Physics Chapter 26 Density

Front 1

Along with contrast allows detail to be seen

Back 1

Density

Front 2

Degree of blackening from black metallic silver deposition on film

Back 2

Film density

Front 3

Adjustable component at the monitor, represents how much light is being emitted from the monitor, window level, changes overall lightness and darkness of image

Back 3

Brightness

Front 4

To much density is ___, to much information recorded, to much penetration, to bright or light

Back 4

Overexposed

Front 5

To little density is ___, to much beam attenuation, diagnostic info did not reach IR

Back 5

Underexposed

Front 6

Multiple variables influence __ thereby influencing image __

Back 6

Exposure, density

Front 7

Primary adjustor, exposure determines density, directly proportional, controls density,

Back 7

mAs

Front 8

As mAs goes __ exposure goes __ proportionally, so density goes __

Back 8

Up, up, up

Front 9

Digital is always a __ relationship

Back 9

Linear

Front 10

Film is linear only along the __ part of the D log E curve only

Back 10

Straight line

Front 11

mAs reciprocity

Back 11

Exposure=intensity x time

Front 12

Intensity of exposure

Back 12

mA

Front 13

Length of exposure

Back 13

Time

Front 14

Depends on exposure but independent of the components

Back 14

Density

Front 15

Interchange __ and ___ as long as __ is the same, ___ will be the same

Back 15

mA, time, mAs, density

Front 16

Occurs at extremely short or long exposure, inadequately calibrated equipment

Back 16

Reciprocity failure

Front 17

The 30% guideline is for __ only

Back 17

Film

Front 18

Why do you have to change mAs by at least 30% on film

Back 18

Can only see a visible change after changing mAs by 30%

Front 19

Why does the 30% guideline not apply to digital

Back 19

The histogram will control small to fairly large density adjustments

Front 20

If density needs adjustment on film what do you do

Back 20

Double the mAs to make darker, cut mAs in half to make lighter, anything less image does not need repeating

Front 21

With digital systems typically mAs adjustments will only need to be ___ to correct quantum mottle

Back 21

Increased

Front 22

On digital what will tell you if technique can be decreased next time around

Back 22

EI#

Front 23

If kVp goes up, scatter goes __, so density goes __

Back 23

Up, up

Front 24

If kVp goes up, penetrability goes __, so density goes __

Back 24

Up, up

Front 25

If kVp goes up,# of interactions at the target goes __, so __ xray photons are produced (quantity)

Back 25

Up, more

Front 26

Affects quantity and quality

Back 26

kVp

Front 27

Preferred method for density adjustments is through

Back 27

mAs

Front 28

Non linear relationship between a change in __ and __

Back 28

kVp, density

Front 29

Increase the kVp by 15% to double exposure to the IR, and cut mAs in half, will affect image contrast, influenced by tissue type, *more effectively use when a change in contrast is needed

Back 29

15% rule

Front 30

What kVp range does the 15% rule work best

Back 30

60-100 kVp

Front 31

With the same technique if a large focal spot is used and then a small focal spot what should not change

Back 31

Density

Front 32

What side of the is beam intensity greater

Back 32

Cathode

Front 33

This describes the change in exposure intensity when distance change

Back 33

Inverse square law

Front 34

change SID but keep same exposure what do you use

Back 34

Direct square law

Front 35

Going from 40" to 56" what would you do to mAs

Back 35

Double

Front 36

From 72" to 56"

Back 36

Halve

Front 37

From 40" to 72"

Back 37

Double then double again, should put exposure with in 50% range of pervious

Front 38

This type of filtration reduces exposure by eliminating soft xrays

Back 38

Inherent/added

Front 39

Type of filter that affects IR exposure and therefore density

Back 39

Compensating

Front 40

As beam restriction increases (FOV gets smaller) IR exposure will __

Back 40

Decrease

Front 41

Will reduce the number of photons, reduce scatter and patient dose

Back 41

Collimating

Front 42

Affects beam attenuation, inverse relationship with density, non linear relationship with density

Back 42

Tissue thickness, atomic #, tissue density (amount of atoms in area)

Front 43

Radiopaque like Ba or I, positive or negative contrast

Back 43

Positive

Front 44

Radiolucent like air or gas, positive or negative contrast

Back 44

Negative

Front 45

__ has similar effective atomic # as fat and water

Back 45

Air

Front 46

Larger tube angles create __ parts

Back 46

Thicker

Front 47

What absorbs scatter

Back 47

Grids

Front 48

The characteristics of IRs such as phosphor sensitivity will influence photon energy absorption and therefore IR __

Back 48

Exposure (and density)

Front 49

With digital post processing has a greater influence on what you __

Back 49

See

Front 50

With film what indicates how much xray energy is needed to achieve an exposure for a given speed cassette

Back 50

Speed numbers

Front 51

Film density will also be affected by (this is most overlooked)

Back 51

Processor chemicals

Front 52

Developer concentration to high, film in developer to long, developer temp to high

Back 52

Increased film density

Front 53

Processor chemicals contaminated, and become less effective

Back 53

Decreased density

Front 54

With digital what indicates how much exposure the IR received

Back 54

EI#

Front 55

There is greater __ with digital

Back 55

Latitude

Front 56

Enough __ is needed for the computers __ to adjust the information into the visible range

Back 56

Exposure, histogram