UNIT 1: Quality Factors Review

Question 1

What are the 4 quality factors of X-Ray?

Answer 1

-Photographic: IR Exposure, Contrast
-Geometric: Spatial Resolution(detail), Distortion(Magnification & Foreshortening/Elongation)

Question 2

IR exposure is a measurement of

Answer 2

-Total amount of signal received by the Image Receptor
-Measurement of beam INTENSITY
Sensitivity Number (S#)
Exposure Index (El)
Log Median Exposure (LgM)

Question 3

Describe the relationship that the following factors have on IR exposure: mAs, kVp, Grids, Distance

Answer 3

-mAs: direct and proportional relationship
-kVp: direct relationship (uses 15% rule)
-Grid: indirect relationship (uses GCF), manipulate mAs to maintain IR exposure
-Distance: indirect relationship (uses Inverse Square Law)

Question 4

What are 3 additional influencing factors that affect IR exposure?

Answer 4

• Patient Factors
  -OID
  -Screen Speed

Question 5

If S number is too high, is the image over or underexposed?

Answer 5

Underexposed

Question 6

If S number is too low, is the image over or underexposed?

Answer 6

Overexposed

Question 7

Image vs Subject Contrast

Answer 7

-Image Contrast: difference in IR exposure between two adjacent areas on an image
-Subject Contrast: difference in x-ray intensities that are transmitted through the subject(patient) and recorded on the IR

Question 8

Long Scale vs Short Scale Contrast

Answer 8

-Long Scale: many shades of gray (more information)
-Short Scale: few shades of gray yet more “appealing” to the eye

Question 9

Describe the relationship that the following factors have on Subject Contrast: kVp, Grid, OID, Collimation

Answer 9

-kVp: indirect relationship
-Grid: direct relationship
-OID: direct relationship
-Collimation: direct relationship

Question 10

What are 3 additional influencing factors that affect Subject Contrast?

Answer 10

-Patient factors
-Contrast media
-Filtration(?)

Question 11

What is the purpose of the Look Up Table?

Answer 11

-Determine a preset grayscale for display based on the selection of the Radiographer
-Applied to the data that has standard contrast for that exam to give the desired image contrast for display

Question 12

Define Spatial Resolution

Answer 12

Degree of sharpness, or accuracy of the structural lines recorded on the image

Question 13

Describe the relationship that the following factors have on Spatial Resolution: FSS, SID, OID, Pixel Size

Answer 13

-FSS: indirect relationship
-SID: direct relationship
-OID: indirect relationship
-Pixel Size: indirect relationship

Question 14

What are 3 additional influencing factors that affect Spatial Resolution?

Answer 14

-Quantum mottle
-Motion
-Scatter(only impacts visibility, NOT recorded detail)

Question 15

What tool is used to measure spatial resolution?

Answer 15

Line pair test

*more lines= better resolution

Question 16

Define Distortion and its types

Answer 16

The misrepresentation of the size or shape of a structure being examined
-Magnification
-Foreshortening
-Elongation

Question 17

What are the two types of shape distortion and what causes them?

Answer 17

-Foreshortening: Part and IR alignment
-Elongation: Tube and IR alignment

Question 18

How does size distortion happen?

Answer 18

-Big OID
-Small SID

Question 19

Formulas

Answer 19

Question 20

Factors affecting image quality chart

Answer 20

Question 21

Frequency

Answer 21

cycles per unit of time

Question 22

Wavelength

Answer 22

Distance between two waves

Question 23

Amplitude

Answer 23

Height of the wave

Question 24

mAs

Answer 24

-Total current sent to the Cathode during exposure
-Controls the number of electrons in the thermionic cloud
-Controls Beam Intensity/quantity

Question 25

kVp

Answer 25

-Controls the Voltage sent to the anode -Controls the attraction between the electrons and the anode **-Affects both quality (but can also affect quantity)**

Question 26

Low kVp = ______ frequency

Answer 26

Low

Question 27

High kVp = _______ frequency

Answer 27

High

Question 28

A 15% increase in kVp means a _________ exposure to the IR

Answer 28

Double

Question 29

A 15% decrease in kVp means _________ exposure to the IR

Answer 29

Half

Question 30

Beam quantity is known as

Answer 30

-mAs -beam intensity -amplitude

Question 31

Beam quality is known as

Answer 31

-kVp -beam penetrability -energy -frequency

Question 32

T or F: wavelength and frequency are inversely proportional

Answer 32

True

Question 33

Cathode serves as a

Answer 33

source of electrons

Question 34

Anode serves as

Answer 34

a target, it is the source of the x-ray beams

Question 35

If we doubled the distance, the intensity would decrease by a factor of

Answer 35

4

Question 36

If we tripled the distance, the intensity would decrease by a factor of

Answer 36

9

Question 37

Quantum mottle

Answer 37

Inconsistent or uneven distribution of x-ray photons on the surface of the IR resulting in insufficient exposure

Question 38

T or F: exposure and brightness are directly related

Answer 38

False

Question 39

CR vs DR

Answer 39

Question 40

Is quantum mottle over or under exposure

Answer 40

Under exposure

Question 41

X-ray tube labeled

Answer 41