ESTRO 2023 - Abstract Book

S1925

Digital Posters

ESTRO 2023

1. 3D applicator with needles in Oncentra planning system

2. Fletcher applicator with 3D add-on and needles

Results Biomed Clear Resin was used in the production of monoovoid, which is biocompatible and suitable for invasive procedures.

The maximum difference between the dimensions of the 3D model and the 3D printed addition is 0.4 ± 0.05 mm and 0.1°.

The stability of the material was checked in the STERRAD sterilization system operating on hydrogen peroxide. The largest volume reduction was 0.2 mm.

For dose distribution DTA/DD (distance to agreement/dose difference) 2mm/5% criteria and the passing percentage of 90% were used. Two- and three-dimensional dose distribution analyzes showed accuracies of 98.5% and 94.7% respectively. The experiment showed that the planned and real needle locations coincided, with differences in simulated dose distributions ranging from 1.5 to 5.3%. Based on a specific clinical case, 3D add-on could increase the overlap of the target volume with the treatment dose by 18%. Conclusion 3D printing makes it possible to adjust the size and shape of the individual treatment applicator and the angles of the interstitial needles to achieve a better dose distribution, i.e. to improve the quality of treatment. 1 Hospital clinic of Barcelona , Radiation Oncology Unit, Barcelona, Spain; 2 University of Barcelona, Fonaments clinics Department, Barcelona, Spain; 3 Henan provincial people’s hospital , cancer center, Zhengzhou, China; 4 Hospital clinic of Barcelona, Radiation Oncology Unit, Barcelona, Spain; 5 Hospital clinic of barcelona, Radiation oncology Unit, Barcelona, Spain; 6 Hospital Clinic of Barcelona, Gynecological Cancer Unit, Barcelona, Spain; 7 Hospital clinic of Barcelona, Gynecological Cancer Unit, Barcelona, Spain Purpose or Objective To compare two vaginal brachytherapy (VBT) fractionation schedules in postoperative endometrial carcinoma (PEC) patients considering vaginal-cuff control, late toxicities (vagina, rectum, and bladder), EQD2(a/b=3) received in the most exposed 2cm3 to dose in clinical target volume (CTV) and vaginal dilator use. Materials and Methods 110 PEC patients were treated with two VBT schedules from 2011 to 2021. The 110 patients fulfilled the inclusion criteria for exclusive brachytherapy and were analyzed in two groups: Group-1 included 44 patients treated with 3 fractions of 6 Gy from September 2011 to April 2014 and Group-2 included 66 patients treated with 2 fractions of 7.5 Gy from July 2015 to November 2021. The dose was prescribed at 5mm from the applicator surface with an active length of 2.5cm. CTV was delineated in all the patients and the EQD2(a/b=3) received in the most exposed 2cm3 to dose in CTV was calculated. Late toxicity was prospectively assessed using RTOG scores for bladder and rectum, and the LENT-SOMA objective criteria for vagina. Statistics: Descriptive analysis, Chi-square and Student’s t tests. PO-2140 Are 7.5Gyx2 fractions more efficient than 6Gyx3 in postoperative endometrial cancer brachytherapy? F. Noorian 1,2 , R. Abellana 2 , Y. Zhang 3 , A. Herreros 2,4 , J. Rochera 5 , C. Baltrons 4 , G. Antelo 4 , A. Torne 6 , A. Rovirosa 4,2,7

Results