111- Recorded Detail And Distortion Test Flashcards Preview

Radiography > 111- Recorded Detail And Distortion Test > Flashcards

Flashcards in 111- Recorded Detail And Distortion Test Deck (40)
Loading flashcards...
1
Q

Define recorded detail and provide other terms used to express recorded detail

A
Degree of geometric sharpness/ accuracy of structural lines
Definition
Sharpness
Resolution
Spatial resolution
2
Q

What is the unit of resolution

A

Line pairs per mm

3
Q

Define umbra and penumbra

A

Umbra- sharp area

Penumbra- unsnarl area

4
Q

Define distortion and list the types of distortion

A

Misrepresentation of size or shape of part

Magnification, foreshortening, elongation

5
Q

What factors affect size distortion

A

OID and SID

6
Q

Explain how size distortion happens

A

Increased OID

7
Q

How does patient thickness affect distortion

A

Pt thickness adds inherent OID which can magnify structures

8
Q

What factors affect shape distortion

A

CR, IR, body part

9
Q

Explain how shape distortion happens

A

Poor alignment if CR, IR, Ir body part

10
Q

How will FSS, motion, OID and SID impact recorded detail

A

Decrease FSS increase detail
Decrease motion increase detail
Decrease OID increase detail
Increase SID increase detail

11
Q

What are the two photographic properties of radiography and the two geometric properties

A

Photographic- contrast and density

Geometric- detail and distortion

12
Q

List factors that affect visibility of detail

A

FSS, OID/SID, motion, kvp, mas

13
Q

How will changing from a small to large focal spot affect density

A

No effect

14
Q

How will changing from a small to large focal spot affect contrast

A

No effect

15
Q

How will changing from a small to large focal spot affect detail

A

Decrease detail

16
Q

How will changing from a small to large focal spot affect distortion

A

No effect

17
Q

What factors affect spatial resolution in digital imaging?

A

Matrix size, pixel size, grayscale bit depth

18
Q

In digital imaging, which axis represents height, width, and depth

A

Height - y
Width- x
Depth- z

19
Q

What is the difference between system noise and quantum noise

A

System- background frequency interference

Quantum- lack of Xray photons

20
Q

Describe how noise appears on an image

A

Grainy

21
Q

If an image displays quantum noise, what caused this

A

Underexposure

22
Q

How will you fix quantum noise on a digital image

A

Increase mas

23
Q

Which is best for demonstrating increased spatial resolution, a high or low SNR

A

High SNR

24
Q

As FSS decreases, what happens to umbra

A

Increases

25
Q

As FSS decreases, what happens to penumbra

A

Decreases

26
Q

As FSS decreases, what happens to resolution

A

Increases

27
Q

As FSS decreases, what happens to recorded detail

A

Increases

28
Q

How does FSS affect penumbra

A

Decrease FSS, decrease penumbra

29
Q

How does OID affect penumbra

A

Decrease OID decrease penumbra

30
Q

How does SID affect penumbra

A

Increase SID decrease penumbra

31
Q

How does size distortion affect resolution

A

Decreases resolution

32
Q

What is the best method for controlling involuntary motion

A

Short exposure time

33
Q

What is the best way for controlling voluntary motion

A

Clear instructions

34
Q

What is the last resort for controlling patient motion

A

Immobilization

35
Q

Which distance is most associated with pt skin dose and why

A

SOD, the closer the source is to pt, more radiation is absorbed

36
Q

Explain the relationship between a larger patient and entrance skin exposure

A

Bigger the patient, more ESE

37
Q

How does the shape of the body part affect penumbra

A

Shapes in the body that match beam divergence create the least penumbra

38
Q

What are two different formulas that can be used to calculate MF

A

SID/SOD

Image/object size

39
Q

Magnification occurs when the body part is moved closer to or farther away from the central ray

A

Closer

40
Q

Proper alignment is achieved when the central ray is ___ to the part and ____ to the image receptor

A

Perpendicular, perpendicular