A dosimetric comparison of Xoft Axxent Electronic Brachytherapy and iridium-192 high-dose-rate brachytherapy in the treatment of endometrial cancer

PURPOSE: This analysis was undertaken to dosimetrically compare iridium-192 high-close-rate brachytherapy (IB) and Xoft Axxent Electronic Brachytherapy (XB; Xoft Inc., Sunnyvale, CA) in the treatment of endometrial cancer. METHODS AND MATERIALS: The planning CT scans from 11 patients previously treated with IB were used to construct hypothetical treatment plans using the source characteristics of the XB device. The mean V-95, V-100, and V-150 (percent of the planning target volume that received 95%, 100%, and 150% of the prescription close) were calculated. For both the bladder and rectum, the V-35 (percent of the or-an that received 35% of the prescription close) and V-50 (percent of the organ that received 50% of the prescription dose) were calculated for each patient using both methods of vaginal brachytherapy. RESULTS: The mean %V-95 was 99.7% vs. 99.6% (p = ns ) and the mean %V-100 was 99.0% vs. 99.1% (p = ns) for the IB and XB methods, respectively. The mean %V-150 was 35.8% vs. 58.9% (p < 0.05) for the IB and XB methods, respectively. The mean bladder %V-35 was 47.7% vs. 27.4% (p < 0.05) and the mean bladder %V-50 was 26.5% vs. 15.9% (p < 0.05) for the IB and XB methods, respectively. The mean rectal %V-35 was 48.3% vs. 28.3% (p < 0.05) and the mean rectal %V-50 was 27.8% vs. 17.0% (p < 0.05) for the IB and XB methods, respectively. CONCLUSIONS: The IB and XB methods of vaginal brachytherapy offer equivalent target volume coverage; however, the XB method allows increased sparing of the bladder and rectum. (C) 2008 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.