667 / 884
⚫
Moving seeds from 5mm to 3mm from the edge increases
maximum rectal dose by 17%.
⚫
Posterior seeds 3mm from edge:
- 1mm margin: 187
6Gy;
1% (max. rectal dose; % late rectal toxicity)
- 2mm margin: 222
8Gy;
2%
- 3mm margin: 257
11Gy;
3%
-4 mm margin: 292
14Gy;
5%
-5mm margin: 327
17Gy;
7%
[Waterman et al.; Int J Radiat Oncol Biol Phys, 2003]