Image reconstruction for rotational modulation collimator (RMC) using non local means (NLM) denoising filter

A rotational modulation collimator (RMC) is an indirect imaging technique for locating remote radiation sources. However, when the counts of detected radiations are low, the RMC generates artifacts in the reconstructed images. To solve this problem, we propose a new reconstruction algorithm. Our algorithm removes noise in an RMC modulation pattern using a variance stabilization transformation and a non-local means filter. We verify that the proposed method enhances the performance of the reconstructed images through experiments with Monte Carlo simulation data. •Standard MLEM reconstruction method can introduce artifacts in the RMC images.•Proposed reconstruction method can reduce artifacts and improve RMC image quality.•Proposed method removes noise in RMC data while preserving structural information.•Our asymmetric mask design eliminates the 180°ambiguity from RMC images.