Table of Contents

1. Introduction

2. The physical principles of PET

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. 2D mode and 3D mode

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. Image reconstruction

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. Detection systems in PET

5.1 Introduction
5.2 Scintillators and scintillation detectors
5.3 Pulse processing
5.4 Coincidence processing
5.5 Dead-time
5.6 Block detectors
5.7 Camera configurations in PET

6. Corrections for quantitative PET in 2D and 3D mode

6.1 Introduction
6.2 Attenuation correction
6.3 Correction for random coincidences
6.4 Scatter correction
6.5 Detector normalisation
6.6 Dead-time correction

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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

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