Radt B3B Radiographic Contrast

Front 1

Radiographic Contrast PP 2

In terms of acquiring contrast, what is film/screen dependent on?

Back 1

Film/screen is dependent upon the distribution of AG halide crystals.

Front 2

Radiographic Contrast PP 2

In terms of acquiring contrast, what is a digital imaging dependent upon?

Back 2

Digital imaging is dependent upon processing algorithm (organ code)

Front 3

Radiographic Contrast PP 2

What scale does the film/screen utilize?

(a) long and short scale

(b) gray scale

Back 3

(a) Long and short scale.

Front 4

Radiographic Contrast PP 2

What scale does digital imaging utilize?

(a) long and short scale (b) gray scale

Back 4

(b) gray scale

Front 5

Radiographic Contrast PP 2

In digital imaging, what component of the digital system deals with the overall contrast/scale?

Back 5

Bit depth/voxel.

Front 6

Radiographic Contrast PP 2

Where does the data come from/stored in digital imaging?

Back 6

Pixel.

Front 7

Radiographic Contrast PP 2

What components does the matrix include?

Back 7

Columns/rows.

Front 8

Radiographic Contrast PP 3

Describe all that you know about a long scale image?

Back 8

• Utilizes High kVp.

• Many shades of grays.

• Decreased differences in the tones.

• Lower contrasted image.

• More blended image.

Front 9

Radiographic Contrast PP 3

Describe all that you know about a short scale image?

Back 9

• Usually utilizes low kVp.

• usually for images with high contrast.

• Increased differences in the tones.

• Fewer shades of grays.

• Less blended image.

Front 10

Radiographic Contrast PP 5

Classify these procedures/examinations into either short scale/high contrast or long scale/low contrast.

• Iodinated contrast exams such as an IVU.

• extremity exams

• KUB

• Adult PA/lat CXR

• barium enema

• angiography of the upper extremity

• hypersthenic patient

• pelvis exam

Back 10

Long scale/Low contrast:

• KUB

• adult PA/Lateral chest x-ray

• hypersthenic patient

Short scale/high contrast:

• Iodinated contrast exam such as an IVU

• extremity exams

• barium enema

• angiography of the upper extremity

• pelvis exam

Front 11

Radiographic Contrast PP 5

What can be said about the pelvis exam as compared to an extremity examination versus a KUB?

Back 11

A pelvis exam is a longer scale/ lower contrast than an extremity exam.

It is higher contrast/Shorter scale it's compared to a KUB.

Front 12

Radiographic Contrast PP 6

For a fixed digital receptor, Is the response linear or not with the histogram? Yes or no?

If not explain why?

If yes, explain why?

Back 12

Yes.

In comparison it to this since it's a metric curve, digital imaging histogram devise a wider latitude or grayscale.

Front 13

Radiographic Contrast PP 6

What does the Y axis of the histogram represent?

Back 13

Quantity of OD or number of pixels.

Front 14

Radiographic Contrast PP 6

What does the X axis of the histogram represent?

Back 14

LRE: Log relative exposure.

Front 15

Radiographic Contrast PP 6

(a) As we move to the right of the historgram, what type of densities will we acquire?

(b) As we move to the left?

Back 15

(a) Higher/Darker Densities.

(b) Lower Densities.

Front 16

Radiographic Contrast PP 8

T/F: Receptor contrast (Digital) it Is limited by contrast resolution.

Back 16

True.

Front 17

Radiographic Contrast PP 8

T/F: In digital imaging, contrast resolution is determined by the dynamic range of the system.

Back 17

True.

Front 18

Radiographic Contrast PP 8

What is the relationship between contrast and the window width?

Provide examples.

Back 18

INVERSELY RELATED.

Wide window: lower contrast.

Narrow window: higher contrast.

Front 19

Radiographic Contrast PP 8

T/F: Digital imaging has an algorith that allows for the system to have a narrower dynamic range if compared to film/screen technology.

Back 19

FALSE.

Digital has a wider dynamic range than filmscreen.

Front 20

Radiographic Contrast PP 9

In film/screen, to acquire a faster speed what size phosphors should be utilized?

Back 20

Thicker and Larger phosphors.

Front 21

Radiographic Contrast PP 9

Which portion of the sensitometric curve determinants contrast?

Back 21

Straight-line portion.

Front 22

Radiographic Contrast PP 9

What does the sensitometric/ characteristic curve look like for filmscreen technology? Briefly describe the components.

Back 22

It is curved. Toe, Shoulder, Straightline portion that determines contrast.

Front 23

Radiographic Contrast PP 9

(a) What happens to the slope of the sensitometric curve when contrast increases?

(b) What happens to the slope of the sensitometric curve when latitude widens?

Back 23

(a) The slope becomes steeper

(b) Less steep/more horizontal.

Front 24

Radiographic Contrast PP 9

(a) What happens to the slope of the sensitometric curve when contrast decreases?

(b) What happens to the slope of the sensitometric curve when latitude narrows?

Back 24

(a) The slope becomes horizontal/less steep.

(b) Steeper.

Front 25

Radiographic Contrast PP 10

What is differential absorption?

Back 25

Interaction with matter.

Tissues having differential absorption of radiation due to their different absorption characteristics. The

Front 26

Radiographic Contrast PP 10

In digital imaging, subject contrast is determined by what?

Back 26

It is determined by the signal differences in the remnant/exit x-ray beam and what actually gets to the IR.

Front 27

Radiographic Contrast PP 10

What two characteristics is subject contrast, in filmscreen, dependent upon?

Back 27

Dependent upon kVp and fog.

Front 28

Radiographic Contrast PP 11

When we increase kVp, what happens to...

• beam wavelength and energy

• been penetration

• production of Compton scatter and recording on IR

• range of OD seen on the IR

Back 28

• wavelength is shortened, energy increased.

• beam penetration increased

• scatter increases

ª darker OD on the IR; Increases shades of gray's widens the latitude, longer scale/lower contrast

Front 29

Radiographic Contrast PP 11

What are some causes of fog, define fog.

Back 29

Unwanted densities on the film.

Some causes of fog are;

• environmental radiation

• scatter radiation

• background radiation

• heat, age of film

• wrong detector

Front 30

Radiographic Contrast PP 13

What change in kVp is needed to affect a change in contrast for film/screen technology?

Back 30

4%

minimum between 50 to 90 kVp?

Front 31

Radiographic Contrast PP 15

When differential absorption is greater what happens to subject contrast and why?

Back 31

Increasing differential absorption changes the different densities (bone and tissues) that will absorb the x-ray beam Image of forming rays therefore subject contrast will increase.

We will be able to see and increase differences in the adjacent tissues and structures.

Front 32

Radiographic Contrast PP 15

Our structures more or less similar and subject contrast is lower? Why?

Back 32

More similar/blended. (Longer scale)

Less subject contrast, less differences in adjacent structures and parts.

Front 33

Radiographic Contrast PP 15

Two KUB's are taken on the same patient, one with no added contrast material and one with added barium and air contrast media. What type of sound check contrast will each have on the IR?

Back 33

Barium/Air:

• Higher contrast/shorter scale

• Increases subject contrast.

KUB with no contrast media:

• Lower contrast/Longer scale

• Less subject contrast

Front 34

Radiographic Contrast PP 17

What happens to radiographic contrast when and 8:1 grid is used instead of no grid on an AP projection of the knee?

Back 34

8:1Grid: Increased contrast.

No Grid: Reduced Contrast.

Why? more absorption of the scatter radiation.

Front 35

Radiographic Contrast PP 17

What happens to radiographic contrast when collimation is reduced on a fully exposed 10×12 IR to 9×10 x-ray beam?

Back 35

9x10: Higher contrast

• less scatter radiation

• more detail, higher scale of contrast

• reduced FV

10x12: Lowered contrast

Front 36

Radiographic Contrast PP 17

What happens to image contrast when an air gap technique was used for a chest x-ray?

Back 36

Increased image contrast due to technique preventing scatter reaching the IR.

Front 37

Radiographic Contrast PP 17

What happens to image contrast when you compare a normal chest x-ray versus an advanced case of pneumonia on a chest x-ray?

Back 37

Normal Chest X-Ray: Higher contrast in comparison to the pathology exam due to the fact that we increase our kVp for an additive pathology.

With additive: kVp increases, more scatter = washed out/blended/grays

Front 38

Radiographic Contrast PP 19

What happens to radiographic contrast when quantum noise increases on digital images?

Back 38

Radiographic contrast is reduced due

• to mottley,

• lack of detail

• and reduced differences in the tones.

Front 39

Radiographic Contrast PP 19

What happens to radiographic contrast when an IP saturation occurs?

Back 39

Reduced radiographic contrast will result because there will be an increase abnormal amounts of black densities which leads to loss of detail and contrast.

Front 40

Radiographic Contrast PP 19

What happens to image contrast if ambient light is decreased for CR DR images?

Back 40

Increase contrast,

decreases the glare, increases the detail, defines the differences in tones.

Front 41

Radiographic Contrast PP 19

Taking into account the same field of view, what happens to radiographic contrast when a 1024x1024 matrix is used instead of a 512x512?

Back 41

INCREASED RESOLUTION.

There'll be more contrast due to more data and more pixels;