Bremsstrahlung radiation dose in yttrium-90 therapy applications.

Abstract

The bremsstrahlung component of the decay scheme of beta emitters has been traditionally ignored in internal dosimetry calculations. We have estimated the radiation dose from the bremsstrahlung component of the decay scheme of 90Y as a function of distance from a point source in a liquid medium and to body organs from distributed sources of 90Y in the liver and spleen. These estimates agree with measurements of bremsstrahlung dose measured in a Rando phantom, and give an estimate of the importance of this contribution to the overall dosimetry. The bremsstrahlung radiation absorbed dose contribution from an organ to itself is very small compared to that from the beta dose, but the contribution to other organs is not always negligible, especially when large amounts of 90Y may be involved, as in therapy applications.