Attenuation, Scatter, and Spatial Resolution Compensation in SPECT

This chapter explains methods of correcting for complicating factors in the single-photon emission computed tomography (SPECT) image reconstruction process, namely, attenuation and scatter. SPECT imaging is not ideal. Inherent in SPECT imaging are degradations that distort the projection data. This chapter focuses on three such degradations and the compensation for them. The first is attenuation- in order for a photon to become part of a measured projection, it must escape the body, the second source of degradation is the inclusion of scatter in the projections, and the third source of degradation is the finite, distance-dependent spatial resolution of the imaging system. It is noted that, solely compensating for attenuation is not enough to improve SPECT image quality to its fullest extent. Instead, attenuation, scatter, resolution, correction of patient, physiological motion, and changes in localization during the course of acquisition, can impact image quality, and thus combined compensation is required.