I contour entirety of uterus as CTV in EBRT regardless of whether they have uterine involvement or not, so I'm not sure how uterine involvement changes management. Doesn't change staging.
Lots of bowel superior to the superior edge of uterus, coplanar with external, internal, and common iliac lymph nodes in most cases.
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I've placed the blue line at top of L5 as per your post. That seems like a lot more bowel (bag contoured as light green) than 'literally nothing' that can be spared. This is a mostly midline sagittal view, a little offset to show the fundus of the uterus (which curved to patient's right).
Granted, the bowel that is coplanar with uterus is surrounded by LN ptvs, so from say S3 down, I agree, not a lot of sparing as the bowel there is surrounded by PTV on other planes. This patient had a + LN that is not in plane on current image.
How often do you have to give your cervix patients anti-diarrheals? For me it's very very rarely. Daily CBCT for IGRT.
Granted, I have one attending who does IMRT for every case and another who does 4-field box for node negative patients, but they'll both do full IMRT with SIB for anybody LN positive, with or without PA coverage.
I also don't like sequential boosts for LNs, but that's just a my preference thing and I see it in the community all the time, so as long as you're taking to a higher dose, do your thing.