12. SPECT/CT Technology

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  • BGO - Bismuth Gremanate
    LSO - Lutetium Oxyorthosilicate
    GSO - Gadolinium Oxyorthosilicate
  • It is important to explain why there is a proportionality between the photon energy absorbed in the detector and the pulse height
  • Explain the origin of the scattered photons (detector and sample) and the completely absorbed photons.
  • The explanation to the better energy resolution in a semiconductor detector is that the energy needed to create a ion-hole pair is much less than the energy to produce a light photon in the scintillation detector. The statistical fluctuation and hence the width of the full energy peak will be much less.
  • The ECG gated acquisition is a type of dynamic acquisition. The RR-interval is divided into a certain number of frames (16 to 32) where each frame then represents a certain phase (t) of the heart cycle. Each time the R-peak in the ECG is detected the collection of data starts in frame 1 during time t, then in frame 2 during time t and so on. The total acquisition time is generally about 10 min so the whole study represents several hundred heart cycles.
  • There are methods to change the radionuclide distribution. In this case (examination of the myocaedium using Tc99 sestamibi) the uptake in the liver and emptying of the gallbladder can be stimulated by giving the patient a fatty meal.
  • This image should be used to explain the principle of filtered back projection. Note that the image contains an animation.
  • The image can be used to illustrate that gammacamera tomography is imaging of a volume where slices can be displayed in any plane.
  • This is an example of a surface rendered image combined with the information in the coronal slices. The patient has an iscemic heart disease.
  • This is an animated image and shows the information in three tomographic planes as well as a surface rendered image to illustrate wall motion.
  • The image to the right is aquired after cleaning of the collimator
  • The lower image is the absolute difference between the upper two images. It clearly shows the ring artifacts.
  • The images in the lower row are acquired using a collimator with 50% lower sensitivity in an 1cm3 area in the center of the field of view. The images in the upper row are from the same patient acquired with a good collimator. It is important to point out the risk of false positive results if the camera is not working perfectly,
  • This image tries to illustrate the problem that could come up if the positioning of an absorption event is dependent on the energy of the photon. If the examination requires a subtraction of two images the result will depend on the positioning rather than the patient, The images are from a parathyroid scan. The left images show the result of subtraction of the upper two images and how the result will be affected by the offset in positioning. The image to the right shows the ”truth”.
  • These are transversal slices of a myocardial tomography. They show the possible effects of an offset in center of rotation. The matrix size is 64x64 and the pixel size is 5 mm. Equivalent to an offset in center of rotation is patient movement during acquisition.
  • Remember that compton scattering is the dominating process in the attenuation of photons in soft tissue.
  • In the case of a big patient some of the full energy photons that should have reached the gamma camera will be scattered in the patient. The relation scattered/full energy photons will increase with the volume of the patient.
  • The image can be used to discuss the optimum relation between sensitivity and image quality.
  • This is an illustration to the triple energy window scatter correction. Two narrow windows are used, one on each side of the full energy peak. This information is used to determine the amount of scatter in the full energy window, simply by interpolation. The left image is a planar thallium scan and the middle image is the calculated scatter image which is subtracted from the left image, The result is shown in the right image. Improvement?
  • This figure tries to explain the origin of the detected photons. It is purely theoretical. Assume an object 20x20x20 cm3 filled with Tc99m. The diagram shows that 12% of the registered photons come from the first cm of the object Only 4% of the registered photons comes from 10cm and 1% from 20 cm
  • This is again the same theoretical phantom and the expected contrast in an image of a 2cm thick object containing no activity.
  • This is an example of how to measure the spatial resolution from the line spread function. It also gives an example of the MTF.
  • The pixel size is used in several application programmes for calculation of distance, surface and volume.
  • These are some examples of the sealed sources used in a nuclear medicine department
  • Note that there different types of generators. This illustrates a dry type with a separate container of saline solution that is changed every time a new elution will be made. In the wet type of generator there is a built in container with enough volume of saline solution for all elutions
  • Example of a transport container for a Tc generator
  • This image shows that extra shielding of the generator should be used.as well as shielding of the elution vial
  • This is a closer look at the top of the generator with the needles where the elution vial and the saline solution vial are placed
  • The shielded elution vial
  • The image can be used for a short explanation of a radiopharmaceutical. The same radioactive substance can be used in labeling of different compunds resulting in radiopharmaceuticals with different properties
  • This is an introduction to the ICRP concept of categorization of hazard which should be used to define some basic building requirements.
  • This is an example of a calculation of the weighted activity. In this case the room for administration of an iodine therapy is a high hazard room
  • These are examples of categorization of hazard for different rooms in a typical nuclear medicine department handling quite large amounts of Tc99m
  • Rooms where work with unsealed sources are taken place should be under negative pressure to minimize the risk of airborne radionuclides to be spread, The sterile environment that might be necessary in preparation of radiopharmaceuticals is achieved in a laminar air flow bench.
  • If there are regulations about air pressure gradients they should be continously monitored and an alarm system introduced
  • This illustartion is from a Nuclear Medicine department in India. Does it follow the general rule to separate high activity areas from low activity areas and to separate working areas from patient areas?
  • 12. SPECT/CT Technology

    1. 1. International Atomic Energy Agency L 12 SPECT/CT TECHNOLOGY & FACILITY DESIGN
    2. 2. Radiation Protection in PET/CT 2 Answer True or False • The most common isotope used in SPECT/CT scans is 18 F • SPECT scanners work by detecting coincidences of two 511 keV gamma rays • The facility design concepts are almost identical to those used in designing PET/CT facilities
    3. 3. Radiation Protection in PET/CT 3 Objective To become familiar with basic SPECT/CT technology, and review considerations in establishing a new SPECT/CT facility
    4. 4. Radiation Protection in PET/CT 4 • SPECT cameras • Image Quality & CImage Quality & Camera QA • SPECT/CT scanners • Design of SPECT/CT facilities Content
    5. 5. International Atomic Energy Agency 12.112.1 SPECT cameras
    6. 6. Radiation Protection in PET/CT 6 Scintillators • Na(Tl) I works well at 140 keV, and is the most common scintillator used in SPECT cameras Density (g/cc) Z Decay time (ns) Light yield (% NaI) Atten. length (mm) Na(Tl)I 3.67 51 230 100 30 BGO 7.13 75 300 15 11 LSO 7.4 66 47 75 12 GSO 6.7 59 43 22 15
    7. 7. Radiation Protection in PET/CT 7 Detector Photocathode cathodd Dynodes Anode Amplifier PHA Scaler Scintillation detector
    8. 8. Radiation Protection in PET/CT 8 Pulse height analyzer UL LL Time Pulse height (V) The pulse height analyzer allows only pulses of a certain height (energy) to be counted. counted not counted
    9. 9. Radiation Protection in PET/CT 9 Pulse-height distribution NaI(Tl)
    10. 10. Radiation Protection in PET/CT 10 Semi-conductor detector as spectrometer • Solid Germanium or Ge(Li) detectors • Principle: electron - hole pairs (analogous to ion-pairs in gas-filled detectors) • Excellent energy resolution
    11. 11. Radiation Protection in PET/CT 11 Knoll Comparison of spectrum from a Na(I) scintillation detector and a Ge(Li) semi-conductor detector
    12. 12. Radiation Protection in PET/CT 12 Gamma camera Used to measure the spatial and temporal distribution of a radiopharmaceutical
    13. 13. Radiation Protection in PET/CT 13 Gamma camera (principle of operation) PM-tubes Detector Collimator Position X Position Y Energy Z
    14. 14. Radiation Protection in PET/CT 14 Counter Clock PulsesEnergy windowr Time PHA ADC Computer Patient z x y GAMMA CAMERA
    15. 15. Radiation Protection in PET/CT 15 PM-tubes
    16. 16. Radiation Protection in PET/CT 16 Gamma camera collimators
    17. 17. Radiation Protection in PET/CT 17 Static Dynamic ECG-gated Wholebody scanning Tomography ECG-gated tomography Wholebody tomography Gamma camera Data acquisition
    18. 18. Radiation Protection in PET/CT 18 R Interval n Image n ECG-gated acquisition
    19. 19. Radiation Protection in PET/CT 19 Scintigraphy seeks to determine the distribution of a radiopharmaceutical
    20. 20. Radiation Protection in PET/CT 20 SPECT cameras are used to determine the three-dimensional distribution of the radiotracer
    21. 21. Radiation Protection in PET/CT 21 Tomographic acquisition
    22. 22. Radiation Protection in PET/CT 22 y z x x-position Count rate z y Tomographic reconstruction
    23. 23. Radiation Protection in PET/CT 23 Tomographic planes
    24. 24. Radiation Protection in PET/CT 24 Myocardial scintigraphy
    25. 25. Radiation Protection in PET/CT 25 ECG GATED TOMOGRAPHY
    26. 26. International Atomic Energy Agency 12.2 Image Quality & C12.2 Image Quality & Camera QA
    27. 27. Radiation Protection in PET/CT 27 •Distribution of radiopharmaceutical •Collimator selection and sensitivity •Spatial resolution •Energy resolution •Uniformity •Count rate performance •Spatial positioning at different energies •Center of rotation •Scattered radiation •Attenuation •Noise •Distribution of radiopharmaceutical •Collimator selection and sensitivity •Spatial resolution •Energy resolution •Uniformity •Count rate performance •Spatial positioning at different energies •Center of rotation •Scattered radiation •Attenuation •Noise Factors affecting image formation
    28. 28. Radiation Protection in PET/CT 28 Sum of intrinsic resolution and the collimator resolution Intrinsic resolution depends on the positioning of the scintillation events (detector thickness, number of PM-tubes, photon energy) Collimator resolution depends on the collimator geometry (size, shape and length of the holes) SPATIAL RESOLUTION
    29. 29. Radiation Protection in PET/CT 29 Object Image Intensity SPATIAL RESOLUTION
    30. 30. Radiation Protection in PET/CT 30 Resolution - distance 0 5 10 15 20 25 30 0 2 4 6 8 10 12 14 16 Distance (cm) FWHM(mm) High sensitivity High resolution FWHM
    31. 31. Radiation Protection in PET/CT 31 Optimal Large distance SPATIAL RESOLUTION - DISTANCE
    32. 32. Radiation Protection in PET/CT 32 Linearity
    33. 33. Radiation Protection in PET/CT 33 NON UNIFORMITY
    34. 34. Radiation Protection in PET/CT 34 NON UNIFORMITY Cracked crystal
    35. 35. Radiation Protection in PET/CT 35 NON-UNIFORMITY (Contamination of collimator)
    36. 36. Radiation Protection in PET/CT 36 NON UNIFORMITY RING ARTIFACTS Good uniformity Bad uniformity Difference
    37. 37. Radiation Protection in PET/CT 37 NON-UNIFORMITY Defect collimator
    38. 38. Radiation Protection in PET/CT 38 COUNT RATE PERFORMANCE (IAEA QC Atlas)
    39. 39. Radiation Protection in PET/CT 39 Spatial positioning at different energies Intrinsic spatial resolution with Ga-67 Point source (count rate < 20k cps); quadrant bar pattern; 3M counts; preset energy window widths; summed image from energy windows set over the 93 keV, 183 keV and 296 keV photopeaks. (IAEA QC Atlas)
    40. 40. Radiation Protection in PET/CT 40 Spatial positioning at different energies
    41. 41. Radiation Protection in PET/CT 41 Center of Rotation
    42. 42. Radiation Protection in PET/CT 42 Tilted detector
    43. 43. Radiation Protection in PET/CT 43 Scattered radiation photon electron Scattered photon
    44. 44. Radiation Protection in PET/CT 44 The amount of scattered photons registered Patient size Energy resolution of the gammacamera Window setting
    45. 45. Radiation Protection in PET/CT 45 PATIENT SIZE
    46. 46. Radiation Protection in PET/CT 46 Pulse height distribution Energy Counts 0 20 40 60 80 100 120 140 20 60 100 120 140 160 Tc99m Full energy peak Scattered photonsThe width of the full energy peak (FWHM) is determined by the energy resolution of the gamma camera. There will be an overlap between the scattered photon distribution and the full energy peak, meaning that some scattered photons will be registered. FWHM Overlapping area
    47. 47. Radiation Protection in PET/CT 47 Window width 20% 10%40% Increased window width will result in an increased number of registered scattered photons and hence a decrease in contrast
    48. 48. Radiation Protection in PET/CT 48 SCATTER CORRECTION
    49. 49. Radiation Protection in PET/CT 49 -20 -15 -10 -5 0 0 20 40 60 80 100 120 140 Register 1000 counts Origin of counts ATTENUATION I=I0 exp(-µx)
    50. 50. Radiation Protection in PET/CT 50 Contrast (2cm object) 23% 7% 2% ATTENUATION
    51. 51. Radiation Protection in PET/CT 51 ATTENUATION CORRECTION
    52. 52. Radiation Protection in PET/CT 52 ATTENUATION CORRECTION Transmission measurements • Sealed source • CT
    53. 53. Radiation Protection in PET/CT 53 ATTENUATION CORRECTION Ficaro et al Circulation 93:463-473, 1996
    54. 54. Radiation Protection in PET/CT 54 Count density NOISE
    55. 55. Radiation Protection in PET/CT 55 Gamma camera Operational considerations •Collimator selection •Collimator mounting •Distance collimator-patient •Uniformity •Energy window setting •Corrections (attenuation, scatter) •Background •Recording system •Type of examination
    56. 56. Radiation Protection in PET/CT 56 Acceptance Daily Weekly Yearly Uniformity P T T P Uniformity, tomography P P Spectrum display P T T P Energy resolution P P Sensitivity P T P Pixel size P T P Center of rotation P T P Linearity P P Resolution P P Count losses P P Multiple window pos P P Total performance phantom P P P: physicist, T:technician QC GAMMA CAMERA
    57. 57. Radiation Protection in PET/CT 57 IAEA-TECDOC-602 Quality control of Nuclear medicine instruments 1991 INTERNATIONAL ATOMIC ENERGY AGENCY IAEA May 1991 IAEA-TRS- 454 Quality Assurance for Radioactivity Measurement in Nuclear Medicine 2006 IAEA QA for SPECT systems (in press)
    58. 58. Radiation Protection in PET/CT 58 QC Gamma camera
    59. 59. Radiation Protection in PET/CT 59 Energy resolution
    60. 60. Radiation Protection in PET/CT 60 Linearity Flood source or point source (Tc-99m) Bar phantom or orthogonal-hole phantom 1. Subjective evaluation of the image. 2. Calculate absolute (AL) and differential (DL) linearity. AL: Maximum displacement from ideal grid (mm) DL: Standard deviation of displacements (mm)
    61. 61. Radiation Protection in PET/CT 61 Flood source (Tc-99m, Co-57) Point source (Tc-99m) Intrinsic uniformity: Point source at a large distance from the detector. Acquire an image of 10.000.000 counts With collimator: Flood source on the collimator. Acquire an image of 10.000.000 counts UNIFORMITY
    62. 62. Radiation Protection in PET/CT 62 Uniformity 1. Subjective evaluation of the image 2. Calculate Integral uniformity (IU) Differential uniformity (DU) IU=(Max-Min)/Max+Min)*100, where Max is the the maximum and Min is the minimum counts in a pixel DU=(Hi-Low)/(Hi+Low)*100, where Hi is the highest and Low is the lowest pixel value in a row of 5 pixels moving over the field of view Matrix size 64x64 or 128x128
    63. 63. Radiation Protection in PET/CT 63 UNIFORMITY/DIFFERENT RADIONUCLIDES D BOULFELFEL Dubai Hospital All 4 images acquired with: Matrix: 256 x 256, # counts: 30 Mcounts Tl 201 Ga 67 Tc 99m I 131
    64. 64. Radiation Protection in PET/CT 64 LINEARITY AND UNIFORMITY CORRECTIONS Dogan Bor, Ankara
    65. 65. Radiation Protection in PET/CT 65 OFF PEAK MEASUREMENTS Dogan Bor, Ankara
    66. 66. Radiation Protection in PET/CT 66 TOMOGRAPHIC UNIFORMITY Tomographic uniformity is the uniformity of the reconstruction of a slice through a uniform distribution of activity SPECT phantom with 200-400 MBq Tc99m aligned with the axis of rotation. Acquire 250k counts per angle. Reconstruct the data with a ramp filter
    67. 67. Radiation Protection in PET/CT 67 INCORRECT MEASUREMENT Two images of a flood source filled with a solution of Tc-99m, which had not been mixed properly
    68. 68. Radiation Protection in PET/CT 68 Spatial resolution Measured with: Flood source or point source plus a Bar phantom Subjective evaluation of the image
    69. 69. Radiation Protection in PET/CT 69 SPATIAL RESOLUTION Lead 200 mm 50 mm Screw clip Polyethylene tubing about 0.5 mm in internal diameter Plastic shims 500 mm Rigid plastic 30 mm 60 mm 5 mm Intrinsic resolution System resolution IAEA TECDOC 602
    70. 70. Radiation Protection in PET/CT 70 Tc-99m or other radionuclide in use Intrinsic: Collimated line source on the detector System: Line source at a certain distance Calculate FWHM of the line spread function FWHM: 7.9 mm SPATIAL RESOLUTION
    71. 71. Radiation Protection in PET/CT 71 TOMOGRAPHIC RESOLUTION Method 1: Measurement with the Jaszczak phantom, with and without scatter (phantom filled with water and with no liquid) Method 2: Measurement with a Point or line source free in air and Point or line source in a SPECT phantom with water
    72. 72. Radiation Protection in PET/CT 72 SensitivitySensitivity Expressed as counts/min/MBq andExpressed as counts/min/MBq and should be measured for each collimatorshould be measured for each collimator Important to observe with multi-headImportant to observe with multi-head systems that variations among heads dosystems that variations among heads do not exceed 3%not exceed 3%
    73. 73. Radiation Protection in PET/CT 73
    74. 74. Radiation Protection in PET/CT 74 Multiple Window Spatial Registration • Performed to verify that contrast is satisfactory for imaging radionuclides, which emit photons of more than one energy (e.g. Tl-201, Ga-67, In-111, etc.) as well as in dual radionuclides studies
    75. 75. Radiation Protection in PET/CT 75 Multiple Window Spatial Registration • Collimated Ga-67 sources are used at central point, four points on the X-axis and four points on the Y axis • Perform acquisitions for the 93, 184 and 300 keV energy windows • Displacement of count centroids from each peak is computed and maximum is retained as MWSR in mm
    76. 76. Radiation Protection in PET/CT 76 Count Rate Performance • Performed to ensure that the time to process an event is sufficient to maintain spatial resolution and uniformity in clinical images acquired at high-count rates
    77. 77. Radiation Protection in PET/CT 77 Count Rate Performance • Use of decaying source or calibrated copper sheets to compute the observed count rate for a 20% count loss and the maximum count rate without scatter
    78. 78. Radiation Protection in PET/CT 78 Pixel size
    79. 79. Radiation Protection in PET/CT 79 Center of rotation Point source of Tc-99m or Co-57 Make a tomographic acquisition In x-direction the position will describe a sinus- function. In y-direction a straight line. Calculate the offset from a fitted cosine and linear function at each angle. Cosine function Linear function
    80. 80. Radiation Protection in PET/CT 80 Total performance phantom. Emission or transmission. Compare result with reference image. Total performance
    81. 81. Radiation Protection in PET/CT 81 SOURCES FOR QC OF GAMMA CAMERAS •Point source •Collimated line source •Line source •Flood source Tc99m, Co57, Ga67 <1 mm
    82. 82. Radiation Protection in PET/CT 82 Phantoms for QC of gamma cameras •Bar phantom •Slit phantom •Orthogonal hole phantom •Total performance phantom
    83. 83. Radiation Protection in PET/CT 83 Phantoms for QC of gamma cameras
    84. 84. Radiation Protection in PET/CT 84 QUALITY CONTROL ANALOGUE IMAGES Quality control of film processing: base & fog, sensitivity, contrast
    85. 85. Radiation Protection in PET/CT 85 Efficient use of computers can increase the sensitivity and specificity of an examination. * software based on published and clinically tested methods * well documented algorithms * user manuals * training * software phantoms QUALITY ASSURANCE COMPUTER EVALUATION
    86. 86. Radiation Protection in PET/CT 86 •Identification of nuclides •Control of radionuclide purity Semi-conductor detector Applications in nuclear medicine
    87. 87. International Atomic Energy Agency 12.3. SPECT/CT12.3. SPECT/CT
    88. 88. Radiation Protection in PET/CT 88 TYPICAL SPECT/CT CONFIGURATION The most prevalent form of SPECT/CT scanner involves a dual- detector SPECT camera with a 1- slice or 4-slice CT unit mounted to the rotating gantry; 64-slice CT for SPECT/CT also available
    89. 89. Radiation Protection in PET/CT 89 SPECT/CT • Accurate registration • CT data used for attenuation correction Localization of abnormalities • Parathyroid lesions (especially for ectopic lesions) • Bone vs soft tissue infections • CTCA fused with myocardial perfusion for 64-slice CT scanners
    90. 90. Radiation Protection in PET/CT 90 The CT Scanner • Computed Tomography (CT) was introduced into clinical practice in 1972 and revolutionized X Ray imaging by providing high quality images which reproduced transverse cross sections of the body. • Tissues are therefore not superimposed on the image as they are in conventional projections • The technique offered in particular improved low contrast resolution for better visualization of soft tissue, but with relatively high absorbed radiation dose
    91. 91. Radiation Protection in PET/CT 91 The CT Scanner X ray emission in all directions X ray tube collimators
    92. 92. Radiation Protection in PET/CT 92 X Ray Tube Detector Array and Collimator A look inside a rotate/rotate CT
    93. 93. Radiation Protection in PET/CT 93 A Look Inside a Slip Ring CT X Ray Tube Detector Array Slip Ring Note: how most of the electronics is placed on the rotating gantry
    94. 94. Radiation Protection in PET/CT 94 What are we measuring in a CT scanner? • We are measuring the average linear attenuation coefficient µ between tube and detectors • The attenuation coefficient reflects how the x ray intensity is reduced by a material
    95. 95. Radiation Protection in PET/CT 95 Conversion of µ to CT number • Distribution of µ values initially measured ∀µ values are scaled to that of water to give the CT number
    96. 96. International Atomic Energy Agency 12.512.5 Design of SPECT/CT facilities
    97. 97. Radiation Protection in PET/CT 97 Radionuclide • Pure γ emitter  (−) e.g. ; Tc99m, In111, Ga67, I123 • Positron emitters (ß+ )  − e.g. : F-18 ∀γ, ß- emitters   e.g. : I131, Sm153 • Pure ß- emitters −  e.g. : Sr89, Y90, Er169 ∀α emitters −  e.g. : At211, Bi213 Diagnostics Therapy Nuclear medicine application according to type of radionuclide
    98. 98. Radiation Protection in PET/CT 98 Sealed sources in nuclear medicine Sealed sources used for calibration and quality control of equipment (Na-22, Mn-54, Co57, Co-60, Cs137, Cd-109, I-129, Ba-133, Am-241). Point sources and anatomical markers (Co- 57, Au-195). The activities are in the range 1 kBq-1GBq.
    99. 99. Radiation Protection in PET/CT 99 99 Mo-99m Tc GENERATOR 99 Mo 87.6% 99m Tc γ 140 keV T½ = 6.02 h 99 Tc ß- 292 keV T½ = 2*105 y 99 Ru stable 12.4% ß- 442 keV γ 739 keV T½ = 2.75 d
    100. 100. Radiation Protection in PET/CT 100 Mo-99 Tc-99m Tc-99 66 h 6h NaCl AlO2 Mo-99 +Tc-99m Tc-99m Technetium generator
    101. 101. Radiation Protection in PET/CT 101 Technetium generator
    102. 102. Radiation Protection in PET/CT 102 Technetium generator
    103. 103. Radiation Protection in PET/CT 103 Technetium generator
    104. 104. Radiation Protection in PET/CT 104 Technetium generator
    105. 105. Radiation Protection in PET/CT 105 Technetium generator
    106. 106. Radiation Protection in PET/CT 106 Radionuclide Pharmaceutical Organ Parameter + colloid Liver RES Tc-99m + MAA Lungs Regional perfusion + DTPA Kidneys Kidney function Radiopharmaceuticals
    107. 107. Radiation Protection in PET/CT 107 RADIOPHARMACEUTICALS Radiopharmaceuticals used in nuclear medicine can be classified as follows: •ready-to-use radiopharmaceuticals e.g. 131 I- MIBG, 131 I-iodide, 201 Tl-chloride, 111 In- DTPA •instant kits for preparation of products e.g. 99m Tc-MDP, 99m Tc-MAA, 99m Tc-HIDA, 111 In-Octreotide •kits requiring heating e.g. 99m Tc-MAG3, 99m Tc-MIBI •products requiring significant manipulation e.g. labelling of blood cells, synthesis and labelling of radiopharmaceuticals produced in house
    108. 108. Radiation Protection in PET/CT 108 Laboratory work with radionuclides
    109. 109. Radiation Protection in PET/CT 109 Administration of radiopharmaceuticals
    110. 110. Radiation Protection in PET/CT 110 Categorization of hazard Based on calculation of a weighted activity using weighting factors according to radionuclide used and the type of operation performed. Weighted activity Category < 50 MBq Low hazard 50-50000 MBq Medium hazard >50000 MBq High hazard
    111. 111. Radiation Protection in PET/CT 111 Categorization of hazard Weighting factors according to radionuclide Class Radionuclide Weighting factor A 75 Se, 89 Sr, 125 I, 131 I 100 B 11 C, 13 N, 15 O, 18 F, 51 Cr, 67 Ga, 99m Tc, 111 In, 113m In, 123 I, 201 Tl 1.00 C 3 H, 14 C, 81m Kr 127 Xe, 133 Xe 0.01
    112. 112. Radiation Protection in PET/CT 112 Categorization of hazard Weighting factors according to type of operation Type of operation or area Weighting factor Storage 0.01 Waste handling, imaging room (no inj), waiting area, patient bed area (diagnostic) 0.10 Local dispensing, radionuclide administration, imaging room (inj.), simple preparation, patient bed area (therapy) 1.00 Complex preparation 10.0
    113. 113. Radiation Protection in PET/CT 113 Categorization of hazard Administration of 11 GBq I-131 Weighting factor, radionuclide 100 Weighting factor, operation 1 Total weighted activity 1100 GBq Weighted activity Category < 50 MBq Low hazard 50-50000 MBq Medium hazard >50000 MBq High hazard
    114. 114. Radiation Protection in PET/CT 114 Patient examination, 400 MBq Tc-99m Weighting factor, radionuclide 1 Weighting factor, operation 1 Total weighted activity 400 MBq Weighted activity Category < 50 MBq Low hazard 50-50000 MBq Medium hazard >50000 MBq High hazard Categorization of hazard
    115. 115. Radiation Protection in PET/CT 115 Patients waiting, 8 patients, 400 MBq Tc-99m per patient Weighting factor, radionuclide 1 Weighting factor, operation 0.1 Total weighted activity 320 MBq Weighted activity Category < 50 MBq Low hazard 50-50000 MBq Medium hazard >50000 MBq High hazard Categorization of hazard
    116. 116. Radiation Protection in PET/CT 116 Category of hazard (premises not frequented by patients) Typical results of hazard calculations High hazard Room for preparation and dispensing radiopharmaceuticals Temporary storage of waste Medium hazard Room for storage of radionuclides Low hazard Room for measuring samples Radiochemical work (RIA) Offices
    117. 117. Radiation Protection in PET/CT 117 High hazard Room for administration of radiopharmaceuticals Examination room Isolation ward Medium hazard Waiting room Patient toilet Low hazard Reception Category of hazard (premises frequented by patients) Typical results of hazard calculations
    118. 118. Radiation Protection in PET/CT 118 Building requirements Category Structural shielding Floors Worktop surfaces of hazard walls, ceiling Low no cleanable cleanable Medium no continuous cleanable sheet High possibly continuous cleanable one sheet folded to walls What the room is used for should be taken into account e.g. waiting room
    119. 119. Radiation Protection in PET/CT 119 Building requirements Category Fume hood Ventilation Plumbing First aid of hazard Low no normal standard washing Medium yes good standard washing & decontamination facilities High yes may need may need washing & special forced special decontamination ventilation plumbing facilities facilities facilities
    120. 120. Radiation Protection in PET/CT 120 Design Objectives •Safety of sources •Optimize exposure of staff, patients and general public •Maintain low background where most needed •Fulfil requirements regarding pharmaceutical work •Prevent uncontrolled spread of contamination
    121. 121. Radiation Protection in PET/CT 121 VENTILATION Laboratories in which unsealed sources, especially radioactive aerosols or gases, may be produced or handled should have an appropriate ventilation system that includes a fume hood, laminar air flow cabinet or glove box The ventilation system should be designed such that the laboratory is at negative pressure relative to surrounding areas. The airflow should be from areas of minimal likelihood of airborne contamination to areas where such contamination is likely All air from the laboratory should be vented through a fume hood and must not be recirculated either directly, in combination with incoming fresh air in a mixing system, or indirectly, as a result of proximity of the exhaust to a fresh air intake
    122. 122. Radiation Protection in PET/CT 122 VENTILATION Sterile room negative pressure filtered air Dispensation negative pressure Corridor Injection room Fume hood Laminar air flow cabinets Passage Work bench
    123. 123. Radiation Protection in PET/CT 123 Alarm system Continous monitoring av air pressure gradients
    124. 124. Radiation Protection in PET/CT 124 Fume hood The fume hood must be constructed of smooth, impervious, washable and chemical-resistant material. The working surface should have a slightly raised lip to contain any spills and must be strong enough to bear the weight of any lead shielding that may be required The air-handling capacity of the fume hood should be such that the linear face velocity is between 0.5 and 1.0 metres/second with the sash in the normal working position. This should be checked regularly
    125. 125. Radiation Protection in PET/CT 125 Sinks If the Regulatory Authority allows the release of aqueous waste to the sewer a special sink shall be used. Local rules for the discharge shall be available. The sink shall be easy to decontaminate. Special flushing units are available for diluting the waste and minimizing contamination of the sink.
    126. 126. Radiation Protection in PET/CT 126 Washing facilities The wash-up sink should be located in a low-traffic area adjacent to the work area Taps should be operable without direct hand contact and disposable towels or hot air dryer should be available An emergency eye-wash should be installed near the hand-washing sink and there should be access to an emergency shower in or near the laboratory
    127. 127. Radiation Protection in PET/CT 127 Shielding Much cheaper and more convenient to shield the source, where possible, rather than the room or the person Structural shielding is generally not necessary in a nuclear medicine department. However, the need for wall shielding should be assessed e.g. in the design of a therapy ward (to protect other patients and staff) and in the design of a laboratory housing sensitive instruments (to keep a low background in a well counter, gamma camera, etc)
    128. 128. Radiation Protection in PET/CT 128 Layout of a nuclear medicine department From high to low activity
    129. 129. Radiation Protection in PET/CT 129 SUMMARY OF SPET/CT • SPECT cameras are scintillation cameras, also called gamma cameras, which image one gamma ray at a time, with optimum detection at 140 KeV, ideal for gamma rays emitted by Tc-99m • SPECT cameras rotate about the patient in order to determine the three-dimensional distribution of radiotracer in the patient • SPECT/CT scanners have a CT scanner immediately adjacent to the SPECT camera, enabling accurate registration of the SPECT scan with the CT scan, enabling attenuation correction of the SPECT scan by the CT scan and anatomical localization of areas of unusually high activity revealed by the SPECT scan

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