“…There are many choices involved in a dosimetry calculation, from the techniques used to define volumes of interest, to the fitting of time activity curves and choice of dose S-factors or kernels, where each choice will affect the outcome. Dosimetry comparison exercises of different systems based on patient data highlight relative differences, but are weakened by the fact that when using patient data, the inherent ground truth is unknown [1] , [2] . A recent overview of commercial treatment planning systems (TPS) for MRT recognized the need to assess uncertainty in the dosimetric process and noted that the impact on TPS results still needs to be assessed [3] .…”