ESTRO 36 Abstract Book

S981 ESTRO 36 _______________________________________________________________________________________________

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 evaluations were performed. The maximum doses received by the rectum wall, bladder wall, bowels and PTV were analyzed and traced over the five fractions to determine the total dose distribution over the entire prescribed treatment. Results No contour of any of the OAR was exactly similar when CT images were fused to each other. Depending on the depth of the insertion the PTV varied minimally. Each plan was performed independently and cumulated 2 at a time until all 5 fractions were added to the initial fraction. There is a difference between the doses received by the OARs between treatments and between the points of maximum does. The PTV volumes vary from fraction to fraction. The maximum dose varied between 12% and 27% in rectum wall and bladder wall. The minimum dose varied between 2% and 7% in rectum wall and bladder wall. The average dose varied between 9% and 21% in rectum wall and bladder wall. The cumulative treatment does do not indicate a total maximum dose exceeding the tolerances for the rectum and bladder. Conclusion The variation in volumes of OARs and isodoses near the OARs, indicate that the estimated doses to OARs on the planning system may not be the same dose delivered to the patient in all the fractions. There are no major differences between the prescribed dose and the delivered dose over the total number of fractions. Variation in the length of the cylinder part implanted into the vagina and PTV's coverage indicates an inconsistency in the entire vaginal cuff in all five fractions. In some cases, the critical organs will benefit if the consecutive plans will be made after the CT scans are registered with the initial. All the cases studied indicate the need for more detailed study in order to establish a protocol of planning.

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