CD33 and leukemia: In human clinical trials, in an article dealing more specifically with the pharmacokinetics and dosimetry [30] of 213Bi-labelled anti-CD33 antibody used in a leukaemia RIT clinical trial, doses are calculated from images and are given in Sv rather than Gy because a multiplication factor of 5, corresponding to the RBE of alpha particles, is included in the dose calculation.