Biomedical Engineering Reference
In-Depth Information
Chapter4
BasicsofPETandSPECTImaging
Ralph A. Bundschuh and Sibylle I. Ziegler
Rechts der Isar Hospital, Technical University of Munich, Munich,
Germany
4.1
Introduction ::::::::::::::::::::::::::::::::::::::::::::::::::::::
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4.1.1
Interaction of photons with matter ::::::::::::::::::::::
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4.1.1.1
Photoelectric eect :::::::::::::::::::::::::::
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4.1.1.2
Compton scattering ::::::::::::::::::::::::::
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4.1.2
Photon attenuation ::::::::::::::::::::::::::::::::::::::
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4.1.3
Scatter :::::::::::::::::::::::::::::::::::::::::::::::::::
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4.1.4
Variation in detector eciency, normalization ::::::::::
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4.1.5
Dead time effects (loss of count rate) (PET and
SPECT) ::::::::::::::::::::::::::::::::::::::::::::::::::
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4.1.6
Partial volume eects (PET and SPECT) ::::::::::::::
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4.1.6.1
Spill out ::::::::::::::::::::::::::::::::::::::
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4.1.6.2
Spill in ::::::::::::::::::::::::::::::::::::::::
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4.1.7
Time resolution and randoms (PET only) ::::::::::::::
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4.1.8
Collimator eects|Distance dependent spatial
resolution (SPECT only) ::::::::::::::::::::::::::::::::
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4.1.9
Positron range and annihilation (PET only) ::::::::::::
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References :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
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4.1 Introduction
In the last years, quantitative imaging for preclinical as well as for clinical
use became more and more important, mainly in oncology but also in neu-
rology and cardiology. PET and SPECT are imaging modalities facilitating
quantitative in vivo measurements. For exact quantification, several effects
degrading the acquired data have to be taken into account. Some of these
effects, such as detector eciency, partial volume effects, photon attenuation
and scatter, are found in SPECT as well as in PET imaging. In contrast,
the collimator-detector response occurs only in SPECT and random coinci-
dences or limitations due to positron range are specific for PET. This chapter
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