Julianna Caon1, Caroline Holloway2, Rustom Dubash3, Conrad Yuen3, Christina Aquino-Parsons4. 1. Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; University of British Columbia, Vancouver, Canada. Electronic address: jcaon-02@bccancer.bc.ca. 2. University of British Columbia, Vancouver, Canada; Vancouver Island Centres, Vancouver, Canada. 3. Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; Department of Medical Physics, BC Cancer Agency, Vancouver, Canada. 4. Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; University of British Columbia, Vancouver, Canada.
Abstract
PURPOSE: To document doses received by critical organs during adjuvant high-dose-rate (HDR) vaginal vault brachytherapy. METHODS AND MATERIALS: Patients treated with HDR vaginal vault radiation between January 1, 2009, and January 31, 2012, who had a CT simulation with the treatment cylinder in situ were included. The CT scans were retrospectively reviewed and the rectum, sigmoid, small bowel, and bladder were contoured. Standardized plans treating the upper 4 cm of the vaginal vault were used to deliver a total of 21 Gy (Gy) at 0.5 cm from the apex of the vaginal vault in three fractions. RESULTS: There were 41 patients. Median age was 62 years. The median vaginal cylinder diameter was 3 cm. The mean 2cc dose to the rectum, sigmoid, small bowel, and bladder were 5.7, 4.7, 4.0, and 5.6 Gy, respectively. Bladder volume ranged from 67-797cc. Assuming minimal interfraction organ variation, the equivalent dose in 2 Gy/fraction was extrapolated from data and may be near or beyond organ tolerance for rectum, sigmoid, and small bowel in some cases. Spearman correlation found that increased bladder volume was not associated with adjacent organs at risk dose but may be associated with a trend (p=0.06) toward increased bladder dose (R=0.30). CONCLUSIONS: This study describes the dose received by adjacent critical structures during vaginal vault HDR brachytherapy. This is important information for documentation in the rare setting of treatment-related toxicity or recurrence. Bladder volume was not associated with dose to adjacent organs. Crown
PURPOSE: To document doses received by critical organs during adjuvant high-dose-rate (HDR) vaginal vault brachytherapy. METHODS AND MATERIALS: Patients treated with HDR vaginal vault radiation between January 1, 2009, and January 31, 2012, who had a CT simulation with the treatment cylinder in situ were included. The CT scans were retrospectively reviewed and the rectum, sigmoid, small bowel, and bladder were contoured. Standardized plans treating the upper 4 cm of the vaginal vault were used to deliver a total of 21 Gy (Gy) at 0.5 cm from the apex of the vaginal vault in three fractions. RESULTS: There were 41 patients. Median age was 62 years. The median vaginal cylinder diameter was 3 cm. The mean 2cc dose to the rectum, sigmoid, small bowel, and bladder were 5.7, 4.7, 4.0, and 5.6 Gy, respectively. Bladder volume ranged from 67-797cc. Assuming minimal interfraction organ variation, the equivalent dose in 2 Gy/fraction was extrapolated from data and may be near or beyond organ tolerance for rectum, sigmoid, and small bowel in some cases. Spearman correlation found that increased bladder volume was not associated with adjacent organs at risk dose but may be associated with a trend (p=0.06) toward increased bladder dose (R=0.30). CONCLUSIONS: This study describes the dose received by adjacent critical structures during vaginal vault HDR brachytherapy. This is important information for documentation in the rare setting of treatment-related toxicity or recurrence. Bladder volume was not associated with dose to adjacent organs. Crown
Authors: María Del Carmen Salas Buzón; Lucía Gutiérrez Bayard; Raquel Rodríguez Sanchez; Luis Ángel Quiñones Rodríguez; Sarah Sayago Gil; Cristina Muñoz Higueras Journal: J Contemp Brachytherapy Date: 2021-12-30