PURPOSE: Vaginal cylinder high-dose-rate (HDR) brachytherapy is currently one of the most common procedures performed in the treatment of early-stage endometrial cancer. However, current recommendations by the American Brachytherapy Society regarding fractional re-imaging and dose calculation for organs at risk for HDR vaginal cuff brachytherapy are not well defined. In this study, we aim to compare a fractional re-imaging approach using computed tomographic (CT) scans prior to each fraction with a first fraction imaging-only approach with respect to bladder, rectal, and bowel dosimetry. METHODS AND MATERIALS: Nineteen endometrial cancer patients undergoing vaginal cuff brachytherapy for endometrial cancer were imaged with CT scanning prior to every HDR fraction (fractional re-imaging [FRI]). Dose to the bowel, bladder, and rectum were calculated and compared with the estimated dose if imaging and planning were done only on the first fraction (first fraction imaging [FFI]). RESULTS: In the analysis of FFI versus FRI, we observed mean bladder doses of 8.34 Gy vs 8.33 Gy (P = .98), mean rectal doses of 12.19 Gy versus 12.14 Gy (P = .81), and mean bowel doses of 2.82 Gy versus 2.76 Gy (P = .81). The FFI approach underestimated the FRI doses to the bladder, rectum, and bowel by 20% or more in 11%, 5%, and 29% of patients, respectively. Cost analysis revealed an estimated $663.06, or a 35% savings per patient treated with FFI. CONCLUSIONS: There is no statistically significant difference in the mean dose to the bladder, rectum, or bowel in patients undergoing HDR vaginal cuff brachytherapy with a first fraction imaging scheme versus a fractional re-imaging scheme. These results indicate that fractional re-imaging is not necessary except in patients whose estimated dose to critical organs is near the maximum limit.
PURPOSE: Vaginal cylinder high-dose-rate (HDR) brachytherapy is currently one of the most common procedures performed in the treatment of early-stage endometrial cancer. However, current recommendations by the American Brachytherapy Society regarding fractional re-imaging and dose calculation for organs at risk for HDR vaginal cuff brachytherapy are not well defined. In this study, we aim to compare a fractional re-imaging approach using computed tomographic (CT) scans prior to each fraction with a first fraction imaging-only approach with respect to bladder, rectal, and bowel dosimetry. METHODS AND MATERIALS: Nineteen endometrial cancerpatients undergoing vaginal cuff brachytherapy for endometrial cancer were imaged with CT scanning prior to every HDR fraction (fractional re-imaging [FRI]). Dose to the bowel, bladder, and rectum were calculated and compared with the estimated dose if imaging and planning were done only on the first fraction (first fraction imaging [FFI]). RESULTS: In the analysis of FFI versus FRI, we observed mean bladder doses of 8.34 Gy vs 8.33 Gy (P = .98), mean rectal doses of 12.19 Gy versus 12.14 Gy (P = .81), and mean bowel doses of 2.82 Gy versus 2.76 Gy (P = .81). The FFI approach underestimated the FRI doses to the bladder, rectum, and bowel by 20% or more in 11%, 5%, and 29% of patients, respectively. Cost analysis revealed an estimated $663.06, or a 35% savings per patient treated with FFI. CONCLUSIONS: There is no statistically significant difference in the mean dose to the bladder, rectum, or bowel in patients undergoing HDR vaginal cuff brachytherapy with a first fraction imaging scheme versus a fractional re-imaging scheme. These results indicate that fractional re-imaging is not necessary except in patients whose estimated dose to critical organs is near the maximum limit.
Authors: Matthew M Harkenrider; Alec M Block; Kaled M Alektiar; David K Gaffney; Ellen Jones; Ann Klopp; Akila N Viswanathan; William Small Journal: Brachytherapy Date: 2016-05-31 Impact factor: 2.362