For post-prostatectomy radiation, what rectum, sigmoid, and bladder constraints do you use?  

In these cases, I follow consensus guidelines for contouring the CTV_ProsBed and also contour out the sigmoid and any small bowel. I use whole organ volumes, not just wall contours, although there are published constraints for the rectal wall and bladder wall. There are a range of appropriate const...

It's a great question, and definitely occurs from time to time, sometimes with sigmoid, and sometimes with a loop of small bowel! I may be overly cautious, but I follow the "first do no harm" principle. First, I make sure the clinical setup is optimized - is sigmoid in the same position on MRI (whic...