10. Assessing Distortion

Question 1

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

Answer 1

Assessing Distortion

Question 2

is a misrepresentation of the size or shape of

the structures being examined

Answer 2

Distortion

Question 3

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

the anatomical part being imaged

Answer 3

Distortion

Question 4

This misrepresentation can be classified as either ____ or

_____ distortion

Answer 4

size,

shape

Question 5

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

Answer 5

difficult

Question 6

Size distortion can be only magnified with ______

radiography

Answer 6

film/screen

Question 7

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

Answer 7

point source

Question 8

In all instances, ______ magnification size distortion

______ the resolution of recorded detail

Answer 8

reduced,

increases

Question 9

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

Answer 9

SID (max),

OID (min)

Question 10

The ____ has a major effect on magnification

Answer 10

SID

Question 11

The ____ is the critical distance for magnification and resolution

Answer 11

OID

Question 12

Although _______ has developed as the current

routine SID, this was not always so.

Answer 12

40” (100 cm)

Question 13

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

Answer 13

1918,

20 in or 50 cm

Question 14

In ____ “Modern X-ray Technic”, ______

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

Answer 14

1928,

Ed Jerman

Question 15

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

recommended distances from

Answer 15

25” (63 cm) to 36” (90 cm)

Question 16

_______ book, “Medical Radiographic Technic” – ______

Answer 16

Glenn Files’ 1945,

40’ (100cm) SID

Question 17

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

Answer 17

48” (120 cm)

Question 18

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

Answer 18

72” (180cm)

Question 19

Another critical factor in both magnification and

resolution

Answer 19

Object-to-Image Receptor Distance

Question 20

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

Answer 20

opposite

Question 21

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

Answer 21

Shape distortion

Question 22

projects the object so it appears to be longer

than it really is

Answer 22

Elongation

Question 23

projects the image so it appears shorter than it really is

Answer 23

Foreshortening

Question 24

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

Answer 24

Shape distortion

Question 25

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

Answer 25

central ray

Question 26

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

Answer 26

creative positioning

Question 27

is the theoretical photon that exits from the | exact center of the focal spot

Answer 27

Central ray

Question 28

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

Answer 28

perpendicular

Question 29

Whenever the central ray is not _______, some | degree of shape distortion will result

Answer 29

perpendicular

Question 30

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

Answer 30

farther, | greater

Question 31

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

Answer 31

angulation

Question 32

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

Answer 32

perpendicular (central ray), | parallel (IR)

Question 33

occurs when there is poor alignment of the | tube and/or image receptor

Answer 33

Elongation

Question 34

occurs only when there is poor alignment | of the part

Answer 34

Foreshortening

Question 35

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

Answer 35

perpendicular (central ray), | parallel (IR)

Question 36

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

Answer 36

Angulation

Question 37

The angulation of the tube is designed to cause a | controlled or expected amount of shape distortion to avoid ________

Answer 37

superimpositions

Question 38

The most common direction of the tube angle is ______

Answer 38

longitudinal

Question 39

Longitudinal angulations are usually termed ______ | when the tube is angled toward the head of the patient

Answer 39

cephalad

Question 40

Longitudinal angulations are usually termed ______ | when the tube is angled toward the patient’s feet

Answer 40

caudad

Question 41

Some radiographic tubes can also be angled

Answer 41

transversely

Question 42

transversely (sometimes referred to as “___”)

Answer 42

roll

Question 43

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

Answer 43

Degree

Question 44

is a more subjective evaluation than size

Answer 44

Shape distortion

Question 45

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

Answer 45

Shape distortion

Question 46

is generally a matter of | magnification

Answer 46

Size distortion

Question 47

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

Answer 47

Shape distortion