Design optimization of a dedicated breast PET scanner using TOF imaging in a partial ring geometry

A dedicated breast PET scanner with a partial ring design can provide geometric flexibility in detector placement as well as the ability to combine with other modalities. A major challenge of a stationary partial ring scanner design with limited angle coverage is to maintain image quality and quantitative information in the tomographic image by incorporating TOF information in image reconstruction. Our aim is to optimize the scanner design for high spatial resolution and sensitivity followed by an evaluation of the timing resolution necessary to achieve high contrast in small lesions as a function of ring coverage. System design simulations were performed using a GATE Monte Carlo method for modeling TOF scanners with as good as 300 ps timing resolution. Point sources in air as well as in a water cylinder were simulated to benchmark the degradation in spatial resolution due to parallax error. For a realistic imaging situation we also simulated a lesion phantom containing spheres with two different uptakes relative to the background and CRC was measured for each hot sphere. We find that using TOF information leads to reduce artifacts in a partial ring detector design and helps to achieve more accurate image reconstruction. Our results also show that using a spatially variant PSF model or incorporating DOI capable detector leads to improved and more uniform spatial resolution and CRC over the whole FOV. Additional work is ongoing to study the impact of the PSF modeling or/and DOI capable detector design in a partial ring scanner for reduced parallax error.