Receptor Exposure (Density)

Question 1

Radiographic Properties

All radiographic properties must be in balance in order to create what?

Answer 1

Radiographic Properties

a “good” quality image.

Question 2

Two Categories of Radiographic Quality:

• What are the 2 categories of radiographic quality and what do they consist of?

Answer 2

Two Categories of Radiographic Quality:

Categories = photographic properties and geometric properties

• Photographic properties consist of: receptor exposure (brightness or radiographic density) and gray scale (contrast)
• Geometric properties consist of: spatial resolution (detail or sharpness of lines) and distortion

Question 3

Quality Image must have:

What 4 things should a quality image have?

Answer 3

Quality Image must have:

1. Minimum distortion
2. Maximum sharpness of structural lines
3. Proper gray scale or correct gray tones on image
4. Sufficient radiation exposure to visualize body part (receptor exposure or brightness level - not too light or too dark)

Question 4

Receptor Exposure / Density

Receptor exposure is what type of base system? Describe.

Density is what type of base system? Describe.

“Overall ___ of a radiographic image”

Answer 4

Receptor Exposure / Density

Receptor exposure = Digital base system = brightness of the image as viewed on the monitor

Density = Film base system = degree of blackening of radiograph due to accumulation of black metallic silver on the radiographic film

“Overall darkening of a radiographic image”

Question 5

What’s wrong with the image? How would you change it to make it better?

Answer 5

What’s wrong with the image? How would you change it to make it better?

A little too light. Change mAs by 30%

Question 6

What’s wrong with the image? How would you change it to make it better?

Answer 6

What’s wrong with the image? How would you change it to make it better?

Too dark. Make it lighter. 1/2 mAs.

Question 7

What would determine how you would change this image?

Answer 7

What would determine how you would change this image?

What part you’re looking at –

If looking at chest - too dark

If looking at abdomen - too light

Question 8

What’s wrong with the image? How would you change it to make it better?

Answer 8

What’s wrong with the image? How would you change it to make it better?

Too light. Go up 30% minimum.

Question 9

What’s wrong with this image?

Answer 9

​What’s wrong with this image?

Too dark and too black-white

• Oversaturation

Question 10

Contrast or Gray Scale

What is contrast or gray scale?

Answer 10

Contrast or Gray Scale

• Visible differences between any two selected areas of density within the radiographic image.
• “Differences in shades of density”

Question 11

Contrast

What kind of scale is this?

Answer 11

Contrast

Short scale - abrupt changes

Question 12

What kind of contrast level is demonstrated in the image?

Answer 12

What kind of contrast level is demonstrated in the image?​

Low scale contrast - don’t see a lot of differences

Question 13

What kind of contrast level is demonstrated in the image?

Answer 13

What kind of contrast level is demonstrated in the image?

Low contrast scale - no proper gray scale

Question 14

What kind of contrast level is demonstrated in the image?

Answer 14

What kind of contrast level is demonstrated in the image?

Low contrast scale - too black and white - not enough gray scale

Question 15

What kind of contrast level is demonstrated in the image?

Why?

Answer 15

What kind of contrast level is demonstrated in the image?

High contrast scale - because has barium - much more white

Question 16

Contrast

Anytime you have ___, it’s a higher contrast scale because of ___ on image.

Answer 16

Contrast

Anytime you have contrast, it’s a higher contrast scale because of white on image.

Question 17

What’s wrong with this image? How could it be fixed?

Answer 17

What’s wrong with this image? How could it be fixed?

Too gray

Can change kVp, or use a grid

Question 18

Recorded Detail

What is recorded detail?

What are other names used for recorded detail?

Answer 18

Recorded Detail

Recorded detail = sharpness of structural lines on radiographic image

Other names used = detail, sharpness of detail, definition, spatial resolution

Question 19

Recorded Detail

What’s wrong with this image?

Answer 19

Recorded Detail

Recorded detail lost

Question 20

Which image has better detail?

Answer 20

Which image has better detail?

Left

Right has lost detail

Question 21

Distortion

What is distortion? What are some examples of distortion?

Anything we ___ or ___ is distortion.

Answer 21

Distortion

Distortion = misrepresentation of shape or size of a structure recorded on image

Example = foreshortening, elongation, magnification

Anything we rotate or oblique is distortion.

Question 22

Receptor Exposure / Density

What is receptor exposure/density dependent on?

What measures the radiographic density on a film? How?

Using digital imaging, receptor exposure can be indicated by what?

Answer 22

Receptor Exposure / Density

Receptor exposure/density dependent on amount of radiation received by IR/film

Densitometer measures radiographic density on a film - by comparing incident light to transmitted light

Using digital imaging, receptor exposure can be indicated by dose index numbers

Question 23

Human Visibility

What is the optical density range for humans?

Answer 23

Human Visibility

0.25 - 2.50

Question 24

Digital Radiography Terms for Density

What is brightness?

What does window level describe?

Answer 24

Digital Radiography Terms for Density

Brightness = the same concept of density but it is displayed on a soft-copy monitor.

Window Level = describes the digital processing that produces changes in density/brightness.

Question 25

Effects on Image Appearance

What makes radiography an art, not an exact science?

“____” for changes in technical factors are guidelines. Sometimes they only apply to a range of ___.

Answer 25

Effects on Image Appearance

Variables make radiography an art, not an exact science

“Rules” for changes in technical factors are guidelines. Sometimes they only apply to a range of circumstances.

Question 26

Factors Affecting Density

Controlling or Influencing

___ controlling factor

• Multitude of ___ factors
• mAs reciprocity*
• Failure
• Short exposure times of < than ___ seconds
• Long exposures times of > than a ___ seconds

Answer 26

Factors Affecting Density

Controlling or Influencing

mAs controlling factor

• Multitude of influencing factors
• mAs reciprocity*
• Failure
• Short exposure times of < than 0.01 seconds
• Long exposures times of > than a few seconds

Question 27

MAJOR CONTROLLING FACTOR OF DENSITY

What is the major controlling factor of density? What does it control?

Answer 27

MAJOR CONTROLLING FACTOR OF DENSITY

Major controlling factor of density = mAs

Controls = amount of radiation produced by controlling amount of electrons flowing across X-ray tube

Question 28

Digital Radiography

What does the window level control?

What is critical in determining proper digital image receptor exposure?

Answer 28

Digital Radiography

Window Level will control the density level

Setting the correct mAs is still critical in determining proper digital image receptor exposure.

Question 29

mAs

mAs and what are directly proportional?

What does that mean?

Ex) The radiologist wants you to repeat a knee film that is double the darkness it should have been. You used 60 kVp at 6 mAs.
What do you do? Film was too dark - how much?

Answer 29

mAs

• mAs and density are directly proportional
• Meaning in order to double the density on the radiographic image, you will double the mAs value
• In order to half the density on the radiographic image, you will half the mAs value.

Ex) The radiologist wants you to repeat a knee film that is double the darkness it should have been. You used 60 kVp at 6 mAs.
What do you do? Film was too dark - how much?

Double dark so cut the mAs in half.

6 mAs divide by 2 = 3 mAs

Question 30

Minimum change for mAs in order to see a change:

What rule is used/what do you change your mAs value by to see a change in density?

Answer 30

Minimum change for mAs in order to see a change:

30% rule for mAs value to see change in density

50 mAs x .30 = 15 mAs
You must add 15 mAs to your mAs value in order to see your film become darker.

You must subtract 15 mAs from you mAs value in order to see your film become lighter.

Question 31

Influencing Factors:

What do influencing factors influence? What will change if influencing factors change?

Answer 31

Influencing Factors:

Influencing factors influence density.

If influencing factors change, density changes

Question 32

Kilovoltage

What does kVp control?

• ___ ___ of the beam
• Changes in kVp alter ___ of the beam
• Production of ___ ___ is affected by the kVp
• Patient’s ___ ___

Answer 32

Kilovoltage

kVp controls energy (strength and wavelength) of the electrons

• Penetration power of the beam
• Changes in kVp alter intensity of the beam
• Production of scatter radiation is affected by the kVp
• Patient’s radiation dose

Question 33

Minimum Change in Density using kVp

What rule is used/what do you do to your kVp in order to see a minimum change in density?

Answer 33

Minimum Change in Density using kVp

In order to see a minimum changes in density you must change your kVp by 10%.

50 kVp at 5 mAs and the film was a little light.

50 x .10 = 5

You must use 55 kVp in order to make the film a little darker.

Question 34

Double or Half the Density using kVp

What rule is used/what do you do to your kVp in order to double or half the density?

Answer 34

Double or Half the Density using kVp

In order to double or half the density, you must change kVp by 15%

60 kVp at 12 mAs film was double dark.
60 x .15 = 9 kVp
60 -9 —New kVp=51 kVp

Question 35

Why not use kVp to change density?

Answer 35

Why not use kVp to change density?

Because it also changes

• Wavelength
• Penetration power of the beam
• Patient radiation dosage
• Scale of contrast

Question 36

Anode Heel Effect

___ varies along the ___ ___ of the ___

What does the anode heel effect do?

Density up to ___% greater at the ___ side of the beam

Anode side = ___ intense

Cathode side = ___ intense

Where do we want thicker body parts?

Answer 36

Anode Heel Effect

Intensity varies along the long axis of the beam

The anode heel effect alters the intensity of the beam across the cathode/anode axis

Density up to 45% greater at the cathode side of the beam

Anode side = less intense

Cathode side = more intense

Where do we want thicker body parts? Cathode end

Question 37

Source-Image-Distance (SID)

What does the inverse square law state?

What is inversely proportion to the square of the distance?

Shorter SID = ___ film AND Longer SID = ___ film (if same technique is used)

Answer 37

Source-Image-Distance (SID)

Inverse square law states that the intensity of the beam varies with the distance from the source of radiation.

Exposure is inversely proportion to the square of the distance

Shorter SID = darker film AND Longer SID = lighter film (if same technique is used)

Question 38

Inverse Square Law vs New Mas Formula

What is inverse square formula?

What is the new mAs formula to maintain density?

Answer 38

Inverse Square Law vs New Mas Formula

Inverse Square Formula:

• Old Intensity = New Distance²
• New Intensity = Old Distance²

To Maintain Density: New mAs Formula

• Old mAs x New Distance²
• Old Distance²

Question 39

Rules for SID Changes:

• Look for ___
• If SID doubles = ___ x mAs
• If SID is cut in half = ÷ mAs by ___
• Rule of Thumb:
• 40” to 72” = ___ x mAs
• 72” to 40” = ÷ mAs by ___

Answer 39

Rules for SID Changes:

• Look for doubles
• If SID doubles = 4 x mAs
• If SID is cut in half = ÷ mAs by 4
• Rule of Thumb:
• 40” to 72” = 4 x mAs
• 72” to 40” = ÷ mAs by 4

Question 40

Object to Image Receptor Distance OID

What is an air gap grid?

Shorter OID = ___ film AND Longer OID = ___ film (if same technical factors are used)

Answer 40

Object to Image Receptor Distance OID

Air gap grid = the air space between the part and IR acts as a grid

so:

Shorter OID = darker film AND Longer OID = lighter film (if same technical factors are used)

Question 41

Filtration

What does filtration do and why?

Increase filtration = ___ film AND Decrease filtration = ___ film (if same technical factors are used)

Answer 41

Filtration

Filtration removes longer wavelengths so that less radiation leaves the tube

Increase filtration = lighter film AND Decrease filtration = darker film (if same technical factors are used)

Question 42

Beam Restriction “Collimation”

What do you cut off when you cone down?

smaller field side = ___ film VS larger field size = ___ film (if same technical factors are used)

Answer 42

Beam Restriction “Collimation”

What do you cut off when you cone down? Primary radiation field

smaller field side = lighter film VS larger field size = darker film (if same technical factors are used)

Question 43

Anatomical Parts

Attenuation is the ___ in the number of ___ as they travel through the body ___.

smaller body parts = ___ film VS larger body parts = ___ film (if same technical factors are used)

Answer 43

Anatomical Parts

Attenuation is the decrease in the number of photons as they travel through the body thickness.

smaller body parts = darker film VS larger body parts = lighter film (if same technical factors are used)

Question 44

Grids

What do grids do?

Grid = ___ film VS Nongrid = ___ film (if same technical factors are used)

Rule of Thumb:

• Non-Grid to Grid = ___ x mAs
• Grid to Non-Grid = ÷ mAs by ___

Answer 44

Grids

Grids remove scatter radiation from striking film (less radiation reaching film)

Grid = lighter film VS Nongrid = darker film (if same technical factors are used)

Rule of Thumb:

• Non-Grid to Grid = 4 x mAs (too light)
• Grid to Non-Grid = ÷ mAs by 4 (too dark)

Question 45

Film/Screen Combinations

You will need to remember the ___, ___, and ___ of thefilm/screen.

faster the system = ___ film VS slower the system = ___ film (if same technical factors are used)

Answer 45

Film/Screen Combinations

You will need to remember the size, thickness, and speed of thefilm/screen.

faster the system = darker film VS slower the system = lighter film (if same technical factors are used)

Question 46

Film Processing

You must process the film using the requirement of the ___. If you change the ___ of the developer or length of the ___ you will notice a change in the ___.

• Hotter Temp= ___ Film VS Cooler Temp = ___ film
• Longer Time= ___ Film VS Shorter Time = ___ film

Answer 46

Film Processing

You must process the film using the requirement of the manufacturer. If you change the temperature of the developer or length of the time you will notice a change in the density.

• Hotter Temp= Darker Film VS Cooler Temp = lighter film
• Longer Time=Darker Film VS Shorter Time = lighter film

Question 47

Quick Tip:

If less radiation is produced or less radiation is reaching the IR, the overall brightness/density will ___.

If more radiation is produced or more radiation is reaching the IR, the overall brightness/density will ___.

Answer 47

Quick Tip:

If less radiation is produced or less radiation is reaching the IR, the overall brightness/density will decrease.

If more radiation is produced or more radiation is reaching the IR, the overall brightness/density will increase.