ESTRO 2023 - Abstract Book

S1962

Digital Posters

ESTRO 2023

Conclusion New type of RING applicators was offered for clinical use and measured errors of dwell positions compare with system template were significant. Study suggestion is to create more complex but also more accurate error correction, which includes separate error correction for each applicator’s each dwell position. With a particular focus on re-checks corrected template after replacing the source for all clinically used applicators, giving particular attention to 90 ⁰ applicators, showed errors that are outside acceptable range. PO-2178 Development of an inclined applicator for intraoperative radiotherapy 1 Yonsei Cancer Center, Yonsei University College of Medicine , Department of Radiation Oncology, Seoul, Korea Republic of; 2 School of Medicine, Ewha Womans University, Ewha Medical Research Institute, Seoul, Korea Republic of; 3 Yongin Severance Hospital, Yonsei University College of Medicine, Department of Radiation Oncology, Yongin, Korea Republic of; 4 Yonsei Cancer Center, Yonsei University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of; 5 Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of Purpose or Objective In this study, we developed an inclined applicator to shield normal tissue and increase indications during intraoperative radiation therapy (IORT). The development conditions of the applicator are as follows: 1) beam flatness, 2) shield radiation in areas other than the target window, and 3) enable treatment in various directions. The basic dosimetric evaluations for clinical application were performed. Materials and Methods The IORT equipment used in this study is an INTRABEAM system emitting up to 50 kV X-ray. We designed and made inclined applicators with 3d printer for 0 and 45 degrees, respectively. Each applicator was designed to generate a flat and an un flat beam and to shield leakage dose in the unnecessary area with Cerrobend. The uniformity in profile, percentage depth dose, leakage, and dose rate of the beam were measured with EBT3 film and OSLD. Results As a result of the uniformity of developed applicators at depths of 0, 2, 5, and 15 mm are as follows: 1.23, 1.28, 1.30, and 1.22 for a flat beam, and 1.29, 1.32, 1.27 and 1.25 for an un-flat beam, respectively. As a result of leakage measurement, no dose was measured for the distance after 1 mm from the surface. For the results of dose rate, when irradiated for 3 minutes, the flat beam and un-flat beam of the 0 degree applicator were 51.0 and 52.9 cGy, respectively, and the 45 degree applicator was 48.5 and 54.8 cGy, respectively. Conclusion We demonstrated that the developed applicator has a uniform beam, good shielding, and minimizes radiation exposure to normal tissue by enabling irradiation from various directions. In conclusion, clinical application of customized applicator will facilitate IORT treatment in the chest and abdomen with high critical organs. Dose calibration has been completed and preparations are being made for clinical application. J.H. Kim 1 , S.H. Ahn 2 , K.W. Park 3 , I.J. Lee 4 , J.S. Kim 5

PO-2179 Temperature effect on optical fibre sensors for in-vivo dosimetry in HDR brachytherapy

O. Mc Laughlin 1 , S. Esteve 2 , O. Houlihan 1,3 , G. Workman 2 , M. Byrne 2 , S. Jain 1,3 , A. Hounsell 2,1 , K. Prise 1 , C. McGarry 1,2

1 Queen's University Belfast, Patrick G Johnston Centre for Cancer Research, Belfast, United Kingdom; 2 Belfast Health and Social Care Trust, Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast, United Kingdom; 3 Belfast Health and Social Care Trust, Department of Clinical Oncology, Northern Ireland Cancer Centre, Belfast, United Kingdom

Purpose or Objective