ESTRO 36 Abstract Book

S967 ESTRO 36 2017 _______________________________________________________________________________________________

3 Hospital of Navarra, Urology, Pamplona, Spain 4 Hospital of Navarra, Surgery, Pamplona, Spain

essential to treatment planning and may be discarded in future. EP-1785 use of rectal tube in vaginal cuff HDR- brachytherapy: an unexpected advantage A. Cerrotta 1 , C. Tenconi 2 , B. Pappalardi 1 , T. Giandini 2 , S. Naimo 1 , D. Mazzeo 2 , E. Mazzarella 2 , S. Grisotto 2 , M. Borroni 2 , C. Fallai 1 , M. Carrara 2 1 Fondazione IRCCS Istituto Nazionale dei Tumori, Department of diagnostic imaging and radiotherapy- Radiotherapy 2, Milan, Italy 2 Fondazione IRCCS Istituto Nazionale dei Tumori, Department of diagnostic imaging and radiotherapy- Medical Physics Unit, Milan, Italy Purpose or Objective Rectal toxicity, both early and late, is a substantial problem in gynecological brachytherapy (BT) , occurring in the majority of patients within the first 2 years after the end of treatment. Specific strategies and efforts are needed to limit high doses to the rectal mucosa without reducing the overall target coverage. The aim of our study, following an occasional observation, is to evaluate if the rectal tube we use in our Institute for in vivo dosimetry allows also a reduction of the rectal dose. Material and Methods In our Institute, adjuvant vaginal BT is always Image Guided (CT/MRI) with a multichannel endovaginal applicator, chosen taking into account both the comfort of the patient and the best contact of the applicator surface with the vaginal mucosa. For all patients, rectal wall in vivo dosimetry is performed with a dedicated rectal tube integrated with dosimeters and rigidly fixed to the endovaginal applicator. Over the time, for technical/ clinical problems, two CT scans (acquired within a time interval of 10 minutes) were obtained in 6 patients : one without and one with rectal tube. Each treatment plan was generated and delivered using CT-scan with rectal tube in order to calculate dose to target and OARs (TPS: Oncentra Brachytherapy System). Vaginal cuff, bladder, rectum and sigmoid were contoured by a single radiation oncologist and the contours were reviewed by all members of the Brachytherapy team. Plan optimization was performed according to International guidelines . Rectum position variation, due to the presence of the rectal tube (diameter: 8.3 mm) , attracted the attention of the team. The treatment plan was transferred on CT scan without rectal tube and OARs and target doses were evaluated. For both plans, bladder and rectum DVHs were assessed considering the near maximum dose to 2cc of each organ, D2cc (%). Results are reported as mean (±SD). The Wilcoxon test for pair samples was used for comparison. Differences were considered statistically significant at p < 0.05. Results No significant variation was found for bladder D2cc with and without rectal tube: (68.7±5.9)% vs (68.7±4.2)%, respectively. D2cc for the rectum systematically increased in all calculated plans without rectal tube: (68.9±5.7)% vs.( 86±6.7)%. Differences were found statistically significant (p=0.031). Conclusion These preliminary results show that an unexpected advantage of the rectal tube, used for in-vivo dosimetry, is the favorable modification of the rectal anatomy with a consequent significant reduction in terms of D2cc. EP-1786 Intraoperative Brachytherapy (HDR-IOBT) in advanced or recurrence gynecologic cancer.. E. Villafranca Iturre 1 , J. Muruzabal 2 , A. Sola 1 , P. Navarrete 1 , M. Barrado 1 , S. Aguirre 2 , S. La Peña 2 , O. Tarrio 2 , J. Jimenez 3 , M. Ciga 4 1 Hospital of Navarra, Radiation Oncology, Pamplona, Spain 2 Hospital of Navarra, Gynaecology, Pamplona, Spain

Purpose or Objective Review our initial results in the treatment with surgery and Intraoperative Brachytherapy (HDR-IOBT) in advanced or recurrence gynecologic cancer. Material and Methods This protocol was designed in 2011 and all cases have been approved in the Committee on Gynecologic Tumors. They included two patient groups: Group 1: patients with advanced cervical cancer with poor response to Radiation and chemotherapy; group 2: patients with pelvic recurrence of gynecological tumors of any origin. In all CT and MRI was performed, in recurrences also PET to exclude metastatic disease. The surgical procedure was pelvic exenteration, enlarged cystectomy or rectal resection or both depending on the extent of disease. After extraction of the surgical specimen, was confirmed in all cases with intraoperative biopsy the absence of macroscopic residual disease. Then, put clips in the surgical bed. Subsequently an applicator Fleipbrup Flap® (Elekta) was placed, with an appropriate number of channels to the extension of the bed. After intraoperative planning, a dose of 10 Gy prescribed at 0.5 cm bed depth was administered. Finally, the applicator was retiring to complete the surgery. Results In the period between October 2011 and September 2016, 22 patients have been included. In group 1, there were 11 patients with cervical cancer stage IIB in 5 p and IIIB in 6; in group 2 were 11 recurrences of 5p cervix, 3p endometrial carcinoma, 2 sarcoma and 1 vulva. With a median follow-up of 22 months (1-61m), the Local DFS 2 years was 67%: Group 1: 73%; Group 2: 44%; 2 years Disease Free Survival 54.7%: Group 1: 65%, Group 2: 32%; 2 years Overall Survical 56%: Group 1: 76%, Group 2: 44%. The complications were fistula: 1 intestinal, 2 bladder , 1osteitis pubis in 1p. stenosis sigma 1p. Conclusion HDR-IOBT associated with pelvic exenteration offers good results of pelvic control and overall survival in patients with gynecologic cancer with a poor prognosis, which usually palliative treatments are offered, although further monitoring is required. However the number of complications, especially fistulas has been important, so we must take it into account for prevention. These results are possible thanks to the multidisciplinary approach to these patients EP-1787 Dosimetric Implications of the organs at risk in Vaginal Cuff Brachytherapy with ML Cylinder N. Dumitru 1 , M. Shojaei 1 , S. Pella 1,2 , T. Leventouri 1 , J. Pinder 1 1 Florida Atlantic University, Medical Physics, Boca Raton, USA 2 21st Century Oncology, Medical Physics, Boca Raton, USA Purpose or Objective To develop a method to evaluate the cumulative dose of organs of risk when using the Multi-Channel Cylindrical Applicators in vaginal cuff brachytherapy. Material and Methods A retrospective analysis of 30 patients treated in 2015 with the Multi-Lumen Cylindrical Applicator with 3 cm diameter, were considered for this study. A total of 150 fractions was received by patients, each of them receiving 5 fractions with 5 Gy each, delivered twice a week and prescribed to the applicator’s surface for 2/3 of the vaginal length. The CT scans of these patients, taken for treatment plan were separately imported into the treatment planning system and paired with the initial CT scan after completing the contouring. Two sets of CT images were fused at a time together with respective to the applicator, using landmark registration. Dosimetric