1. Components of Image Quality & Radiographic Artifacts
Radiologic Technology A
SPRING 2012

2. X-ray Exposure Factors
Radiographic Density & Contrast
Components of Image Quality
Radiographic Artifacts

3. Review Primary radiation exits the tube
Interacts with various densities in the body
Photons may be absorbed
Scattered
Passed through without any interference to the cassette or image receptor (IR)

5. How well we can see something on the image

6. Image detail is affected by: Photographic properties and Geometric properties

7. Photographic Properties
Contrast
Density

8. X-ray Exposure Factors
TECHNIQUE SELECTION:
Radiographer selects the
Kilovoltage peak (kVp)
Milliamperage (mA) & time (s)
Milliamperage x time = mAs
(milliamperage multiplied by a set time measured in seconds)

9. Kilovoltage Peak kVp One kilovolt = 1000 volts
The amount of voltage selected for the x-ray tube.
Range 30 to 150 kVp
kVp controls contrast

10. Milliamperage One milliampere (mA) = one thousandth of an ampere.
The amount of current supplied to the x-ray tube
How many x-rays will be produced
Range 10 to 1200 mA

11. Time
In seconds
How long x-rays will be produced
0.001 to 6 seconds

12. Milliampere Seconds Technologists think in terms of mAs
Calculated by mA x seconds
Ex: 100mA X 0.2s = 20 mAs
How many x-rays will be produced and for how long.
Modern x-ray machines only allow control of
mAs controls density

13. Factors Affecting Density
Primary control factor mA
Time (seconds)
Influencing factors
kVp
Grids
Beam restriction
Body structures (size of pt, pathology
Processing
SID & OID
Film Screen combinations

14. Primary Controlling Factor of Density
mAs
mA = AMOUNT of electrons sent across the tube combined with TIME (S) = mAs
mAs controls DENSITY on radiograph
primary function of mAs is DENSITY

15. Imagine this…
If the mA station is changed from 200 to 400 mA, twice as many electrons will flow from the cathode to the anode.
From 10 mA to 1000 mA = 100 x more
mA controls how many electrons are coming at the target
mAs is a combination of how many and for how long (seconds)

16. 10 mA
1000 mA

18. Changing Mas – Changes Density + 25 % + 50 % mas

19. Influencing Factor on Density: kVp

20. 15% kVp = doubling of exposure to the film
 kVp more energy = more photons passing though tissue & striking the image
15% kVp = doubling of exposure to the film
 15% kVp = halving of exposure to the film
15% rule will also change the contrast of the image because kV is the primary method of changing image contrast.
Remember :
15% change ( ) KVP has the same effect as doubling or ½ the MAS on density
15% rule:
15% kVp = doubling of exposure to the film
 15% kVp = halving of exposure to the film
15% rule will also change the contrast of the image because kV is the primary method of changing image contrast.
Remember :
15% change ( ) KVP has the same effect as doubling or ½ the MAS on density

21. Change in kVp
kVp controls the energy level of the electrons and subsequently the energy of the x-ray photons.
A change from 72 kVp will produce
x-rays with a lower energy than at
82 kVp
Difference between a ball traveling 72 mph and 82 mph (how much energy did it take to throw the ball at the rates?)

22. + 15% kvp - 15% kvp This will also influence the density on the image
Increasing kVp = increase energy reaching the IR

23. Radiolucent vs. Radiopaque
Radiolucent materials allow x-ray photons to pass through easily (soft tissue).
Radiopaque materials are not easily penetrated by x-rays (bones)

24. Creating the Image Transmission Scatter Absorption no interaction
Responsible for dark areas
Scatter
(grays) – produces no diagnostic info
Absorption
(photoelectric effect)
Responsible for light areas

25. Images
DENSITY = THE AMOUNT OF BLACKENING “DARKNESS” ON THE RADIOGRAPH (mAs)
CONTRAST – THE DIFFERENCES BETWEEN THE BLACKS TO THE WHITES (kVp)

26. Why you see what you see…
The films or images have different levels of density – different shades of gray
X-rays show different features of the body in various shades of gray.
The gray is darkest in those areas that do not absorb X-rays well – and allow it to pass through
The images are lighter in dense areas (like bones) that absorb more of the X-rays.

27. Image Production
Primary Radiation – The beam of photons, B4 it interacts with the pt’s body.
Remnant Radiation – The resulting beam that is able to exit from the patient.
Scatter Radiation – Radiation that interacts with matter & only continues in a different direction – not useful for image production.
Attenuation – Primary radiation that is changed (partially absorbed) as it travels through the pt.
Primary Radiation – The beam of photons, B4 it interacts with the pt’s body.
Remnant Radiation – The resulting beam that is able to exit from the patient.
Scatter Radiation – Radiation that interacts with matter & only continues in a different direction – not useful for image production.
Attenuation – Primary radiation that is changed (partially absorbed) as it travels through the pt.

28. Patient Body Size and Pathology

29. 3 Different Body Habitus Hypersthenic Sthenic Hyposthenic
Dr. Charman, Eric Guzman, Adam Guzman
Thank you to the 3 men in my life !  DCharman

30. PATHOLOGY
Pleural
Effusion
Excessive fluid in lung
More dense than air

31. Pneumonia

32. Pneumothorax The right lung is almost completely collapsed;
vascular shadows can not be seen in this area (arrow).
Lung collapses
No tissue in space
Easy to penetrate with x-ray photons
Pneumothorax

33. Lung Cancer

34. LUNG CANCER

35. Density and Images

36. Goal: Producing optimal radiographs DENSITY
Could be caused by kVP or mAs.
Too dark Too light

38. Controlling Factor of Contrast

39. Controlling Factor of Contrast
Kilovolts to anode side – kVp
Kilovolts controls how fast the electrons are sent across the tube
kVp – controls CONTRAST on images

40. Producing optimal radiographs Contrast Scale
Long scale short scale

42. Scale of Contrast? Which one is “better” How does the kVp affect these images?

45. Beam Restriction and Grids

46. Scatter Creates fog Lowers contrast (more grays) Increases as
kV increases
Field size increases
Thickness of part increases

47. Effects of collimation (beam restriction) on scatter

48. Collimate to area of interest -reduces scatter and radiation dose to the patient

49. Grids
A device with lead strips that is placed between the patient and the cassette
Used on larger body parts to reduce the number of scattering photons from reaching the image

50. Basic Grid Construction
Radiopaque lead strips
Separated by radiolucent interspace material - Typically aluminum
Allow primary radiation to reach the image receptor (IR)
Absorb most scattered radiation
Primary disadvantage of grid use
Grid lines on film

51. GRIDS

52. Grid is placed between patient (behind table or upright bucky) & cassette

53. Grids absorb scatter – prevents it from reaching the image
STOPS
SCATTER

55. Contrast changes with the use of a grid
Less scatter radiation – shorter scale = “better contrast”
With Grid No Grid

56. GRIDS CAN LEAVE LINES ON THE IMAGE

57. GEOMETRIC Properties Recorded Detail DISTORTION Size distortion
Magnification
Shape distortion
Elongation
Foreshortening

58. RECORDED DETAIL

59. The degree of sharpness in an object’s borders and structural details.
RECORDED DETAIL
The degree of sharpness in an object’s borders and structural details.
How “clear” the object looks on the radiograph

60. Recorded Detail
The degree of sharpness in an object’s borders and structural details.
Other names:
-sharpness of detail
-definition
-resolution
-degree of noise

61. RESOLUTION TEST
TOOLS
LINE PAIRS/ MM
Depicts how well you can see the differences in structures
More lines=more detail

63. Factors that affect Recorded Detail
Geometric unsharpness
OID SID SIZE SHAPE
Motion unsharpness (blurring)
Intensifying Screens
Film Speed / Composition
Film – Screen contact
Kvp & Mas (density / visibility)

65. MOTION AKA Blurring

66. Motion Can be voluntary or involuntary
Best controlled by short exposure times
Use of careful instructions to the pt.
Suspension of pt. respiration
Immobilization devices

68. Decrease Motion Unsharpness
Instruct patient not to move or breath
Use Immobilization devices
Use Short exposure times
Lock equipment in place

69. Blurring of image due to patient movement during exposure.

71. Object Unsharpness
Main problem is trying to image a 3-D object on a 2-D film.
Human body is not straight edges and sharp angles.
We must compensate for object unsharpness with factors we can control: focal spot size, SID & OID

72. SID Source to Image Distance
The greater the source X-ray tube) to image (cassette) distance, the greater the image sharpness.
Standard distance = 40 in. most exams
Exception = Chest radiography 72 in.

73. The SID will influence magnification
The SID will influence magnification. The farther away – the less magnified
↑SID ↓ MAGNIFICATION
The position of the tube (SID) to IR Will influence how the structures appear on the image The farther away – the less magnified ↑SID ↓ MAGNIFICATION

74. SID
Shine a flashlight on a 3-D object, shadow borders will appear “fuzzy”
-On a radiograph called Penumbra
Penumbra (fuzziness) obscures true border – umbra
Farther the flashlight from object = sharper borders. Same with radiography.

76. OID Object to Image Distance
The closer the object to the film, the sharper the detail.
OID , penumbra , sharpness 
OID , penumbra , sharpness 
Structures located deep in the body, radiographer must know how to position to get the object closest to the film.
The closer the object to the film, the sharper the detail.
OID , penumbra , sharpness 
OID , penumbra , sharpness 
Structures located deep in the body, radiographer must know how to position to get the object closest to the film.
*See page 74 in your book

77. The position of the structure in the body will influence how magnified it will be seen on the image
The farther away – the more magnified

79. Distortion Misrepresentation of the true size or shape of an object
MAGNIFICATION
size distortion
TRUE DISTORTION
shape distortion

80. MAGNIFICATION TUBE CLOSE TO THE PART (SID)
PART FAR FROM THE CASSETTE (OID)

81. Demonstrates increased OID which increases magnification

82. http://www. coursewareobjects. com/objects/mroimaging_v1/mod04i/0416a

83. Size Distortion & OID
If source is kept constant, OID will affect magnification
As OID , magnification 
The farther the object is from the film, the more magnification

84. Which side is more magnified?

85. In terms of recorded detail and magnification the best image is produced with a
small OID & large SID

86. Minimal magnification small OID
Magnification - large OID

87. Size Distortion & SID Major influences: SID & OID
As SID , magnification 
Standardized SID’s allow radiologist to assume certain amt. of magnification factors are present
Must note deviations from standard SID
Major influences: SID & OID
As SID , magnification 
Standardized SID’s allow radiologist to assume certain amt. of magnification factors are present
Must note deviations from standard SID

91. 40” SID VS 72” SID

93. SHAPE DISTORTION Elongation and Foreshortening

94. Shape Distortion Misrepresentation of the shape of an object
Controlled by alignment of the beam, part (object), & image receptor
Influences: Central ray angulation & body part rotation

95. A = good B & C = shape distortion (elongation of part)

96. D & E = shape distortion (foreshortening of part)

97. Image Distortion
When the part to be imaged – does not lay parallel with the IR (cassette)
If the Central Ray is not perpendicular to the part
CR should be at right angle with the cassette

98. Central Ray Angulation
Body parts are not always 90 degrees from one another
Central ray angulation is used to demonstrate certain details that can be hidden by superimposed body parts.
Body part rotation or obliquing the body can also help visualize superimposed anatomy.

99. Central Ray Radiation beam diverges from the tube in a pyramid shape.
Photons in the center travel along a straight line – central ray
Photons along the beam’s periphery travel at an angle
When central ray in angled, image shape is distorted.

103. Elongation Foreshortened Normal

105. Distortion (x-ray beam not centered over object & film)
Distortion (object & film not parallel)

106. Distortion of multiple objects in same image (right) due to x-ray beam not being centered over objects.

107. Focal Spot Size Smaller x-ray beam width will produce a sharper image.
Fine detail = small focal spot (i.e. small bones)
General radiography uses large focal spot
Beam from penlight size flashlight vs. flood light beam

108. ANODE
ANODE

109. THE SMALLER THE BEAM TOWARDS THE PATIENT - THE BETTER THE DETAIL OF THE IMAGE PRODUCED

110. FOCAL SPOT ANGLE
SMALLER ANGLE – SMALLER BEAM AT PATIENT

111. ARTIFACTS: AN UNWANTED DENSITY ON THE FILM

112. Artifacts - Types
Processing Artifacts
Exposure Artifacts
Handling & Storage Artifacts

113. Processing Artifacts Emulsion pickoff Chemical fog Guide-shoe marks
Water marks
Chemical spots
Guide-shoe & roller scratches

114. Developer Spots

115. Water spot

116. Discolored film due to hypo (fixer) retention.
Chemicals not washed off – over time will turn film brown

117. Scratch marks from rollers in automatic processor.

118. Exposure Artifacts Motion Improper patient position
Wrong screen-film match
Poor film/screen contact
Double exposure
Warped cassette
Improper grid position

119. Artifact

121. Blurred image due to patient motion

122. PATIENT ARTIFACT - JEWERLY

123. Handling & Storage Artifacts
Light fog
Radiation fog
Static
Kink marks
Scratches
Dirty cassettes

124. Crimping /cresent mark

125. 2 exposures made on top of each other –
Double Exposure
2 exposures made on top of each other –
from poor handling of cassettes

127. Static electricity

128. Dirt on screen mimicking a foreign object.

129. Scratch marks from improper handling.

130. Light fog

131. Kink mark or nail pressure mark

132. cast

133. POOR SCREEN CONTACT

134. Patient motion

135. motion

136. Double exposure Child

137. Poor screen contact

138. Double exposure

139. ?

140. ?
Is it motion or double exposure

142. Pt clothing

143. Hip replacement

144. 2 chest tubes in the patient

145. Patient swallowed batteries
What size are they?

147. PATHOLOGY NOT ARTIFACT

148. Name & cause of this?

149. scratches

150. Digital image
Mis-
Registration
error

151. Roller marks from film stuck – then pulled from processor

152. Hardware
In cervical
spine

153. Dust in imaging plate can cause white marks on image
Both in film/screen and computed radiography

154. E E G MONITOR

155. What do you
See?
2 exposures

158. Evaluating Images
What do you think?

159. See anything wrong with this image?

160. Contrast? What influences this? (kVp in f/s)

161. Collimation – reducing the size of beam helps to improve the image, and reduce the dose to the patient

162. ?