title: Optimum organ volume ranges for organs at risk dose in cervical cancer intracavitary brachytherapy.
abstract: OBJECTIVE
  To analyze the optimum organ filling point for organs at risk (OARs) dose in cervical cancer high-dose-rate (HDR) brachytherapy.
  
  
  METHODS
  In a retrospective study, 32 locally advanced cervical cancer patients (97 insertions) who were treated with 3D conformal external beam radiation therapy (EBRT) and concurrent chemotherapy during 2010-2013 were included. Rotterdam HDR tandem-ovoid applicators were used and computed tomography (CT) scanning was performed after each insertion. The OARs delineation and GEC-ESTRO-based clinical target volumes (CTVs) contouring was followed by 3D forward planning. Then, dose volume histogram (DVH) parameters of organs were recorded and patients were classified based on their OARs volumes, as well as their inserted tandem length.
  
  
  RESULTS
  The absorbed dose to point A ranged between 6.5-7.5 Gy. D0.1cm(3) and D2cm(3) of the bladder significantly increased with the bladder volume enlargement (p value < 0.05). By increasing the bladder volume up to about 140 cm(3), the rectum dose was also increased. For the cases with bladder volumes higher than 140 cm(3), the rectum dose decreased. For bladder volumes lower than 75 cm(3), the sigmoid dose decreased; however, for bladder volumes higher than 75 cm(3), the sigmoid dose increased. The D2cm(3) of the bladder and rectum were higher for longer tandems than for shorter ones, respectively. The divergence of the obtained results for different tandem lengths became wider by the extension of the bladder volume. The rectum and sigmoid volume had a direct impact on increasing their D0.1cm(3) and D2cm(3) , as well as decreasing their D10, D30, and D50.
  
  
  CONCLUSIONS
  There is a relationship between the volumes of OARs and their received doses. Selecting a bladder with a volume of about 70 cm(3) or less proved to be better with regards to the dose to the bladder, rectum, and sigmoid.
authors.affiliation: Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Islamic Republic of Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Siavashpour
authors.affiliation: Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Islamic Republic of Iran.
authors.forename: Mahmoud Reza
authors.initials: MR
authors.lastname: Aghamiri
authors.affiliation: Department of Radiotherapy, Cancer Institute, Tehran University of Medical Science, Tehran, Islamic Republic of Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Jaberi
authors.affiliation: Department of Radiotherapy, Hafte Tir Hospital, Tehran, Islamic Republic of Iran.
authors.forename: Hamid Reza Dehghan
authors.initials: HR
authors.lastname: Manshadi
authors.affiliation: Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Islamic Republic of Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Ghaderi
authors.affiliation: Department of Radiotherapy and Oncology, Comprehensive Cancer Center, Medical University of Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Kirisits
keywords: OARs; bladder volume; brachytherapy; cervical cancer