Dose rates for brachytherapy applicators using ¹³⁷Cs sources

We have computed the dose rates from brachytherapy 3M ¹³⁷Cs sources for different size ovoids and vaginal cylinders. They are expressed in tabular form. The dose rate tables thus generated compared with the widely used tables for ²⁶⁶Ra differ by as much as 9% for ovoids and up to 20% for the cylinders.^' These differences are mainly a consequence of differences in physical structure of the two types of sources. These tables will serve as a quick guide and reference and should be of great practical use to physicists and radiotherapists for planning implants. However, these tables are not meant to replace detailed computer isodose calculations.