Pulsed dose rate brachytherapy in head and neck cancers. Feasibility studyof a French cooperative group

Purpose: To prospectively evaluate the feasibility of pulsed dose rate (PDR ) brachytherapy to mimic the continuous low dose rate (cLDR) iridium wire t echnique in head and neck carcinomas. Materials and methods: A series of 30 patients were included from June 1995 to May 1998. The primaries were located in the oral cavity (four T1, seven T2 and two T3), the velotonsillar arch (eight T1 and eight T2) and the pos terior wall tone T3). Thirteen were irradiated by exclusive brachytherapy ( dose, greater than or equal to 45 Gy). The PDR delivered 0.5 Gy/pulse, one pulse/h, day and night, to mimic cLDR irradiation. Results: The implantation was feasible for all the patients, usually easy a nd of good quality. The mean duration/pulse was 13 min, with a mean source activity of 171 mCi. Patient tolerance was poor in nine cases. Sixteen pati ents could receive the whole PDR treatment with a total ranging from 30 to 120 pulses without any problem. Seven had short breakdowns (less than or eq ual to6 h). Seven had definitive breakdowns, but could end the irradiation by manual afterloading of iridium 192 wires. The radioprotection was better (or complete), except for one patient. Most of the breakdowns were related to kinking or flattering of the tube. Conclusions: PDR is feasible in head and neck carcinomas, but necessitates improvement of the quality and control of the plastic tubes. (C) 2001 Elsev ier Science ireland Ltd. All rights reserved.