Feasibility study of MLEM-based iterative reconstruction for three-dimensional coded aperture imaging

Coded aperture imaging is commonly used in radioactive imaging for applications such as radioactive localization, nuclear medicine imaging, and nuclear fuel transport monitoring. In this study, a three-dimensional coded aperture imaging system constructed using multiple modules was proposed, and the MLEM iterative algorithm was employed to reconstruct the source distribution. The feasibility of the proposed method was validated through the reconstruction of four distinct types of radioactive source distributions. In addition, this work introduces a practical method for determining the required iteration number ( k ) and total gamma counts ( N c ) by utilizing RMSE and MSE that depend solely on k and N c . This method provides guidance for k and N c selecting in experimental applications to ensure that the image quality (UQI) reaches saturation. • Developed a direct three-dimensional coded aperture imaging method. • Proposed a method to assess if counts and iterations saturate image quality. • Complex sources need higher counts and more iterations for MLEM 3D imaging. • Increasing imaging modules improves 3D image quality more than higher counts.