Radiographic Density Flashcards Preview

Radiography Spring 2016 > Radiographic Density > Flashcards

Flashcards in Radiographic Density Deck (44):
1

Define Radiographic Density

Visibility of detail factor that describes the amount of blackness seen on an image (background blackness brightness indication)

2

What radiographic density is directly related to?

To quantity (amount) of radiation reaching IR

3

When sufficient radiographic density is achieved

When the bony and soft tissue structures of interest are visualized

4

What mAs is controlling factor of?

quantity or amount of radiation

5

What an increase and decrease in mAs will do to Radiographic Density (with adequate penetration)

increase= increase in Radiographic density
decrease= decrease in radiographic density

6

What excessive mAs demonstrates on image

Density that is so dark that some or all of bony and soft tissue structures of interest are not well visualized it will be too dark

7

How to determine between if too much mAs or kVp was used on a dark image

evaluating the image contrast

8

What an overexposed image using too much mAs demonstrates

acceptable contrast as long as kVp used is optimal

9

How an overexposed image using too much mAs will appear

overall dark, the cortical outlines of the bone should remain high in contrast

10

What an underexposed image using insufficient mAs demonstrates

Density that is so light that some or all of the anatomic structures cannot be seen or evaluated

11

How an underpenetrated (kVp) image will appear

image will not demonstrate the cortical outlines that were not penetrated

12

Controlling factor of image density

mAs

13

what 30% change in mAs will demonstrate?

adjusts the image density just enough for the eues to be able to visualize that a change was made

14

When is it ideal to use the 30% rule

when an image demonstrates acceptable but not optimal density and needs to be repeated because of a factor other than density (artifact, motion)

15

what will a change in mAs be on an image that is borderline too light

100% increase in mAs

16

what will a change in mAs be on an image that is borderline too dark

50% decrease in mAs

17

what will a change in mAs be on an image so light or dark it will have to be repeated

3-4 times the increase or decrease in mAs

18

How kVp affects radiographic density

is affected by a change in kVp because it alters the quality of photons

19

How mAs compensates for insufficient kVp if possible

NO AMOUNT

20

Define optimum kVp

kVp that will provide adequate part penetration and sufficient gray scale

21

How image that has been adequately penetrated will appear

demonstrates the cortical outlines of the thinnest and thickest bony structures of interest

22

what factor is automatically set with AEC

mAs

23

what factor technologist must set with AEC

optimum kVp level

24

Define minimum response time

the time it takes for the circuit to detect and react to radiation received

25

with reference to AEC what results in underexposed images

failure to properly activate correct ionization chambers and to not center the anatomic structure over them

26

when using the AEC why its important to use tight collimation

to reduce scatter radiation that may cause the AEC to shut off prematurely

27

what situations or conditions will prohibit you from using AEC

when any type of radiopaque hardware or prosthetic device will be positioned over activated chamber

28

What changes the 1 button and 2 button imply when using them for density control

1- 25% density change
2- 50% density change

29

What increasing SID does to radiographic density

decreases

30

what decreasing the SID does to radiographic density

increases

31

what is the % of change in SID for a visible density change

20%

32

how increasing OID affects density

could result in a noticeable density loss

33

what must be done to mAs when changing to a higher grid ratio and how this will affect density

increase mAs, or insufficient density

34

what must be done to mAs when changing to a lower grid ratio and how it affects mAs

decrease in mAs

35

How to distinguish grid cut off from other density problems

appearance of grid lines on the image

36

what the amount of density change depends on

field size and the amount of scatter that would typically reach IR

37

why compensating filter is used

to offset the thickness difference and obtain optimum density throughout entire images

38

how you should set your technique when using a compensating filter

set a technique that will adequately penetrate the thickest portion of the anatomic structure of interest

39

when you should use Anode Heel Effect

when positioning long bones and the vertebral column when a long 17" field length is used

40

which end produces more photons

cathode

41

when using anode heel effect what part of structure will be placed under anode end of the tube and cathode end of the tube

anode-thinner side of structure
cathode-thicker side of the structure

42

what part of tube represents + or - symbols

+= anode
- = cathode

43

how mAs should be set with anode heel effect

to adequately demonstrate the midpoint of structure (where CR will enter)

44

what using anode heel effect demonstrates on the finished image

a more uniform density across the part