Methodology and Performance Assessment of Zoom SPECT

Abstract

The methodology of zoom single-photon emission computed tomography (Z SPECT) imaging and its performance was assessed using two tomographic gamma cameras, systems A* and B†, fitted with high resolution collimators. The center of rotation (COR) varied linearly for zoom factors (ZF) from 1.0 to 4.0. It was more stable and reproducible in system B and its variation with ZF was significantly smaller. Z SPECT acquisitions were done using projection matrix sizes 64 × 64 and 128 × 128, 64 projections over 360 degrees and ZF equal to 1.0, 1.6 and 2.0. Point source acquisitions demonstrated the superior performance of system B. Two small phantoms were constructed (10 × 10 × 5 cm each) containing cold rods and hot rods. The use of zoom improved both contrast and resolution. The Nowak reconstruction algorithm provided better contrast than the conventional filtered backprojection algorithm. The 2 mm hot rod was visible using system B with projection matrix 64 × 64 and ZF = 1.6. The use of zoom in SPECT leads to improved contrast and resolution; the application of Z SPECT to small organs is recommended.