- 1. SPECT
2. Principles of SPECT
- Single photon emission computed tomography
(SPECT) is a nuclear medicine imaging technique
using gamma rays.
- Images primarily the biological process or function
of organs rather than anatomical structure.
- Uses a gamma camera to acquire multiple 1D
projection images which are then processed and
converted into 2-D images using the mathematical
technique of computer tomography.
- Multiple slices are obtained simultaneously
and stacked to form a 3D representation.
- To acquire the images, the gamma
camerais rotated around the patient.
Projections are typically acquired every
3-6 degrees. Generally, a full 360 degree
rotation is used to obtain an optimal
- Multi-headed gamma cameras can provide
- 15 20 seconds is the typical time to obtain each
4. projection. This givesa total scan time of 15-20 minutes. 5. A nuclide in a radiopharmaceutical is placed into the body by either injection, oral or inhalation. It consists of an emitting isotope.
- Photons travelling in the desired direction pass through the collimator towards the detector; other photons are absorbed by the collimator.
Aston Medical Imaging test page 87
Radiation detectors for medical applicationsBy Stefaan Tavernier, Boris Grinyov
- A gamma ray photon interacts with the detector (NaI:Tl crystal) by means of the Photoelectric Effect or Compton Scattering with the iodide ions of the crystal.
7. This interaction causes the release of electrons which in turn interact with the crystal lattice to produce light, in a process known as scintillation.http://www.physics.ubc.ca/~mirg/home/tutorial/hardware.html
- These photons are then detected by a collection of photomultiplier tubes (PMTs)
9. Relative reading from the PMTs are used to compute the spatial coordinates of the gamma rays 10. Each PMTs outputs an electrical current proportional to the number of light photons detected.Radiation detectors for medical applicationsBy Stefaan Tavernier, Boris Grinyov
12. History of SPECT
- 1940's crude spatial information about radioactive source distributions within the brain were produced using a single detector positioned at various locations around the head.
13. 1951 Ben Cassen invented the rectilinear scanner. 14. It produced planar images by mechanically scanning a detector in a raster-like pattern over the area of interest. 15. Only photons directly under the moving scanner could be detected at any given time 16. Long Imaging times 17. 1953 Hal Anger reported the first gamma camera 18. It used a pin-holeconfiguration 19. Produced images on a large piece of photographic paper 20. Long exposure times and high radiation doses. http://www.physics.ubc.ca/~mirg/home/tutorial/history.html
21. History of SPECT
- 1957Anger replaced the film and screen with a single NaI crystal and PMT array. This was the first Anger scintillation camera
22. Modern Anger Cameras use a lead collimator perforated with many parallel, converging or diverging holes instead of the original pin-hole configuration. 23. Resolution is determined by size of collimator holes 24. 1963 Kuhl and Edwards presented for the first time, tomographic images produced using the Anger Camera http://www.physics.ubc.ca/~mirg/home/tutorial/pics/camera2.gif
25. History of SPECT
- 1977Everett, Fleming, Todd and Nightengale suggested the use of the Compton effect for gamma-radiation imaging
26. 1980sFASTSPECT 27. Incorporates an array of gamma-ray cameras to simultaneously record enough planar images without camera motion. 28. All projections are collected at the same time, so total data-collection period is that required for a single planar image. 29. Too complex and high increasein price 30. 1983 Manbir Singh and David Doria proposed and experimented the use of the Compton Camera for SPECT because: 31. Mechanical collimation is replaced with electronic collimation 32. Huge gains in sensitivity (this compromises resolution) 33. Reduction in radiation dosageFASTSPECT
34. History of SPECT
35. 16-camera small-animal SPECT imager built with modular scintillation cameras 36. Enough modular cameras to collect entire data set without camera or imaging subject motion 37. Enlarged camera active area with larger PMT array 38. Lead-shielded enclosure 39. Improved calibration and positioning system 40. Specifically designed for small-animal imaginghttp://search.vadlo.com/b/q?rel=2&keys=PPT+about+FastSPECT
41. History of SPECT
- 2008Shinji Motomura et al Spectrom, demonstrated the feasibility of compton cameras for multiple molecular imaging. Camera has:
42. Two double-sided orthogonal-strip germanium detectors 43. Their excellent energy resolution enables discrimination of the nuclides 44. Accurate determination of the scattering angle for rays in wide energy rangehttp://www.rsc.org/publishing/journals/JA/article.asp?doi=b802964d
45. History of SPECT
- 2010 ProSPECTusdesigned by the University of Liverpool's Nuclear Physics research group alongside the Nuclear Physics Group at STFC Daresbury Laboratory
46. Improving future diagnosis of cancer and the probability of successful cancer therapy. 47. Technology based on Compton Camera 48. Much less of the radiation used in the process is wasted 49. 100 times more sensitive than existing clinical SPECT systems. 50. Increased sensitivity offers two benefits 51. dose of radiation administered to the patient could be reduced or 52. alternatively more patients could be scanned by one machine in a day if the current dose is used.http://www.sciencedaily.com/releases/2010/03/100303113956.htm
U-SPECT is an application that is used for veterinary purposes rather than normal medical purposes
Dynamic single positronemission computed tomography(D-SPECT) is a new technology used to improve theresolution and specificity
55. SPECT Applications
56. Brain Imaging 57. Renal Imaging 58. Bone Scans 59. Parathyroid Scanshttp://radiographics.rsna.org/content/28/5/1461/F13.large.jpg
60. Heart Imaging
61. Diagnose a heart attack 62. Predict probability of a heart attack 63. Assess a patients condition afterbypass surgery or angioplasty 64. Additional applications include SPECT myocardial perfusion imaging (MPI)http://interactive.snm.org/index.cfm?PageID=5210
65. Brain Imaging
- Help differentiate between types of dementia
66. Help clinicians study Alzheimer's Disease 67. Identify specific areas of the brain affected by trauma 68. Identify effects of medication and drugs on the brain 69. Identify areas affect by seizures and toxicsDrug Abuse
70. Renal Imaging
SPECT scan can
71. Damaged areas in kidneys 72. Glomerular flow ratehttp://www.amenclinics.com/brain-science/spect-research/
73. Non-Medical Application Gamma-Ray Spectrometer(GRIS)
74. Mapping radio active contaminationhttps://www.llnl.gov/str/September04/Labov.html
76. Good Image Contrast 77. Physical and Functional imaging that is accurate and reliable for diagnostics 78. Cardiac Gated Acquisitions are possible with SPECT 79. High diagnostic ability for bone scintigraphy com pared to MRIhttp://www.nupecc.org/iai2001/report/B22.pdf