TITLE: Theoretical Implications and Design Principles of Focused Multi-Pinhole SPECT
AUTHORS: Yuchuan Wang, David Graff, Greta Mok, Benjamin Tsui
PURPOSE: We study, in theory, the advantages and implementations of focused multi-pinhole (FMPH) SPECT, in which, all of the pinhole apertures are tilted towards a common rodent-sized field-of-view (FOV) for maximum gain in detection efficiency.
METHODS AND MATERIALS: First, we establish two equations using system design parameters: one describes the photon detection efficiency (PDE), the other describes how well the Tuy's condition is satisfied within the FOV (defined as TSE: tomographic sampling efficiency). Among "resolution-equivalent" system designs with minimal projection-overlap, we show that the number of unknowns in the PDE equation is reduced to two: the number of pinholes (N) and the system radius-of-rotation (R) while maintaining a non-truncated FOV.
RESULTS: For a typical rodent imaging configuration of 26mm FOV and 25mm minimum R, to achieve a target resolution of 1.2mm, PDE maximization for a clinical SPECT camera (40cm detector size, 3.5mm intrinsic resolution) resulted in N=8, R=25mm, D=0.8mm, F=12 cm, and 4 times PDE over a resolution-equivalent optimal SPH design. For a modular camera (12cm detector, 1.5mm intrinsic), we obtain N=4, R=25mm, D=0.6mm, F=5cm, and 1.8 times PDE over the optimal SPH design.
CONCLUSIONS: FMPH SPECT may be a superior imaging method as compared to SPH SPECT in practical rodent imaging studies. We developed effective means of optimizing the FMPH design based on maximizing both photon detection efficiency and tomographic sampling efficiency.
FUNDING SOURCES: NIH R01 EB 001558