Design of high sensitivity, high resolution compact single photon imaging devices for small animal and dedicated breast imaging

Imaging the biodistribution of single photon emitting radiotracers in small animals and in the breast with high resolution and high sensitivity is an important challenge. Recent work has shown that single photon emission computed tomography (SPECT) imaging of small objects with coded aperture collimators and iterative image reconstruction may provide an order of magnitude increase in sensitivity yet maintain high spatial resolution. We propose a new system design with compact detectors for single photon small animal and breast imaging. Key features are: 1) multipinhole masks for improved sensitivity, 2) pixellated NaI(Tl) scintillator arrays with small crystals for high resolution and 3) flat panel or flangeless compact position sensitive photomultiplier tubes. Analyses for a small animal device with four 10 cm×20 cm detectors and 1.5 mm detector resolution show that 0.9-1.3 mm resolution in image space could be achieved with high sensitivity for pinholes with 0.5-0.8 mm effective diameters. A design for a breast imager incorporates larger multipinhole masks, 20 cm×20 cm pixellated detectors and lower magnification. A predicted image resolution in the center of the field of view is 1.9 mm for 0.8 mm pinholes. Additional modeling, iterative image reconstruction tests and device component tests are desirable to optimize device specifications prior to detector construction.