How would you approach definitive prostate radiation in a patient with evidence of seminal vesicle invasion on MRI, but with adjacent small bowel?

This is a situation where I find an HDR boost can be very advantageous. In most patients I have found that the catheters can easily be placed into at least the first 3 cm of the seminal vesicles, often further. The advantage of HDR over LDR is two fold in this scenario. First, one can manipulate the dose with greater precision and less dependence on seed deposition. Secondly, the bladder can be filled via the Foley catheter to displace the adjacent small bowel during the treatment delivery.

I wi...

This is a problem we encounter more often in the post-prostatectomy setting, but occasionally in patients with an intact prostate, too. The major options for displacing the small bowel would include treating with a full bladder, using a rectal balloon or treating prone. A spacer is really intended to separate the rectum from the prostate, and is unlikely to have much impact on the small bowel position, as the spacer will be retroperitoneal and the small bowel will be intraperitoneal. In the end,...

First I would repeat the CT simulation to confirm that the positioning of the small bowel in relation to the seminal vesicles. If you see that the small bowel positioning varies from one scan to the next, then you can be more comfortable that the same segment of bowel will not sitting adjacent to the seminal vesicles. In that case, you could go ahead and treat the seminal vesicles as you normally would. If the repeat CT simulation confirms that the same segment of bowel is lying adjacent to the ...