Resolution recovery for list-mode reconstruction in SPECT

The purpose of the study was to evaluate the resolution recovery in the lis t-mode iterative reconstruction algorithm (LMIRA) for SPECT. In this study we compare the performance of the proposed method with other iterative reso lution recovery methods for different noise levels. We developed an iterati ve reconstruction method which uses list-mode data instead of binned data. The new algorithm makes use of a more accurate model of the collimator stru cture. We compared the SPECT list-mode reconstruction with MLEM, OSEM and R BI. all including resolution recovery, For the evaluation we used Gaussian shaped sources with different FWHM at three different locations and three n oise levels. For these distributions we calculated the reconstructed images for a different number of iterations. The absolute error for the reconstru cted images was used to evaluate the performance. The performance of all fo ur methods is comparable for the sources located in the centre of the field of view. For the sources located out of the centre, the error of the list- mode method is significantly lower than that of the other methods. Splittin g the system model into a separate object-de pendent and detector-dependent module gives us a flexible reconstruction method. With this we can very ea sily adapt the resolution recovery to different collimator types.