Scatter-compensated geometrical components for detector normalization in whole-body PET

On a PET scanner consisting of block detectors, coincidence responses to scattered radiation may differ from those to trues depending on the crystal pair position within a coincidence block pair. Furthermore, these differences are considered to vary according to the radial position of the coincidence block pair. In component-based normalization, a scatter-compensated geometrical component is therefore required in addition to the scatter-compensated block-profile and intrinsic crystal efficiencies. In this study, we propose a scatter-compensated component-based normalization scheme using an annulus phantom which provides true and scattered radiations over a large transaxial field-of-view. We evaluate the normalization accuracy using three different-sized phantoms with whole-body PET. Results showed that the proposed normalization method significantly reduces the ringing artifacts in reconstructed images with different scattered/true fractions. The proposed algorithm worked well under different scattered/true radiation conditions, and was considered to be a practical normalization method in whole-body PET.