133Xe for the in vivo X-ray fluorescence measurement of platinum.

In vivo measurements of platinum are important for studying the pharmacokinetics of platinum-based cytotoxic drugs. The technique of in vivo X-ray fluorescence can be utilized for such measurements. The feasibility of using 133Xe in near-backscatter (almost 180 degrees ) geometry has been investigated and results compared to phantom measurements made using 99Tcm in the same experimental set-up. An improvement in minimum detection limits is observed for all phantom depths less than 25 mm.