Investigation of breast cancer detectability using PET insert with whole-body and zoom-in imaging capability

Traditional whole-body PET scanner is limited in resolution due to large detector crystal size, finite positron range and non-collinearity of annihilation photons. Our lab has developed a prototype half ring insert PET system that can improve resolution and radionuclide contrast recovery by using (1) smaller size of the detector crystals (2) virtual pinhole PET geometry obtained by placing the insert close to the imaging subject. This design allows for zooming-in to an area of interest while still maintaining the scanners whole-body imaging capability. To find the limits of the image resolution and contrast recovery, we performed a set of Monte Carlo simulations for a clinical PET system with and without half ring insert. The reconstructed images show the improvement in image resolution, with 3 mm diameter tumors resolvable with insert at a contrast ratio of 9:1, compared to scanner without insert where smallest tumors resolvable was 6 mm.