Reconstruction of Time-of-Flight Projection Data with the STIR reconstruction framework

This manuscript gives an update on the integration of Time-Of-Flight reconstruction into the STIR image reconstruction toolkit. In this iteration we provide significant support to reconstruct TOF-compatible projection data. Most infrastructure classes, such as ProjDataInfo and ProjData, have been extended, and utilities, as lm_to_projdata, used to create sinograms from listmode data, can now handle TOF information. This extension required many modifications in the low level code base of STIR, making it non-trivial and error-prone. Therefore, a thorough validation is required. In this work we provide initial results of the correctness of the extension. Using Monte Carlo simulations, as well as cylindrical and XCAT phantoms analytically projected, we calculate the contrast recovery ratio over a wide range of iterations. The results demonstrate the benefits of TOF under different configurations, which are in good agreement with literature. The ROI mean value converges to the maximum faster with better timing resolution, while larger number of TOF bins improve contrast values in low iterations.