ESTRO Brachytherapy for Prostate Cancer 2018

⚫ 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]