This document contains a series of images and text from a lab test on density, contrast, distortion, and detail in radiography. It demonstrates how various technical factors like kVp, mAs, filtration, grid use, and collimation can affect the density, contrast, and detail visible on the radiographic image. Specifically, it shows that density increases with higher mAs, decreases with more filtration or a grid, and is inversely related to SID, tissue thickness, and collimation. Contrast is maximized at an intermediate kVp and is highest with less collimation, no grid, and optimal kVp and mAs. Detail decreases with more motion, tissue thickness, focal spot size

1. Density, Contrast, Distortion &
Detail
Lab Test #3

2. Contrast and the 15% Rule
Objective: To

demonstrate the
influence of the 15%
rule on contrast
1st exposure at

recommended
technique
Used as control


3. Contrast and the 15% rule
Apply the 15% rule

twice and ↑ kVp ↓ mAs
accordingly
All other factors stay the

same
The math doesn’t quite

add up on this one, so I
think the images are from
2 different groups

4. Contrast and the 15% rule
Again, this image doesn’t

match my lab sheet, I
believe we lowered the kVp
15% and shot another on
just for S&G
At this point, we should

compare the 2 images to
determine which has the
longest scale of contrast
See next slide


5. Contrast and the 15% rule
Low kVp=High Contrast= Short scale High kVp=Low Contrast= Long scale
More B&W More Shades of Gray

6. Density- Control Image
Objective: To

demonstrate the effect
of select factors on
density
Control image of knee

phantom taken @
5mAs, 60kVp, & 40”
SID.

7. Density- Filter
With no change in tech

factors, a copper sheet
is taped to the face of
the collimator
Filters have an inverse

relationship on density
thus:
↑ Filtration ↓ Density


8. Density- Grid
Copper filter removed

No change in technical

factors
Grid is introduced to IR

Result: Adding a grid

decreases density this
is an inverse
relationship
(+) ↑ Grid ↓Density


9. Density- SID
Grid removed

No change in technical

factors
SID increased from 40”

to 60”

10. Density-Tissue Thickness
Grid is removed and hand

phantom is substituted for
knee
No change in technical

factors
Overall, the hand the tissue

thickness of the hand is
much less than that of the
knee
↑ tissue thickness ↓density


11. Density- Collimation-Control
Torso phantom is

substituted for hand
14x17 collimation

Use technique

recommended by
console + 20 mAs
This image will be

compared with the
highly collimated
image.

12. Density- Collimation
Collimation is

increased to a 4x4
square.
Repeat exposure of

torso with no change in
technical factors
↑collimation ↓density


13. Density- Anode Heel Effect
Use a foot phantom

and a 14x17 cassette
2 mAs, 60 kVp, 40” SID

Leave collimation open

lengthwise to 17”
Orient toes over the

anode side

14. Density- Anode Heel Effect
All technical factors remain the

same
Foot is moved to opposite end of

cassette to place toes on
cathode side
In practice, the thickest tissue

should be placed at the cathode
end of tube
In theory, placed thicker tissue at

anode end would effect density
A visible change in density would

only be appreciated with
film/screen

15. Size Distortion: Control
Objective: To

demonstrate the
various types of
distortion
Control image of hand

shot at 40” SID
Technique: Pre-

programmed

16. Size Distortion: 6” OID
2nd image

6” OID is created with

sponges
All other factors remain

the same
Compare with control

image to note distortion
(magnification)

17. Size Distortion: 12” OID
Image #3

OID is ↑ to 12”

Collimation is exactly the

same
No other factors have

been changed
Note magnified

appearance of hand
Such distortion can mask

pathology

18. Distortion: OID + SID
OID is ↓ to 6”

SID is ↓ to 20”

All remaining tech factors

are unchanged
Result: Size distortion

(magnification in this
case) can be caused by
OID, SID or both

19. Shape Distortion: Control
Control exposure of

knee phantom
w/recommended tech
factors
This image will be used

for comparison with
others

20. Shape Distortion: Angled Tube
2nd image of knee

phantom
Tube is angled

All tech factors remain

the same

21. Shape Distortion: Angled IR
3rd exposure of knee

phantom
IR is angled

All tech factors are

unchanged from
control
Note closed joint

spaces

22. Shape Distortion: Angled Anatomy
4th exposure of knee

phantom
All tech factors remain

constant except…
Phantom is angled

Result: Shape distortion

can be caused by the
angulation of tube, IR or
anatomy being imaged.

23. Density & mAs
Objective is to

demonstrate the effects
of overexposure &
underexposure on CR
images
First image is made @

60kVp, 10mAs w/40”
SID

24. Density & mAs 2
mAs is ↑ 50

All other technical factors

remain the same
LGM#’s of all images will be

compared with control
LGM represents the # of

photons reaching IR to form
the latent image
LGM is proportional to mAs


25. Density & mAs 3
↑ to 100 mAs

No other technical

factors are changed
At this stage, LGM#’s

appear to be ↑ as mAs is
↑ (a direct relationship).

26. Density & mAs 4
↑ to 200 mAs

Remaining tech factors

unchanged
LGM#’s increase with

each increase in mAs
mAs is THE controlling

factor of density

27. Detail and Distortion: Motion
Objective: To demonstrate

the effect of motion on
detail
Technical factors: The

programmed technique for
a foot but ↓ mA
Decrease in mA is necessary

to ↑ exposure time
(applicable in next image)
1st image of top taken on

10x12 w/no motion

28. Detail and Distortion: Motion
2nd image- top is

spinning while
exposure is taken
Technical factors are

unchanged
The lower mA ↑

exposure time, allowing
the motion to be caught
on film

29. Detail and Distortion: Motion
Additional image of this

experiment
Compared to the 1st image

(stationary), the lead letter
attached to top is blurred.
Result: Increased motion

decreases detail
Motion↑↓ Detail

Although motion is generally a

detriment to good films, it can be
used to the RT’s advantage
Ex: Using breathing technique to

blur ribs

30. Quantum Mottle
Definition: a lack of

sufficient incoming data
to process an image;
AKA quantum noise
No idea what this

image has to do with
anything, but that’s
how it was labeled
That would be a cool

name for a band
though

31. Contrast- Control Image
Objective: To

demonstrate how
selected factors effect
contrast
66kVp, 10 mAs, 40”

SID on table top

32. Contrast 66kv
Skull phantom is

replaced w/step wedge
Exposure taken with no

changes in technical
factors
Compare this image

w/second exposure
using a higher
technique

33. Contrast: ↑kVp ↓mAs
↑ to 86kVp

Compensate by ↓mAs to

¼ of its original value
All other factors remain

the same

34. Contrast- 86kv
Again, step wedge

takes the place of skull
phantom
No change in technical

factors
Compare shades of

gray in adjacent
densities

35. Comparison of Contrast
Low kVp High kVp

36. Contrast: +Grid
3rd image of skull

Grid is introduced

mAs ↑ 4x to

compensate
All remaining factors

unchanged

37. Contrast: Scatter
4th image of skull

Collimation open wide

to expose IR to scatter
All remaining factors

unchanged
Compare this series of

images to note
differences in adjacent
densities

38. Contrast Collimation
Skull is now positioned

laterally
This exposure will use

bucky instead of table
top
100 kVp @ 20mAs


39. Contrast: Collimation
Repeat exposure of

lateral skull
Collimated to 3”x3”

area
All remaining factors

are unchanged

40. Short vs Long Scale Contrast: kVp
Objective: To

demonstrate short &
long scale contrast
Elbow phantom @

46kVp & 5mAs

41. Stepwedge 2 Contrast ????
I think this is supposed

to be part of a contrast
lab but I couldn’t match
it up with anything
Also, it was posted

twice in the images
file…so there’s nothing
to compare it to as far
as I can tell

42. Short vs Long Scale Contrast; kVp
2nd image of elbow

phantom
↑ to 70kVp

↓to 3mAs


43. Density Chart
Variables Effects Density Relationship
↑↓ ↓↑
Filtration Inverse
↑↓ ↓↑
Grid Inverse
↑↓ ↓↑
Tissue Thickness Inverse
↑↓ ↓↑
SID Inverse
↑↓ ↓↑
Collimation Inverse
Cathode: ↑
Anode Heel Effect *In theory the N/A unless film
Anode: ↓ anode heel effect screen technology
does cause a is involved
change in density
but this is not
evident in digital
imaging

44. Contrast Chart
Variable Effect Contrast Relationship
↑↓ ↓↑
kVp inverse
Ø Ø
mAs none
Ø Ø
SID none
↑↓ ↑↓
OID direct
↑↓ ↓↑
Filtration inverse
↑↓ ↑↓
Collimation direct
↑↓ ↓↑
Tissue Thickness inverse
↑
Contrast Media + direct
↑↓ ↑↓
Grid ratio direct
Ø Ø
Focal spot size none
↓ Always ↓ contrast
Film Processing *+/- developing
time and temp
beyond optimal

45. Detail Chart
Variable Effect Detail Relationship
↑↓ ↑↓
SID direct
↑↓ ↓↑
OID inverse
↑↓ ↓↑
Tissue Thickness inverse
↑↓ ↓↑
Focal Spot Size inverse
↑↓ ↓↑
Motion inverse