University of Washington
Introduction to PET Physics

1. Introduction
2.1 Introduction
2.2 Positron emission and annihilation
2.3 Coincidence detection and electronic collimation
2.4 Photon interactions in human tissue and correction for gamma-ray attenuation
2.5 Types of coincidence events
3.1 Principles of operation
3.2 Sensitivity to true coincidence events
3.3 Sensitivity to scattered events
3.4 Sensitivity to random events
3.5 Effect of camera geometry
4.1 Introduction
4.2 Notation and mathematical theorems used
4.3 Analytic image formation in 2D PET
4.4 Filtered Back-Projection in 3D and 3D-RP
5.1 Introduction
5.2 Scintillators and scintillation detectors
5.3 Pulse processing
5.4 Coincidence processing
5.6 Block detectors
5.7 Camera configurations in PET
6.1 Introduction
6.2 Attenuation correction
6.3 Correction for random coincidences
6.4 Scatter correction
6.5 Detector normalisation

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List of Figures

 Figure 1 Positron emission and annihilation Figure 2 Coincidence detection in a PET camera Figure 3 Variation of point source response function (psrf) with position P in SPECT and in PET Figure 4 Coincidence detection in an attenuating object Figure 5 Types of coincidences in PET Figure 6 Axial cut-away view of a multi-ring PET camera (not to scale) operating in 2D mode, showing direct and cross-plane rebinning Figure 7 Axial cut-away view of a PET camera in 2D and 3D mode showing how the number of possible LORs can increase when the septa are removed Figure 8 Predicted sensitivity from the number of LORs used in 2D and 3D mode Figure 9 Effect of septa removal on sensitivity to scattered coincidences Figure 10 Effect of septa removal on sensitivity to single events Figure 11 3D co-ordinate system for a full-ring PET camera Figure 12 Projections generated from a single central point source (3 projections shown) Figure 13 Back-projections of a point source. With finite numbers of back-projection angles, "star" artefacts are seen Figure 14 The Ramp and Hanning filters Figure 15a Parallel projections in 2D. Note that he LORs become closer together towards the edge of the FOV. To correct for this, the data must be re-sampled (arc corrected) prior to reconstruction Figure 15b Parallel projections in 3D Figure 16 Axial cut-away diagram of a PET camera operating in 3D mode, showing the extent of the projection sets as a function of angle j Figure 17 Features of a typical energy distribution for electrons involved in interactions with 511 keV photons Figure 18 Features of a typical energy distribution measured by a scintillation detector system exposed to 511 keV photons Figure 19 Schematic diagram showing coincidence processing in a PET camera Figure 20 A block detector

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List of Tables

 Table 1 Examples of radiotracers and their applications Table 2 Properties of commonly used positron emitting radio-isotopes Table 3 Notation for spatial and Fourier quantities Table 4 Examples of scintillators and their properties

 Last revised by: Ramsey Badawi Revision date: 12 Jan 1999