It is important to note that Cs-131 has a higher energy than I-125 or Pd-103 and therefore one should design a plan that takes advantage of this difference. The higher energy allows the planner to keep sources further away from the rectum than is possible with I-125 or Pd-103 and in fact one should not use the 3-4 posterior template holes directly above the rectum. The increased energy also allows the planner to achieve adequate dosimetric coverage of margins without extensive use of extracapsular seeds.

Lastly, remember to consider the enhanced sensitivity of critical structures that may result from the increased dose rate.