The document discusses key factors that contribute to radiographic image quality, including sharpness and visibility. Sharpness refers to the ability to clearly define edges and is influenced by factors like motion blur and material properties. Visibility refers to the distinguishability of distant objects and depends on density and contrast, which are also important quality metrics. Obtaining diagnostic images with both sharpness and visibility while minimizing radiation exposure requires consideration of numerous technical parameters like screen speed, mAs, kVp, and immobilization techniques. An optimal radiographic technique balances all relevant image quality attributes.

1. Radiographic Image
Obtaining the best diagnostic image
and good patient care are the two
ultimate goals of a technologist

2. Introduction
What is meant by an image that of
radiographic quality?

3. Sharp edges image
Unsharp edges image
Radiographs small bone with shot embedded in it

4. Motion blur (unsharpness)

5. Involuntary patient motion during radiography

6. Good Visibility
Poor Visibility
X-ray Sinuses

8. An image of radiographic quality is the one
that possesses :
 Sharpness &
 Visibility

9. Sharpness
 Ability to record individual lines that actually
form the image keen, distinct and thinedged.
 Sharpness is geometric properties of
radiograph.
 It is measurable factor of radiographic
quality.

10. Visibility
 Ability to discrete distant object
 It is photographic properties
 Visibility is quality factor of radiographic image.
 To determine the visibility, you should examine the
image for:
 Density
 Contrast

11. The quality of the manifest image is
assessed for
 Photographic
 Geometric properties
properties
 Sharpness
 Visibility
 Recorded detail
 Density
 distortion
 Contrast

12. Balance of sharpness and visibility
for radiographic quality

13. Radiographic Quality

14. Major Radiographic Properties




Recorded detail
Distortion
Density
contrast

15. Major Considerations
 (1) Recorded detail:
The actual formation of the
structural lines of the image as recorded on
the film.
 (2) Distortion:
The mispresntation of actual size or
shape of structures as recorded on the film,

16. Major Considerations
 (3)Density:
The completeness of the recording of image
on the film, indicating that sufficient quantities of
radiation passed through the body and reached
the film.
 (4)Contrast:
The ability to distinguish each recorded
structure apart from adjacent structures, indicating
that proper penetration of the part was achieved.

17. Visual Acuity of Human Eye
 The human eye enables the viewer to
discriminate up to 5 lie pairs within the
space of a millimeter. (a line pairs means a
line and space.)
 Level of unsharpness
 Visibility = 5 line pairs/mm
 >0.2 mm line pair width = intolerable level

19. Factors Influence The Sharpness
 Motion
 Material
} Measurable
 Geometry

20. Motion Unsharpness
 Voluntary
referred to as motion that
under conscious control of the will.
 Involuntary
motion attributed to the
physiological action of the of the body

21. Factors in Control of Motion
 Explanation of the procedure to the patient.
 Immobilization of the part.
Whole body immobilizers
Selected part immobilization
 Reduction of exposure time.

22. Immobilization aids

23. Immobilization of the part to avoid motional blurring.

24. Reduction of Exposure Time
 1- Milliamperage/Time Relationship
If the original techniqye required 100 mAs:
100 mA x 1sec =100 mAs
Change to :
400 mA x 0.25 sec = 100 mAs

25. Reduction of Exposure Time
2- Intensifying Screen Speeds:
 The radiographic density can be maintained with
an increase in the in the speed of intensifying
screens and an appropriate reduction in the
overall mAs . For example:
A demonstrates quantum mottle B demonstrates recorded details .
 If the original technique required 100 mAs:



400 mAs x 0.25 sec =100 mAs
Change to:
400 mAs x 0.125 sec = 50mAs with high speed screen.

26. Material Unsharpness
Three factors influence material
unsharpness:
 Film
 Intensifying screen.
 Film-screen contact

27. The three major factors influencing material unsharpness

28. Radiographic Film
Non screen Film:
 Has thicker emulsion.
 Two to six times faster compared with
screen-type film used with direct exposure.
 Not recommended for use with intensifying
screen.

29. Parallax

30. Radiographic Film
Screen -Type Film
 Has thinner emulsion.
 Slow in speed when used with direct
exposure.
 There is a significant increase in speed
when used with intensifying screen.

31. Comparison of typical exposure factors in an
AP projection of the knee(12:1moving grid)
– Type of radiography
exposure factors
– --------------------------------------------------------------– Ultrahigh speed screens
20mAs(100mAx0.2 sec at 60kvp)
– High speed screens
30mAs(100mAx0.3 sec at 60kvp)
– Par speed screens
60mAs(100mAx0.6 sec at 60kvp)
– Slow speed screen
120mAs(100mAx1.2 sec at 60kvp)
– Direct exposure
4800mAs(100mAx12 sec at 60kvp)

32. Quantum Mottle
 Radiographic noise produced by the
random interaction of x-rays with an
intensifying screen. This effect is more
noticeable when very high rare-earth
systems are used at high kvp.

33. Quantum Mottle (image noise)
 Occurs more often when fast screens and high
kvp techniques are used.
 Screen speed increased because of:
 1- High absorb percentage of x-ray this is called
detective quantum efficiency (DQE).
 2- The amount of light emitted for each x-ray
absorbed is also high. This is called conversion
efficiency (CE)

34. Quantum increases with higher CE
but not with higher DQE.

35. (A) demonstrates
quantum mottle
(B)
demonstrates
recorded details

36. Diffusion of light decrease image
sharpness

37. Advantages Using Nonscreen Film
 Improved Recorded details, Sharpness
Resolution.
 Production of longer scale contrast.
 Increase exposure latitude.
 Lack of artifacts associated with dirty
screen.
However ,with increased of radiation dose.

38. Comparison screen speed to image
details

39. Poor film screen contact

41. Poor film-screen contact

42. Good film-screen contact

43. DENSITY
 CONTROLLING FACTORS?
 INFLUENCING FACTORS?

44. CONTRAST
 Subject Contrast
 Film (IR) Contrast

45. CONTRAST
 CONTROLLING FACTORS?
 INFLUENCING FACTORS?

46. FACTORS THAT CONTROL AND
INFLUENCE VISIBLE RECORDED DETAIL
 What are they???
 Modifying patient exposure
– Pediatrics
– Projections/positions
– Casts/splints
– Body habitus
– Pathology –additive and destructive
– Soft tissue

47. Density factors
- Subject (tissue thickness and density)
- Technique (mA; s; kV; distance)
- Receptor quantum efficiency
- Image processing

48. Improved Quantum Efficiency
100
80
60
40
20
0
1919
1925
1941
1955
1981
% Relative Dose
1991
1999

49. Contrast Resolution vs. Dose
( cm bone, 40 kV)
40 KeV X-Rays
10
visible with
contrast
enhancement
10
10
`
not detectable
10
-2
-4
-6
10
-0
-2
10
visible without
contrast
enhancement
+2
10
10
-8
10
+4
-10
2
αX , C/kg - mm
X, mR - mm2
10 +6
S = 0.025
10
-4
0.0001
0.001
0.01
0.1
1
Signal Contrast Ratio, S
Derived from: Motz JW, Danos M. Image information content
and patient exposure. Med Phys 1978; 5: 8-22.

50. Contrast sources
Subject
Signal
Exposure energy
Receptor
Processing

52. Radiopacity and radiolucency are relative
terms. The central gray squares are all of
the same density.

53. The left triangle seems lighter than the right one.
This is only an illusion - they are equal in density.

54. Kanisza triangle: optical illusions can occur
when interpreting black and white images.