Image Acquisition and Technical Evaluation

Question 1

How does an increase in mAs affect receptor exposure, spatial resoulation, and distortion?

Answer 1

RE - Increase
Spat Res - No effect
Distortion - No effect

Question 2

How does an increase in kVp affect receptor exposure, spatial resoulation, and distortion?

Answer 2

RE - Increase
Spat Res - No effect
Distortion - No effect

Question 3

How does an increase in OID affect receptor exposure, spatial resoulation, and distortion?

Answer 3

RE - No effect
Spat Res - Decrease
Distortion - Increase (size)

Question 4

How does an increase in SID affect receptor exposure, spatial resoulation, and distortion?

Answer 4

RE - Decrease
Spat Res - Increase
Distortion - Decrease (size)

Question 5

How does an increase in FSS affect receptor exposure, spatial resoulation, and distortion?

Answer 5

RE - No effect
Spat Res - Decrease
Distortion - No effect

Question 6

How does an increase in grid ratio affect receptor exposure, spatial resoulation, and distortion?

Answer 6

RE - Decrease
Spat Res - No effect
Distortion - No effect

Question 7

How does an increase in tube filtration affect receptor exposure, spatial resoulation, and distortion?

Answer 7

RE - Decrease
Spat Res - No effect
Distortion - No effect

Question 8

How does an increase in beam restriction affect receptor exposure, spatial resoulation, and distortion?

Answer 8

RE - Decrease
Spat Res - No effect
Distortion - No effect

Question 9

How does an increase in motion affect receptor exposure, spatial resoulation, and distortion?

Answer 9

RE - No effect
Spat Res - Decrease
Distortion - No effect

Question 10

How does an increase in anode heel effect affect receptor exposure, spatial resoulation, and distortion?

Answer 10

RE - Decrease
Spat Res - No effect
Distortion - No effect

Question 11

How does an increase in patient size affect receptor exposure, spatial resoulation, and distortion?

Answer 11

RE - Decrease
Spat Res - Decrease
Distortion - Increase (size)

Question 12

How does an additive pathology affect receptor exposure, spatial resoulation, and distortion?

Answer 12

RE - Decrease
Spat Res - No effect
Distortion - No effect

Question 13

How does an increase in angle (tube, part, receptor) affect receptor exposure, spatial resoulation, and distortion?

Answer 13

RE - No effect
Spat Res - Decrease
Distortion - Increase (shape)

Question 14

How does an increase in pixel size affect receptor exposure, spatial resoulation, and distortion?

Answer 14

RE - No effect
Spat Res - Decrease
Distortion - No effect

Question 15

How does an increase in pixel pitch affect receptor exposure, spatial resoulation, and distortion?

Answer 15

RE - No effect
Spat Res -Decrease
Distortion - No effect

Question 16

How does an increase in DEL fill factor affect receptor exposure, spatial resoulation, and distortion?

Answer 16

RE - Increase
Spat Res - Increase
Distortion - No effect

Question 17

How does an increase in sampling frequency (CR) affect receptor exposure, spatial resoulation, and distortion?

Answer 17

RE - No effect
Spat Res - Increase
Distortion - No effect

Question 18

How does an increase in matrix size affect receptor exposure, spatial resoulation, and distortion?

Answer 18

RE - No effect
Spat Res - Increase
Distortion - No effect

Question 19

How does an increase in FOV affect receptor exposure, spatial resoulation, and distortion?

Answer 19

RE - No effect
Spat Res - Decrease
Distortion - No effect

Question 20

How does an increase in MTF affect receptor exposure, spatial resoulation, and distortion?

Answer 20

RE - No effect
Spat Res - Increase
Distortion - No effect

Question 21

How does an increase in DQE affect receptor exposure, spatial resoulation, and distortion?

Answer 21

RE - Increase
Spat Res - No effect
Distortion - No effect

Question 22

How does an increase in DEL size affect receptor exposure, spatial resoulation, and distortion?

Answer 22

RE - No effect
Spat Res - Decrease
Distortion - No effect

Question 23

What is the main controller of spatial resolution in DR?

Answer 23

Pixels

Question 24

What is the main controller of spatial resolution in CR?

Answer 24

Sampling frequency

Question 25

Definition of MTF:

Answer 25

Measurement of systems ability to transfer object information to the image

Question 26

Definition of DQE:

Answer 26

Measurement of systems ability to convert xray intensity into electronic signal

Question 27

What is a good number for MTF?

Answer 27

.7 - .9

Question 28

As FOV increases for a fixed matrix size, the size of each pixel:

Answer 28

Increases

Question 29

For a fixed FOV with an increase in matrix size, the size of each pixel:

Answer 29

Decreases

Question 30

Rank from least dense to most dense: Bone, Water, Air, Muscle, Fat

Answer 30

Air Fat Water Muscle Bone

Question 31

What is the 15% rule?

Answer 31

A 15% increase or decrease in kVp, keeping all other factors constant, will result in doubling or halving receptor exposure

Question 32

It is determined that an underexposed abdominal radiograph needs to be repeated with the exposure factors doubled. If the original exposure factors were 70@32, what new exposure factors should be used to improve this image?

Answer 32

80.5@32

Question 33

What is the grid ratio?

Answer 33

Height/Distance or Width of interspace

Question 34

To maintain a desired amount of receptor exposure, changes in ____ are required to compensate for the presence of a grid

Answer 34

mAs

Question 35

Grid conversion formula

Answer 35

Old mAs/New mAs = Old GF/New GF

Question 36

Grid ratio multiplication factors:

Answer 36

No grid/IR speed - 1 5:1 - 2 6:1 - 3 8:1 - 4 10:1 - 5 12:1 - 5 16:1 - 6

Question 37

When converting from an 8:1 grid to a 12:1 grid, the radiographer would need to increase mAs from 20 to ___ in order to maintain the same receptor exposure

Answer 37

25

Question 38

Additive diseases that affect multiple sites:

Answer 38

Edema Tumor

Question 39

Additive diseases that affect the chest:

Answer 39

Atelectasis Cardiomegaly CHF Pleural Effusion Pneumonia TB

Question 40

Additive diseases that affect the abdomen:

Answer 40

Ascites

Question 41

Additive diseases that affect extremities and the skull:

Answer 41

Hydrocephalus Paget's disease

Question 42

Destructive diseases that affect multiple sites:

Answer 42

Atrophy

Question 43

Destructive diseases that affect the chest

Answer 43

Emphysema Pneumothorax

Question 44

Destrucitve diseases that affect the abdomen

Answer 44

Bowel obstruction

Question 45

Destructive diseases that affect extremities and the skull

Answer 45

Carcinoma Degenerative arthritis Gout Multiple myeloma Osteomalacia Osteoporosis

Question 46

What is the anode heel effect?

Answer 46

Variation in x-ray beam intensity with an increase in beam intensity toward the cathode end of the beam and a decrease in intensity toward the anode end of the beam

Question 47

When is the anode heel effect most prominent?

Answer 47

When attempting to produce images that require a long field size combined with a body part of varying part thickness at its extremes (AP tspine, AP femur)

Question 48

When needed, place the thickest portion of the anatomy toward the _______ side

Answer 48

Cathode

Question 49

What is the pimary controlled factor of subject contrast?

Answer 49

kVp

Question 50

What is umbra?

Answer 50

Area of image sharpness

Question 51

What is penumbra?

Answer 51

Area of unsharpness surrounding the image

Question 52

Is penumbra greater on the anode or cathode side?

Answer 52

Cathode

Question 53

What is ARP (automatically programmed radiography) and when is it used?

Answer 53

Pre-programmed technique charts Used in table top exams

Question 54

What is a fixed kVp chart and what are the pros/cons?

Answer 54

Fixed kVp, variable mAs Contrast is more consistent, but more repeats due to longer exposure times and more patient motion

Question 55

What is a variable kVp chart and what are the pros/cons?

Answer 55

Variable kVp, fixed mAs. kVp is determined by using calipers to measure body part thickness. Assures the penetration of the object, but contrast is not consistent

Question 56

When using a variable kVp chart, a __ kV change is made for each centimeter in part thickness

Answer 56

2 kV

Question 57

How much should kVp increase for wet plaster casts?

Answer 57

8-10

Question 58

How much should kVp increase for dry plaster casts?

Answer 58

5-7

Question 59

How much should kVp increase for fiberglass casts?

Answer 59

3-4

Question 60

Parts measuring greater than ____ cm require the use of a grid

Answer 60

10-13

Question 61

How does a tech adjust the rate of exposure when using AEC?

Answer 61

Density control

Question 62

How is spatial resolution measured?

Answer 62

lp/mm

Question 63

What is the smallest area depcited in an image?

Answer 63

Pixel

Question 64

How is the size of a pixel measured?

Answer 64

End to end

Question 65

How is the pitch of a pixel measured?

Answer 65

Center to center

Question 66

As pixel size increases, spatial resolution:

Answer 66

Decreases

Question 67

As pixel pitch increases, spatial resoltuion:

Answer 67

Decreases

Question 68

What is pixel density?

Answer 68

Number of pixels per mm

Question 69

How is pixel density determined?

Answer 69

By pixel size and pitch

Question 70

As pixel size decreases, pixel density:

Answer 70

Increases

Question 71

DEL size is used with _____ capture radiography

Answer 71

Direct

Question 72

As DEL increases, spatial resoltuion:

Answer 72

Decreases

Question 73

What is the DEL fill factor?

Answer 73

Ratio of pixels light sensitive area versus total area

Question 74

A two dimensional array of pixels (x and y)

Answer 74

Matrix

Question 75

Matrix size is the total number of:

Answer 75

Pixels

Question 76

Matrix size is dependant upon:

Answer 76

FOV and pixel density

Question 77

FOV is 35cm by 43cm at 5 pixels/mm. What is the matrix size?

Answer 77

3,762,500 350mm x 5 = 1750 430mm x 5 = 2150 1750 x 2150 = 3,762,500

Question 78

Increase in IR size results in an _______ in matrix size

Answer 78

Increase

Question 79

Decreasing pixel size results in __________ matrix size and _________ spatial resolution

Answer 79

Increased Increased

Question 80

Decreasing pixel size ___________ visibility of small structures and __________ spatial resoltuion

Answer 80

Increases Increases

Question 81

T/F spatial resolution is related to exposure amount

Answer 81

False

Question 82

The number of pixels sampled per mm as the laser scans each line of the imaging plate

Answer 82

Sampling frequency

Question 83

Increasing the sampling frequency results in the laser moving in a smaller distance and ________ spatial resolution

Answer 83

Increases

Question 84

The relationship between the sampling frequency and spatial resolution

Answer 84

Nyquist frequency

Question 85

What is the minimum rate at which a signal can be sampled without producing errors?

Answer 85

2x

Question 86

If 10 pixels/mm are scanned, Nyquist frequency is a maximum of:

Answer 86

5 lp/mm

Question 87

Results from x-ray deposition of energy in a detector

Answer 87

Signal

Question 88

A series of exposure values used to produce an acceptable image. It is the lightest light to the darkest darks that can be seen.

Answer 88

Dynamic range

Question 89

Greater dynamic range will yield greater:

Answer 89

Contrast resolution

Question 90

Ability of a system to both over and under expose yet still produce an acceptable image.

Answer 90

Exposure latitutde

Question 91

_______ is a range within the dynamic range

Answer 91

Exposure latitude

Question 92

Results from extaneous information and limits the ability to visualize objects

Answer 92

Noise

Question 93

Results when too few x-rays reach the IR

Answer 93

Quantum noise

Question 94

Increased __________ results in decreased noise

Answer 94

Intensity

Question 95

An increased SNR = a/an _________ in visbility spatial resolution

Answer 95

Increase

Question 96

What image information is required for legal considerations?

Answer 96

Name and ID number Markers Exam date Hopsital/clinic name where exam was performed

Question 97

A minimum mAs change of ___% is necessary to yield a noticeable RE change

Answer 97

30%

Question 98

Where will grid cutoff take place when using a grid outside the established focal range?

Answer 98

Lead strips on both lateral edges

Question 99

Where will grid cutoff take place when there is lateral decentering to a focused grid angulation?

Answer 99

Strips of more frequency one side more than the other

Question 100

Where will grid cutoff take place if a reciprocating grid is stopped during the exposure?

Answer 100

Uniform appearance of lead strips across the entire image

Question 101

Where will grid cutoff take place if a grid is placed upside down?

Answer 101

Complete cutoff towards both ends of the image

Question 102

Where will grid cutoff take place if a grid is placed off-level?

Answer 102

Lead strips across the entire image

Question 103

A wave-like or watery appearance of an image is referred to as:

Answer 103

Moire pattern

Question 104

When does the Moire pattern occur?

Answer 104

When two linear grids are placed on top of each other and the lead lines are not aligned at right angles with one another

Question 105

The moire pattern may occur with digital subtraction images if there is a misalignment of:

Answer 105

Pixels

Question 106

How does the Moire pattern occur in CR?

Answer 106

Laser light in CR reader runs parallel with the area of the grid lines

Question 107

How can the Moire pattern be avoided in CR?

Answer 107

Use a grid frequency of at least 60 lines per cm

Question 108

Image magnification is increased by:

Answer 108

Long OID Short SID

Question 109

What is the best way to minimize magnification?

Answer 109

Short OID (longer SID will result in a greater entrance exposure to the patient)

Question 110

What causes shape distortion?

Answer 110

Angulation of the tube, part, IR, and motion

Question 111

What causes a ghost image?

Answer 111

Insufficient erasure of an image