Radiographic image4

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

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

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

4. Motion blur (unsharpness)

5. Involuntary patient motion during radiography

6. Good VisibilityGood Visibility Poor VisibilityPoor Visibility
X-ray Sinuses

8. An image of An image of radiographicradiographic qualityquality is the one is the one
that possesses :that possesses :
Sharpness &Sharpness &
Visibility Visibility

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

10. VisibilityVisibility
Ability to discrete distant objectAbility to discrete distant object
It is photographic propertiesIt is photographic properties
VisibilityVisibility is quality factor of radiographic image. is quality factor of radiographic image.
To determine the visibility, you should examine the To determine the visibility, you should examine the
image for:image for:
DensityDensity
CCoonnttrraasstt

11. The quality of the manifest image is The quality of the manifest image is
assessed forassessed for
Photographic Photographic
propertiesproperties
VisibilityVisibility
DensityDensity
ContrastContrast
Geometric propertiesGeometric properties
SharpnessSharpness
Recorded detailRecorded detail
distortiondistortion

12. Balance of sharpness and visibility Balance of sharpness and visibility
for radiographic qualityfor radiographic quality

13. Radiographic QualityRadiographic Quality

14. Major Radiographic PropertiesMajor Radiographic Properties
Recorded detailRecorded detail
DistortionDistortion
DensityDensity
contrastcontrast

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

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

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

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

20. Motion UnsharpnessMotion Unsharpness
VoluntaryVoluntary referred to as motion that referred to as motion that
under conscious control of the will.under conscious control of the will.
InvoluntaryInvoluntary motion attributed to the motion attributed to the
physiological action of the of the bodyphysiological action of the of the body

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

22. Immobilization aidsImmobilization aids

23. Immobilization of the part to avoid motional blurring.Immobilization of the part to avoid motional blurring.

24. Reduction of Exposure TimeReduction of Exposure Time
1- Milliamperage/Time Relationship1- Milliamperage/Time Relationship
If the original techniqye required 100 mAs:If the original techniqye required 100 mAs:
100 mA x 1sec =100 mAs100 mA x 1sec =100 mAs
Change to :Change to :
400 mA x 0.25 sec = 100 mAs400 mA x 0.25 sec = 100 mAs

25. Reduction of Exposure TimeReduction of Exposure Time
2- Intensifying Screen Speeds:2- Intensifying Screen Speeds:
The radiographic density can be maintained with The radiographic density can be maintained with
an increase in the in the speed of intensifying an increase in the in the speed of intensifying
screens and an appropriate reduction in the screens and an appropriate reduction in the
overall mAs . For example:overall mAs . For example:
If the original technique required 100 mAs:If the original technique required 100 mAs:
400 mAs x 0.25 sec =100 mAs400 mAs x 0.25 sec =100 mAs
Change to:Change to:
400 mAs x 0.125 sec = 50mAs with high speed screen.400 mAs x 0.125 sec = 50mAs with high speed screen.
A demonstrates quantum mottle B demonstrates recorded details .A demonstrates quantum mottle B demonstrates recorded details .

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

27. The three major factors influencing material unsharpnessThe three major factors influencing material unsharpness

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

29. Parallax Parallax

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

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

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

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

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

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

36. Diffusion of light decrease image Diffusion of light decrease image
sharpnesssharpness

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

38. Comparison screen speed to image Comparison screen speed to image
detailsdetails

39. Poor film screen contactPoor film screen contact

41. Poor film-screen contactPoor film-screen contact

42. Good film-screen contactGood film-screen contact

43. DENSITYDENSITY
CONTROLLING FACTORS?CONTROLLING FACTORS?
INFLUENCING FACTORS?INFLUENCING FACTORS?

44. CONTRASTCONTRAST
Subject ContrastSubject Contrast Film (IR) ContrastFilm (IR) Contrast

45. CONTRASTCONTRAST
CONTROLLING FACTORS?CONTROLLING FACTORS?
INFLUENCING FACTORS?INFLUENCING FACTORS?

46. FACTORS THAT CONTROL AND FACTORS THAT CONTROL AND
INFLUENCE VISIBLE RECORDED DETAILINFLUENCE VISIBLE RECORDED DETAIL
What are they???What are they???
Modifying patient exposureModifying patient exposure
–PediatricsPediatrics
–Projections/positionsProjections/positions
–Casts/splintsCasts/splints
–Body habitusBody habitus
–Pathology –additive and destructivePathology –additive and destructive
–Soft tissueSoft tissue

47. - - Subject (tissue thickness and density)Subject (tissue thickness and density)

- Technique (mA; s; kV; distance)- Technique (mA; s; kV; distance)

- Receptor quantum efficiency- Receptor quantum efficiency

- Image processing- Image processing
Density factorsDensity factors

48. Improved Quantum Efficiency
% Relative Dose
191919251941 1955198119911999
0
20
40
60
80
100

49. Contrast Resolution vs. DoseContrast Resolution vs. Dose
( cm bone, 40 kV)( cm bone, 40 kV)
Signal Contrast Ratio, S
X
,

m
R

-

m
m
2
`
0.0001 0.001 0.01 0.1 1
10
-4
10
-2
10
-0
10
+2
10
+4
10
+6
not detectable
visible without
contrast
enhancement
visible with
contrast
enhancement
40 KeV X-Rays
10
-10
10
-8
10
-6
10
-4
10
-2
a
X
,

C
/
k
g

-

m
m
2
S = 0.025
Derived from: Motz JW, Danos M. Image information content
and patient exposure. Med Phys 1978; 5: 8-22.

50. Subject Subject
Signal Signal
Exposure energy Exposure energy
Receptor Receptor
ProcessingProcessing
Contrast sourcesContrast sources

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.