Chapter 1 (pages 38-47)

Question 1

When making an image, exposure factors must be picked with what variables?

Answer 1

Density of part/anatomic number
Thickness of the anatomical part
Pathology
Technology being used

Question 2

What are technique factors?

Answer 2

kVp and mA

Question 3

Image Quality Factors (analog)

Answer 3

Density
Contrast
Spatial Resolution
Distortion

Question 4

What is the primary controlling factor for RE?

Answer 4

mAs

Question 5

What is the secondary controlling factor for RE?

Answer 5

SID

Question 5

Relationship between RE and mAs

Answer 5

Direct Proportional

If you double the mAs, you double the amount of x-rays

Question 5

Other factors that affect the RE (analong)

Answer 5

kV, part thickness, chemical time, chemical temp, grid ratios, and film screen speed

Question 6

What is the Anode Heel Effect?

Answer 6

Cathode side of the tube has more xrays being projected than the anode side, so the thicker side of the patient should go to the cathode side

FATCAT - fat side to cathode

Diaphragm is the thickest part of the abdomen

Question 7

What are examples of compenstating filters?

Answer 7

Boomerang (shoulder)
Ferlic filter (hips)
Wedge filters (chest, foot)

Question 8

What does a compensating filter do?

Answer 8

Filters out a portion of the primary beam toward the thin or less dense part of the body

Question 9

What causes an image to be underexposed and what will it look like?

Answer 9

Too little mAs - image will be very light

Question 10

What causes an image to be overexposed and what will it look like?

Answer 10

Too much mAs, image will be very dark

Question 11

What is contrast?

Answer 11

The difference in receptor exposure between adjacent areas

Question 12

What does long gray scale contrast look like?

Answer 12

Many, many shades of grey - hard to tell the difference between them (think of a paint strip)

Question 13

What does low contrast look like?

Answer 13

a large amount of adjacent grays. Difficult to tell the difference from one gray to the next. Needs a kVp # like 110

Question 14

In productions, what is the main controlling factor for contrast?

Answer 14

kVp

Digital images use kVp and LUT (look up tables)

Question 15

A high kVp will give what type of contrast?

Answer 15

Low contrast image - more gray colors

Question 16

A low kVp will give what type of contrast?

Answer 16

High contrast - more black and white

Question 17

What is the relationship between kVp and receptor exposure?

Answer 17

Direct - as you increase kVp, RE increases

Question 18

4 causes of grid cutoff

Answer 18

Off center - the center of your IR must be the same as the center of your focused grid

Off level - means your central ray is not at a good 90 degrees to the center of the grid

Off focus - this has to do with distance. Some grids only work for certain distances

Upside down focus - x-rays must be going in the same direction as the grid lines

Question 19

What is grid frequency?

Answer 19

The number of lead strips per inch or centimeter

Question 20

What is spatial resolution?

Answer 20

defined as the recorded sharpness of structures on an image

Question 21

Geometric controlling factors for spatial resolution (analog)

Answer 21

Focal spot size, SID and OID

A small focal spot results in less penumbra

The higher the SID, the better the spacial resolution

As OID decreases, spatial resolution increases

Question 22

What is motion on an image?

Answer 22

Blurring effect

Can be voluntary or involuntary

Question 23

What is the best way to control motion?

Answer 23

Short exposure time
Communication to the patient
Patient immobilization and controlled breathing

Question 24

What is distortion?

Answer 24

A misrepresentation of an object shape or size

Question 25

What has the least amount of beam divergence?

Answer 25

Central ray

Question 26

What are the 4 controlling factors of distortion?

Answer 26

SID - magnfication
OID - magnification
Object-image alignment - foreshortening
CR alignment - elongated

Question 27

What are the 5 different tissue types from least dense to most

Answer 27

Air
Fat
Water
Muscle
Bone

Question 27

Current technology has a broader:

Answer 27

Exposure latitude (can edit pictures now that they are digital)

Question 28

What is short gray scale contrast?

Answer 28

Looks like very few shades of white, black, and gray

Question 29

What is high subject contrast?

Answer 29

A certain black and white look of an image.

Question 30

What is the kVp range for all body parts?

Answer 30

60-120. 130 will degrade the image

Question 31

What is foreshortening?

Answer 31

The object is not lined up correctly with the IR. Incorrect placement causes the object to look smaller.

Ex. both joints of long bones need to be on IR.

Question 32

How does central ray alignment affect distortion?

Answer 32

Central ray must be aligned with the object. The more beam divergance, the more distortion. Body part will look elongated

Question 33

Types of distortion

Answer 33

Magnification
Elongation
Foreshortening

Question 34

Another word for distortion?

Answer 34

Misrepresentation

Question 35

How much does SID need to increase for every 1” of OID

Answer 35

By a factor of 7

Question 36

How to fix grays when RE is optimal?

Answer 36

15% rule

Question 37

How to fix overpenetrated and overexposed

Answer 37

Decrease kVp

Question 38

How to fix underpenetrated and underexposed

Answer 38

Increase kVp

Question 39

How to fix overexposure or underexposure

Answer 39

Double or half mAs

Question 40

What is Air Gap Technique theory?

Answer 40

Increasing OID, reduces scatter - no need for a grid

Question 41

A 40” SID is how many cm?

Answer 41

100 cm

Question 42

What is needed in the filament cup to burn off electrons?

Answer 42

mA and current