Abstract
OBJECTIVE: To compare high-dose-rate (HDR) brachytherapy systems with (192)Ir, (60)Co and electronic brachytherapy source (EBS) for treatment of endometrial cancers. METHODS: Two additional plans were generated per patient fraction using a (60)Co source and Xoft-EBS on 10 selected patients, previously treated with a vaginal cylinder applicator using a (192)Ir source. Dose coverage of "PTV_CYLD", a 5-mm shell surrounding the cylinder, was evaluated. Doses to the following organs at risk (OARs) the rectum, bladder and sigmoid were evaluated in terms of V35% and V50%, the percentage volume receiving 35% and 50% of the prescription dose, respectively, and D2cm(3), the highest dose to a 2-cm(3) volume of an OAR. RESULTS: Xoft-EBS reduces doses to all OARs in the lower dose range, but it does not always provide better sparing of the rectum in higher dose range as does evaluation using D2cm3. V150% and V200% for PTV_CYLD was up to four times greater for Xoft-EBS plans than for plans generated with (192)Ir or (60)Co. Surface mucosal (vaginal cylinder surface) doses were also 23% higher for Xoft-EBS than for (192)Ir or (60)Co plans. CONCLUSION: Xoft-EBS is a suitable HDR source for vaginal applicator treatment with advantages of reducing radiation exposure to OARs in the lower dose range, while simultaneously increasing the vaginal mucosal dose. ADVANCES IN KNOWLEDGE: This work presents newer knowledge in dosimetric comparison between (192)Ir or (60)Co and Xoft-EBS sources for endometrial vaginal cylinder HDR planning.