If the goal is reducing small bowel dose, one should use a belly board and treat in prone position. There was a systematic review in the Green Journal regarding this. It's also beneficial when treating with IMRT, as seen in this publication.

I agree and would add that prone without the belly board with a full bladder if a bellyboard is not available is better than supine. We just use CBCT first 3 days then weekly or so to assess the bladder filling and get  rough idea if more filling would be better. Any bowel displacement is great...

I agree. We did a little in-house study on a few patients (never published) comparing 3D to IMRT and prone to supine. 3D vs IMRT had minimal impact on small bowel dose compared to prone vs. supine, which had a much larger impact. This is not surprising, as there is only so much IMRT can accomplish i...