What small bowel dose constraints do you use in gyn brachytherapy?

There is no good outcome data available with this, although some dosimetric studies have limited 2 cc to 60-65 Gy (EQ2). That being said, it is important to monitor at each fraction the closest loop of small bowel and attempts should be made to avoid any hot spots and to spread out that dose to different loops and organs if possible. One intervention which helps with this is different filling of the bladder for each fraction for planning and treatment. This may push some of the bowel loop out for those fractions with some increase in bladder dose.

I agree with all of Sushil's comments. One thing I also like to stress is that there are two components that contribute to long term bowel health---the maximum dose received and the overall average bowel dose. Although we try to keep the 2 cc max to less than 60-65, some patients (particularly those with a loop fixed close to a post op target) may get into trouble with even these doses. However, a small bowel obstruction, even if it requires surgery, may not have a lasting effect on a patient's quality of life if it can be fixed with a simple resection and reanastomosis. The max dose tends to determine whether a patient gets an obstruction but the average dose likely determines how readily it can be fixed. For this reason, we usually use IM...

I agree with both Sushil's and Patricia's comments. If there is significant small bowel near an implant - differential bladder filling and brachytherapy fractionation can help. One of the worst complications to have is disease recurrence and, at times, exceeding these constraints may be necessary for cure.