HDR intraoperative brachytherapy (IOBT) is applied to locally advanced rectal tumors using a 5 mm thick flexible intraoperative template (FIT). To reduce the procedure time, treatment planning is performed using standard plans that neglect the curvature of the FIT. We have calculated the individual treatment plan, based on the real geometry of the FIT, and the dose at clips placed during surgery. A mean treatment dose of 9.55±0.21Gy was found for the individual plan, compared to the prescribed 10Gy (P<0.0001). The mean central dose was 10.03±0.10Gy in the standard plan and 9.20±0.32Gy in the individual plan (P<0.0001). The mean dose at the corners of the FIT was 10.3Gy in the standard plan and ranged between 10.3 and 10.5Gy in the individual plan. In 63% of the clips, the dose was larger than 15.0Gy, which is equivalent to a gap between the FIT and the target smaller than 5 mm. In 18% of the clips, the dose was smaller than 13.0Gy indicating that locally the gap was larger than 5 mm. Clinical practice will have to prove if these small dose deviations influence the clinical outcome.

Brachytherapy, High dose rate, Rectal cancer, Treatment planning
dx.doi.org/10.1016/j.radonc.2003.10.010, hdl.handle.net/1765/62700
Radiotherapy & Oncology
Department of Radiation Oncology

Kolkman-Deurloo, I.-K.K, Nuyttens, J.J.M.E, Hanssens, P, & Levendag, P.C. (2004). Intraoperative HDR brachytherapy for rectal cancer using a flexible intraoperative template: Standard plans versus individual planning. Radiotherapy & Oncology, 70(1), 75–79. doi:10.1016/j.radonc.2003.10.010