Optimization of a Stationary Tomographic MBI System Including Non-Local Means Filtering

A novel stationary tomographic Molecular Breast Imaging (MBI) system is currently under development, with the aim of obtaining high image-quality with low dose and short scanning time. The system is based on dual opposing CZT detector arrays and multi-pinhole collimators. We have recently modified the iterative image reconstruction procedure by incorporating a novel relaxation scheme, in order to make the image contrast and noise properties more uniform throughout the field-of-view. In addition, we have introduced a post-reconstruction image denoising step based on the non-local means (NLM) filter. In view of the significant effect that these steps had on the image quality, we performed a new system parameter optimization. The parameters investigated were pinhole size, opening angle and separation, as well as the number of reconstruction iterations and the degree-of-smoothing parameter of the NLM filter. The optimization was performed based on simulated data, by maximizing the contrast-to-noise ratio (CNR) in the images. We found that the optimal system parameters were not so different with the new data processing steps as compared to previous results, while the CNR was improved by a factor > 3.