ABSTRACT
CONTENTS 12.1 Introduction 186 12.2 Physics Review and Data Acquisition 187
12.2.1Physics of PET Imaging 187 12.2.2Attenuation, Absorption, and Scattering 189 12.2.3Electronic Collimation 189 12.2.4 Detectors 190 12.2.5 Time-of-Flight 190
12.3Rebining in 2D and 3D Sinograms 191 12.4Overview of Reconstruction Methods 195 12.5Analytical Reconstruction Methods 196
12.5.12D Reconstruction 196 12.5.1.1Line Integral Model and 1D Projection 197 12.5.1.22D Back Projection 198 12.5.1.3Fourier Slice eorem 198 12.5.1.42D Filtered Back Projection 199
12.5.23D Reconstruction 200 12.6Iterative Reconstruction Methods 202
12.6.1Algebraic Reconstruction Technique 203 12.6.2Statistical Method 204
12.7Conclusion and Discussion 206 References 207
The core principle of nuclear medicine is to administer a radioactive substance (also called radiotracer or simply tracer) to patients. e tracer can be injected, inhaled, or under certain circumstances, ingested. Tissues will absorb the tracer in proportion to a physiological process. e normal distribution of the tracer is subject to be aected by a physiopathological process. Examples of such processes include bone fractures, the growth of malignant tumors, and low blood ow in the heart. As it reects organ metabolism, this modality is frequently called functional imaging. Tomography in this context is called emission tomography (ET). e reconstruction corresponds to the recovery of the three-dimensional (3D) distribution of the tracer in the body. Reconstructed volumes in ET will therefore highlight if/where a given physiological process occurs. ere are two kinds of emission tomography technologies in nuclear medicine. Single-photon emission computed tomography (SPECT) makes use of a gamma emitter, that is, photons, as a radiotracer. Positron emission tomography (PET) makes use of positron emitters. It is becoming the main modality in nuclear medicine departments. is is why, in this chapter, we focus on this modality only. e most common clinical applications of ET are in oncology, and to a lesser extent neurology and cardiology.
