title: Evaluating adjacent organ radiation doses from postoperative intracavitary vaginal vault brachytherapy for endometrial cancer.
abstract: OBJECTIVE
  To document doses received by critical organs during adjuvant high-dose-rate (HDR) vaginal vault brachytherapy.
  
  
  METHODS
  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.
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; University of British Columbia, Vancouver, Canada. Electronic address: jcaon-02@bccancer.bc.ca.
authors.forename: Julianna
authors.initials: J
authors.lastname: Caon
authors.affiliation: University of British Columbia, Vancouver, Canada; Vancouver Island Centres, Vancouver, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Holloway
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; Department of Medical Physics, BC Cancer Agency, Vancouver, Canada.
authors.forename: Rustom
authors.initials: R
authors.lastname: Dubash
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; Department of Medical Physics, BC Cancer Agency, Vancouver, Canada.
authors.forename: Conrad
authors.initials: C
authors.lastname: Yuen
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada; University of British Columbia, Vancouver, Canada.
authors.forename: Christina
authors.initials: C
authors.lastname: Aquino-Parsons
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D012809:Colon, Sigmoid / Q000528:radiation effects; D016889:Endometrial Neoplasms / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects*; D011184:Postoperative Period; D011829:Radiation Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods; D012007:Rectum / Q000528:radiation effects; D012189:Retrospective Studies; D001743:Urinary Bladder / Q000528:radiation effects; D014621:Vagina / Q000528:radiation effects
keywords: Brachytherapy; Dosimetry; Endometrial cancer; Vaginal vault