A Feasibility Prototype of a Low-dose Stationary Tomographic Molecular Breast Imaging Camera Using 3D Position Sensitive CZT Detectors

A novel Molecular Breast Imaging system (MBI) is being developed by Kromek and University College London. MBI systems have been shown to provide excellent results in patients with dense breasts, but higher than mammography patient dose and long imaging time of 40 min impede their wide adoption. The design is based on a pair of opposing CZT detector arrays and high-density multi-pinhole (MPH) collimators. The new system combines superior energy and position resolution and depth of interaction (DOI) sensing of CZT detectors, wide range angular sampling of MPH collimators and novel de-multiplexing image reconstruction techniques to deliver tomographic images with stationary detectors. The new system is expected to mitigate the MBI drawbacks without compromising diagnostic content.Following the initial evaluation, a new feasibility prototype using upgraded ASIC and new front-end electronics was designed, built, and characterised. New image reconstruction and de-noising algorithms were developed on simulated data to improve the Contrast-to-Noise (CNR) ratio and reduce the fluctuations in the correlated background noise associated with MPH image reconstruction. The collimator geometry was further optimised by including non-local means noise filtering which increased the CNR by almost a factor of 3. The current results indicate that we can achieve the dose reduction to the mammography level, reduce the minimum size of detected lesions to about 6 mm and have an additional potential for reduction of the measurement time.