ESTRO 2025 - Abstract Book

S319

Brachytherapy - Physics

ESTRO 2025

Conclusion: The calibration of the MicroDiamond detector and application of geometric correction factors from the clinical electron beam seems to provide an independent method to perform QA for Ru-106 applicators in hospital environment.

Keywords: Ru-106, electron beam, dosimetry

References: 1. ICRU Report 72 Dosimetry of Beta Rays and Low-Energy Photons for Brachytherapy with Sealed Sources. International Commission on Radiation Units and Measurements 4: 2004 2. Technical Reports Series No. 492 Dosimetry in brachytherapy – an international code of practice for secondary standards dosimetry laboratories and hospitals. International Atomic Energy Agency: 2023 3. Vynckier S. and Wambersie A. Dosimetry of beta sources in radiotherapy I. The beta point source dose function. Phys. Med. Biol. 1982;27: 1339-1347. doi: 10.1088/0031–9155/27/11/004.

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Digital Poster a mixed reality-guided intraoperative visual support system for combined intracavitary and interstitial brachytherapy for cervical cancer Ryuta Hirai Radiation Oncology, Saitama medical university International medical center, Saitama, Japan Purpose/Objective: We developed and prototyped a mixed reality (MR)-guided intraoperative visual support system for inserting interstitial needle applicators for cervical cancer. Material/Methods: HoloLens2 was chosen as a head-mounted display (HMD), and the Unity game development engine and Microsoft MR Tool Kit were used for the development of an MR application. A schematic of the merging worlds is shown in Figure 1. A QR code (QR) was generated and printed as a position alignment reference when merging the real and virtual worlds. An anthropomorphic RANDO phantom (phantom) was used in this study (Fig. 2). The phantom was positioned near the QR, and CT scanning was performed. As with CT imaging, the phantom was set up to acquire MRI images. Brachytherapy treatment planning was performed using the Oncentra Brachy ® treatment planning system for the CT and MRI images acquired with the phantom, and treatment plan data were stored as DICOM-RT structure and dose files. The acquired CT and MRI images and treatment planning data were converted from DICOM to an object file (OBJ) which is a data format that represents 3D shapes. These OBJ data were imported into the virtual world built on Unity software. The visual studio solution file (SLN) was generated by 3D models imported into the virtual space constructed on Unity. The SLN was sent from Unity to Visual Studio to build an MR application for intraoperative visual support, and the MR application was sent to the HMD via Wi-Fi and ran.