Subject Factors

Question 1

Name all six subject factors

Answer 1

Subject Contrast
Patient Thickness
Tissue mass density
Effective Atomic number
Object shape
Kilovolt peak

Question 2

-the “third general group” of factors that affect radiographic quality involve the patient
-“associated not so much” with the positioning” of the patient

Answer 2

Subject Factors

Question 3

The contrast of the radiograph “viewed on an illuminator”

Answer 3

Radiographic Contrast

Question 4

The degree of subject Contrast is “directly proportional” to the relative number of x-rays leaving those sections of the body

Answer 4

Patient Thickness

Question 5

“Different sections of the body” may have equal thickness yet different mass densities
-these materials have the same thickness and chemical composition

Answer 5

Tissue mass density

Question 6

Contrast media are effective because “they accentuate” subject Contrast through enhanced

Answer 6

Photoelectric absorption

Question 7

When the Effective Atomic number of _______ is very much_________, subject Contrast is___________

Answer 7

Adjacent tissues, different, very high.

Question 8

The high atomic numbers of _______ and ________ result in extremely _____ subject Contrast

Answer 8

Iodine, barium, high

Question 9

Subject Contrast can be “enhanced greatly” by the use of

Answer 9

Contrast media

Question 10

The shape of anatomical structure under investigation influences it’s radiograph quality, not only through its “geometry” but also through its contribution to subject Contrast

Answer 10

Object shape

Question 11

“The characteristics”of the subject that affects subject contrast is sometimes called

Answer 11

Absorption blur

Question 12

The shape of the structure under investigation “contributes to”

Answer 12

Absorption blur

Question 13

It “reduces the spatial resolution and the contrast resolution of any anatomical structure”, but it is most troublesome during interventional procedures in which vessels with small diameters are examined

Answer 13

Object shape

Question 14

-Is the most important influence on Subject Contrast
-also influences film contrast but not to the extent that it controls subject contrast

Answer 14

kVp

Question 15

If the kvp is high and the subject contrast is low it is

Answer 15

Long gray scale

Question 16

If the kvp is low and the subject contrast is high it is

Answer 16

Short gray scale

Question 17

The “absolute magnitude” of subject contrast, however, is greatly controlled by the

Answer 17

kVp of operation

Question 18

Movement of the patient or the x-ray tube during exposure results in blurring of the radiographic image.

Answer 18

Motion blur

Question 19

The radiographer can reduce motion blur by carefully instructing the patient

Answer 19

“Take a deep breath and hold it. Don’t move.”

Question 20

Usually the cause of motion blur

Answer 20

Patient motion

Question 21

Voluntary motion of the limbs and muscles is controlled by

Answer 21

Communication or Immobilization

Question 22

Involuntary motion of the heart and lungs is controlled by

Answer 22

Short exposure time

Question 23

Procedures for reducing motion blur

Answer 23

-Use the shortest possible exposure time
-restrict patient motion by providing instruction or using a restraining device
-use a large sid
-use a small oid

Question 24

“Requires that the anatomical structure under investigation” be placed as close to the image receptor

Answer 24

Proper patient positioning

Question 25

Most other radiographs use

Answer 25

double emulsion films with screens

Question 26

A ______ of screen film image receptor is used throughout a radiology department for a given type of examination.

Answer 26

Standard type

Question 27

Use of intensifying screen _______ patient dose by a factor of _______

Answer 27

Decreases, At least 20

Question 28

As the speed of the image receptor______ radiographic noise _____ and spatial resolution is______

Answer 28

Increases, increases, reduced

Question 29

Low contrast imaging procedures have________, or _________, in producing an _______

Answer 29

Wider latitude, margin of error, acceptable radiograph

Question 30

Keep exposure time______

Answer 30

as short as possible

Question 31

The primary control of radiographic contrast is

Answer 31

kVp

Question 32

The primary control of OD is

Answer 32

mAs

Question 33

Before each examination, the radiologic technologist must select the optimum radiographic technique Factors, that is, ______, _____, and ______

Answer 33

kVp, mAs, and exposure time

Question 34

The radiologic technologist has no control over the four previous factors

Answer 34

kVp

Question 35

Tools for improved radiographic image quality

Answer 35

Patient positioning and image receptors