title: Dosimetric study for cervix carcinoma treatment using intensity modulated radiation therapy (IMRT) compensation based on 3D intracavitary brachytherapy technique.
abstract: OBJECTIVE
  Intensity modulated radiation therapy (IMRT) compensation based on 3D high-dose-rate (HDR) intracavitary brachytherapy (ICBT) boost technique (ICBT + IMRT) has been used in our hospital for advanced cervix carcinoma patients. The purpose of this study was to compare the dosimetric results of the four different boost techniques (the conventional 2D HDR intracavitary brachytherapy [CICBT], 3D optimized HDR intracavitary brachytherapy [OICBT], and IMRT-alone with the applicator in situ).
  
  
  METHODS
  For 30 patients with locally advanced cervical carcinoma, after the completion of external beam radiotherapy (EBRT) for whole pelvic irradiation 45 Gy/25 fractions, five fractions of ICBT + IMRT boost with 6 Gy/fractions for high risk clinical target volume (HRCTV), and 5 Gy/fractions for intermediate risk clinical target volume (IRCTV) were applied. Computed tomography (CT) and magnetic resonance imaging (MRI) scans were acquired using an in situ CT/MRI-compatible applicator. The gross tumor volume (GTV), the high/intermediate-risk clinical target volume (HRCTV/IRCTV), bladder, rectum, and sigmoid were contoured by CT scans.
  
  
  RESULTS
  For ICBT + IMRT plan, values of D90, D100 of HRCTV, D90, D100, and V100 of IRCTV significantly increased (p < 0.05) in comparison to OICBT and CICBT. The D2cc values for bladder, rectum, and sigmoid were significantly lower than that of CICBT and IMRT alone. In all patients, the mean rectum V60 Gy values generated from ICBT + IMRT and OICBT techniques were very similar but for bladder and sigmoid, the V60 Gy values generated from ICBT + IMRT were higher than that of OICBT. For the ICBT + IMRT plan, the standard deviations (SD) of D90 and D2cc were found to be lower than other three treatment plans.
  
  
  CONCLUSIONS
  The ICBT + IMRT technique not only provides good target coverage but also maintains low doses (D2cc) to the OAR. ICBT + IMRT is an optional technique to boost parametrial region or tumor of large size and irregular shape when intracavitary/interstitial brachytherapy cannot be used.
authors: Department of Radiotherapy, Sichuan Cancer Hospital & Institute, Chengdu; Authors contributed equally to this work.
authors: Gang
authors: G
authors: Yin
authors: Department of Radiotherapy, Sichuan Cancer Hospital & Institute, Chengdu; Authors contributed equally to this work.
authors: Pei
authors: P
authors: Wang
authors: Department of Radiotherapy, Sichuan Cancer Hospital & Institute, Chengdu; Authors contributed equally to this work.
authors: Jinyi
authors: J
authors: Lang
authors: Bio-information College, Chongqing University of Posts and Telecommunications, Chongqing; Chongqing Key Laboratory of Photoelectronic Information Sensing and Transmiiting Technology, Chongqing; Chongqing High School Innovation Team of Architecture and Core Technologies of Smart Medical System, Chongqing; Authors contributed equally to this work.
authors: Yin
authors: Y
authors: Tian
authors: Department of Radiotherapy, Sichuan Cancer Hospital & Institute, Chengdu.
authors: Yangkun
authors: Y
authors: Luo
authors: Department of Radiotherapy, Sichuan Cancer Hospital & Institute, Chengdu.
authors: Zixuan
authors: Z
authors: Fan
authors: Faculty of Health Sciences, University of Macau, Taipa, Macau, China.
authors: Kin Yip
authors: KY
authors: Tam
keywords: IMRT; brachytherapy; cervical cancer; cervix carcinoma; dosimetry