Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

RT 204 > 10. Assessing Distortion > Flashcards

10. Assessing Distortion Flashcards

1
Q

is the second of the 2 geometric properties affecting radiographic image quality

A

Assessing Distortion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

is a misrepresentation of the size or shape of

the structures being examined

A

Distortion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

It creates a misrepresentation of the size and/or shape of

the anatomical part being imaged

A

Distortion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

This misrepresentation can be classified as either ____ or

_____ distortion

A

size,

shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Distortion can be _____ to determine even when normal sizes and shapes are known

A

difficult

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Size distortion can be only magnified with ______

radiography

A

film/screen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Since it is not possible to reflect or refract x-ray photons by ordinary methods, they can only diverge from their
______

A

point source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

In all instances, ______ magnification size distortion

______ the resolution of recorded detail

A

reduced,

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Magnification size distortion is controlled by positioning
the body part and tube to maximize ____ while
minimizing ____

A

SID (max),

OID (min)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The ____ has a major effect on magnification

A

SID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The ____ is the critical distance for magnification and resolution

A

OID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Although _______ has developed as the current

routine SID, this was not always so.

A

40” (100 cm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The first x-ray techniques book in the United States is generally recognized to be the ____ “Extract from the United States Army X-ray manual” – ______ is discussed as a reasonable SID

A

1918,

20 in or 50 cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In ____ “Modern X-ray Technic”, ______

recommended distances from 25” (63 cm) to 36” (90 cm)

A

1928,

Ed Jerman

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In 1928 “Modern X-ray Technic”, Ed Jerman

recommended distances from

A

25” (63 cm) to 36” (90 cm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

_______ book, “Medical Radiographic Technic” – ______

A

Glenn Files’ 1945,

40’ (100cm) SID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Some institutions are adopting the ______ as a routine distance and the movement appears to be growing

A

48” (120 cm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

For many, many years chest radiography has been
performed at _______ because the erect positioning arrangement permits horizontal beam to be used and the increased SID effectively minimizes the
magnification of the heart shadow

A

72” (180cm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Another critical factor in both magnification and

resolution

A

Object-to-Image Receptor Distance

20
Q

When describing objects, it is important to remember
the size and distance relationship in a radiographically
projected image is the ______ of that perceived
visually

A

opposite

21
Q

is the misrepresentation by unequal magnification of the actual shape of the structure being examined

A

Shape distortion

22
Q

projects the object so it appears to be longer

than it really is

A

Elongation

23
Q

projects the image so it appears shorter than it really is

A

Foreshortening

24
Q

often results because structures lie normally at different levels within the body. It also occurs due the divergence of the xray beam

A

Shape distortion

25
Q

Shape distortion can be caused or avoided by careful alignment of the _____ with the anatomical part
and the image receptor

A

central ray

26
Q

When the position of the body part or object within the body does not permit this alignment, _______ must be utilized

A

creative positioning

27
Q

is the theoretical photon that exits from the

exact center of the focal spot

A

Central ray

28
Q

Central ray ideally is intended to be projected ______ to both the anatomical part & the image receptor

A

perpendicular

29
Q

Whenever the central ray is not _______, some

degree of shape distortion will result

A

perpendicular

30
Q

Any structure that will is not positioned at the central
ray will be distorted because of the divergence of the beam – the _____ from the central ray, the _____ the
distortion

A

farther,

greater

31
Q

When a part is superimposed, central ray _______ can be a useful tool to provide a projection that would otherwise be impossible to differentiate from overlying
structures

A

angulation

32
Q

The long axis of the anatomical part, or object, is
intended to be positioned _______ to the central
ray and ______ to the image receptor.

A

perpendicular (central ray),

parallel (IR)

33
Q

occurs when there is poor alignment of the

tube and/or image receptor

A

Elongation

34
Q

occurs only when there is poor alignment

of the part

A

Foreshortening

35
Q

The anatomical part is normally positioned with its long axis _____ to the central ray and _____ to the image receptor.

A

perpendicular (central ray),

parallel (IR)

36
Q

Refers to the direction and degree the tube is moved
from its normal position perpendicular to the image
receptor

A

Angulation

37
Q

The angulation of the tube is designed to cause a

controlled or expected amount of shape distortion to avoid ________

A

superimpositions

38
Q

The most common direction of the tube angle is ______

A

longitudinal

39
Q

Longitudinal angulations are usually termed ______

when the tube is angled toward the head of the patient

A

cephalad

40
Q

Longitudinal angulations are usually termed ______

when the tube is angled toward the patient’s feet

A

caudad

41
Q

Some radiographic tubes can also be angled

A

transversely

42
Q

transversely (sometimes referred to as “___”)

A

roll

43
Q

is simply a method of describing the exact
amount of angulation and is usually stated as the angle
between the central ray and the image receptor plane
from the standard reference point of perpendicularity

A

Degree

44
Q

is a more subjective evaluation than size

A

Shape distortion

45
Q

It is much more difficult to assess because there is no effect that can be calculated, as in the magnification factor for size
distortion

A

Shape distortion

46
Q

is generally a matter of

magnification

A

Size distortion

47
Q

involves both elongation and
foreshortening and is a serious alteration in the
projection image

A

Shape distortion

RT 204 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions