2. Components of Image Quality & Radiographic Artifacts Radiologic Technology A Spring 2010 Final Final

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

4. Review Chapter 7 Primary radiation exits the tube Primary radiation exits the tube Interacts with various densities in the body Interacts with various densities in the body Photons may be absorbed Photons may be absorbed Scattered Scattered Passed through without any interference to the cassette or image receptor (IR) Passed through without any interference to the cassette or image receptor (IR)

6. How well we can see something on the image

7. Image detail is affected by:

8. Photographic Properties 12

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

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

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

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

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

14. Factors Affecting Density Primary control factor: Primary control factor: Influencing factors: Influencing factors:

15. Primary Controlling Factor of Density 1. mAs 2. mA = AMOUNT of electrons sent across the tube combined with TIME (S) = mAs 3. mAs controls DENSITY on radiograph primary function of mAs is DENSITY

16. 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. 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 From 10 mA to 1000 mA = 100 x more mA controls how many electrons are coming at the target mA controls how many electrons are coming at the target mAs is a combination of how many and for how long (seconds) mAs is a combination of how many and for how long (seconds)

17. 10 mA1000 mA

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

20. Influencing Factor on Density:

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

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

23. + 15% kvp - 15% kvp

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

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

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

27. Why you see what you see… The films or images have different levels of density – different shades of gray 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. 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 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. The images are lighter in dense areas (like bones) that absorb more of the X-rays.

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

29. Patient Body Size and Pathology

30. 3 Different Body Habitus Hypersthenic Sthenic Hyposthenic Thank you to the 3 men in my life ! DCharman Dr. Charman, Eric Guzman, Adam Guzman

36. Density and Images

37. Goal: Producing optimal radiographs DENSITY Too dark Too light

39. Controlling Factor of Contrast

40. Kilovolts to anode side – kVp Kilovolts to anode side – kVp Kilovolts controls how fast the electrons are sent across the tube Kilovolts controls how fast the electrons are sent across the tube _______ – controls CONTRAST on images _______ – controls CONTRAST on images

41. Producing optimal radiographs Contrast Scale Long scale short scale

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

46. Short Scale vs. Long Scale

48. Beam Restriction and Grids

49. Scatter –Creates fog –Lowers contrast (more grays) Increases as: Increases as:

50. Effects of collimation (beam restriction) on scatter

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

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

53. GRID NO GRID CONTROLS CONTRAST

54. Basic Grid Construction 1. Radiopaque lead strips 2. Separated by radiolucent interspace material - Typically aluminum 3. Allow primary radiation to reach the image receptor (IR) 4. Absorb most scattered radiation 5. Primary disadvantage of grid use 1.Grid lines on film

55. GRIDS

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

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

59. With Grid No Grid

61. GEOMETRIC Properties Recorded Detail Recorded Detail DISTORTION DISTORTION –_____________ Magnification Magnification –_____________ Elongation Elongation Foreshortening Foreshortening

62. RECORDED DETAIL

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

64. Recorded Detail The degree of sharpness in an object’s borders and structural details. The degree of sharpness in an object’s borders and structural details. Other names: Other names:1.2.3.4.

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

67. Factors that affect Recorded Detail 1. Geometric unsharpness 2. OID SID SIZE SHAPE 3. Motion unsharpness (blurring) 4. Intensifying Screens 5. Film Speed / Composition 6. Film – Screen contact 7. Kvp & Mas (density / visibility)

69. MOTION AKA Blurring

70. Motion Can be voluntary or _____________ Can be voluntary or _____________ Best controlled by short exposure times Best controlled by short exposure times Use of careful _______________ to the pt. Use of careful _______________ to the pt. Suspension of pt. respiration Suspension of pt. respiration _____________________ devices _____________________ devices

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

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

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

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

80. OID Object to Image Distance The closer the object to the film, the sharper the detail. The closer the object to the film, the sharper the detail. OID , penumbra , sharpness  OID , penumbra , sharpness  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. Structures located deep in the body, radiographer must know how to position to get the object closest to the film.

81. 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

83. Distortion Misrepresentation of the true size or shape of an object Misrepresentation of the true size or shape of an object –________________ –size distortion –________________ –shape distortion

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

86. http://www.coursewareobjects.com/ob jects/mroimaging_v1/mod04i/0416a.ht m http://www.coursewareobjects.com/ob jects/mroimaging_v1/mod04i/0416a.ht m

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

89. In terms of recorded detail and magnification the best image is produced with a ______ OID & _____ SID

90. Minimal magnification small OID Magnification - large OID

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

97. SHAPE DISTORTION Elongation and Foreshortening

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

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

102. Central Ray Angulation Body parts are not always 90 degrees from one another 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. 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. Body part rotation or obliquing the body can also help visualize superimposed anatomy.

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

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

112. ANODE

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

115. http://www.xray2000.co.uk/

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

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

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

123. Artifact

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

142. ?

143. ?

145. Pt clothing

149. PATHOLOGY NOT ARTIFACT

150. Name & cause of this?

160. Evaluating Images What do you think?

161. Does this show good detail? Does this show good detail? Is all of the anatomy present? Is all of the anatomy present? How is the density / contrast? How is the density / contrast?