ resolution

higher

43

What IR size should be used for greater detail

smallest IR positive

44

Monitor quality test used

Monitor quality assurance
used to see that all four corners look alike

45

What is printer resolution determined by

dpi, dots per inch

46

Higher dpi=___ resolution

higher

47

#1 Cause of image unsharpness

Motion

48

3 Types of motion

Voluntary
Involuntary
Equipment

49

Best way to reduce motion

Communication

50

2 other ways to reduce motion

Exposure time reduction
Immobilization

51

List of immobilizers in order

1. Male relatives
2. Female relatives
3. non-tech staff
4. techs
5. students

52

Distortion

Misrepresentation of size and/or the shape of the object being imaged

53

2 Types of distortion

1. Size distortion
2. Shape distortion

54

What is seen with size distortion

Magnification

55

What 2 things is size distortion affected by

SID
OID

56

2 things seen with shape distortion

elongation
foreshortening

57

What is elongation affected by

CR/IR Misalignment

58

what is foreshortening affected by

part being misaligned

59

Elongation makes objects appear (2)

longer and thinner

60

Foreshortening makes objects appear (2)

shorter and wider

61

size distortion/OID relationship

directly proportional

62

size distortion/ SID relationship

inversely

63

Magnification formula

Image width/ object with or
SID/OID

64

Define macroradiography

When we mag intentionally for very small anatomy

65

What is Macroradiography AKA?

Magnification

66

What does macro use to image

microfocus tubes

67

What benefit does a fractional FSS have?

helps gain back some of the detail lost by the magnification

68

What is a risk of fractional FSS?

Increased OID increases pt skin dose

69

What is size distortion referred to

"true distortion"

70

What causes elongation

tube
IR alignment

71

What causes Foreshortening

Part not aligned

72

What is size distortion dependent on

CR/part/image receptor relationship

73

What should always be perpendicular to the part

CR

74

What should always be // to the part

IR

75

What is foreshortening most often caused by

the part not being parellel with iR

76

What may distortion lead to diagnostically

incorrect dx, not seen or make a fx seem worse

77

2 bones are superimposed, what will get thrown the furthest when a tube is angled?

The furthest one from the IR, or closest to the tube

78

2 reasons why we intentionally distort

trying to "undistort" anatomy that may not be parallel to the IR
To prevent superimposition of one anatomical structure over another

79

What is intentional distorment AKA

Displacement