Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
To investigate the effect of an endorectal balloon (ERB) on anal wall (Awall) and rectal wall (Rwall) doses in high-dose post-prostatectomy intensity-modulated radiotherapy (IMRT).
For 20 patients, referred for salvage IMRT after prostatectomy for prostate cancer, two planning CT-scans were performed: one with and one without an air-filled ERB. A planning target volume (PTV) was defined, using international guidelines. Furthermore, the Awall and Rwall were delineated. In both the scans, IMRT plans were generated with a prescribed dose of 70Gy. The mean dose (Dmean), maximum dose, minimum dose, and volumes exposed to doses ranging from ⩾20 to ⩾70Gy (V20-V70) to the Awall and Rwall were calculated. Finally, inner Rwall surface areas exposed to doses ranging from ⩾20 to ⩾70Gy (A20-A70) were calculated. Dose-parameters were compared between plans with and without ERB.
All Awall parameters, except V70, were significantly reduced by the ERB with an overall D(mean) reduction of 6Gy. Absolute reductions in dose-volume parameters varied from 5% to 11%. Significantly reduced Rwall V30, V40, and A40 were observed with ERB, irrespective of the target volume size.
ERB application significantly reduces Awall and to a lesser degree Rwall doses in high-dose post-prostatectomy IMRT.
Smeenk RJ, van Lin EN, van Kollenburg P, McColl GM, Kunze-Busch M, Kaanders JH. Are you the author?
Reference: Radiother Oncol. 2011 Aug 26. Epub ahead of print.