PURPOSE Deformable image registration (DIR) is necessary for accurate dose accumulation between multiple radiotherapy image sets. DIR algorithms can suffer from inverse and transitivity inconsistencies. When using deformation vector fields (DVFs) that exhibit inverse-inconsistency and are nontransitive, dose accumulation on a given image set via different image pathways will lead to different a...

BACKGROUND Owing to adverse pharmacokinetics, azathioprine treatment may fail to induce a satisfactory clinical response in systemic connective tissue diseases. The major intracellular cytotoxic metabolites of azathioprine are 6-thioguanine nucleotides (6TGNs). METHODS To assess whether the erythrocyte accumulation of 6TGN is a clinically applicable index for monitoring azathioprine treatment...