IMRT SX1

Name (ID): SBRT, PROSTATE (AAMD_RSS2016PS)
Plan or PlanSum ID: SBRT12fld40Gy

When attempting an IMRT plan for this case, the 6X FFF energy proved to be a challenge when when trying to repect the skin dose constraints set out in the scoring metric.  Twelve (12) gantry positions were used in an attempt to spread out the skin entry dose, and unique collimator rotations were employed to help minimize the effect of 1cm leaves.  Collimator rotations were selected during a beams eye view analysis often aligning to either the neurovascular bundles or the rectum (areas where sharp dose gradient or fine modulation were required).  As a result, the 12 field IMRT plan was able to score within 1 point of the VMAT attempt, however, since 12 fields were employed the treatment time, while still very fast for a 12 field plan delivering 8 Gy in a single fraction, it was still longer than a 4 arc plan delivering the same dose to the target.  As is the common theme, VMAT seems to be the clear choice when employing SBRT/SRS (<=5fx) type treatments.  Static field IMRT seems to make similar or higher quality plans than their VMAT equivalent plan in a similar treatment time on most standard fraction targets, while being faster to optimize.

This prostate SBRT plan shows nice dose gradients. Hot spots are successfully off the urethra. Bowel/rectum constraints are all met. This is a clinically acceptable plan.

_{Any reference to a "plan study" are simply what the organizers call each case and may not be a "study" in the FDA sense as they may not have been published in a peer reviewed journal.
Varian does not provide medical advice and these are illustrative examples only.
Leading plans by expert planner. Your results may vary.}