@jeffmarc My RO said you don’t use it in SRT because cancer cells could be near the rectum and you need to get those too.
A barrier could actually protect these cells from the disruptive effects of the radiation. When your simulation is done under optimal conditions (full bladder/enema) the rectum is fairly collapsed; this allows them to get into that area directly adjacent and around the rectum so that the software of the radiation machine can actually ‘shape’ the beam to go around the rectum.
This is how my RO explained it and it sounds pretty cool when you think about it.
But this is why it is SO important to follow the dictum of ‘full bladder/empty rectum’…if your bladder isn’t distended enough or your rectum isn’t narrow enough (due to gas or feces), those beams are going to hit tissues that weren’t meant to be hit and that can cause cystitis and proctitis…Best,
Phil