Positron emission tomography: physical models and reconstruction issues

Positron emission tomography (PET) is an imaging modality that forms images of the concentration of an injected radio-pharmaceutical. These images can be combined with appropriate physiological models and ancillary measurements to yield images of physiological parameters such as perfusion, metabolic rates, receptor characteristics etc. Although images are usually reconstructed with the convolution-backprojection algorithm used in X-ray CT, there are several important differences in the data. Effects such as attenuation, Compton scatter, accidental coincidences, and detector efficiency must be accounted for. These effects are described and the key problems encountered in image reconstruction are discussed in this paper