S1624
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
compromise affecting human health.Research is ongoing to characterise this compromise across dose levels and dose rates including FLASH, different bacterial strains and different tests, including bile acid metabolism assays, RNA gel electrophoresis and microscopy. Understanding the radiosensitivity of microbiome strains and functions important to health can inform radiotherapy strategies and development of countermeasures to improve health outcomes for patients and astronauts. References: [1] N. Iida et al., “Commensal bacteria control cancer response to therapy by modulating the tumor microenvironment,” Science, vol. 342, no. 6161, pp. 967–970, Nov. 2013.[2] A. Mitra et al., “Microbial Diversity and Composition is Associated with Patient- Reported Toxicity during Chemoradiation Therapy for Cervical Cancer,” Int. J. Radiat. Oncol. Biol. Phys., vol. 107, no. 1, pp. 163–171, May 2020.[3] C. Manichanh et al., “The Gut Microbiota Predispose to the Pathophysiology of Acute Postradiotherapy Diarrhea,” Off. J. Am. Coll. Gastroenterol. ACG, vol. 103, no. 7, p. 1754, Jul. 2008.[4] E. Gonzalez et al., “Spaceflight alters host-gut microbiota interactions,” Npj Biofilms Microbiomes, vol. 10, no. 1, p. 71, Aug. 2024. Keywords: gut microbiome, radiotherapy, astronaut health Mini-Oral 127 Towards real-time 2D dosimetry for QA and in vivo applications in ultra-high dose rate FLASH radiotherapy using silicon carbide detector technology Sophie Heinrich 1 , Ivan Lopez-Paz 2 , Celeste Fleta 2 , Angela M. Henao 2 , Araceli Gago ‑ Arias 3 , Raul Yanez 4 , Faustino Gomez 4 , Consuelo Guardiola 2 1 U1021/UMR3347, Institut Curie, Orsay, France. 2 Department of Micro & Nano Systems, Institute of Microelectronics of Barcelona (IMB-CNM, CSIC), Barcelona, Spain. 3 Group of Medical Physics and Biomathematics, Instituto de Investigación Sanitaria de Santiago, Santiago de Compostela, Spain. 4 Department of Particle Physics, University of Santiago de Compostela, Santiago de Compostela, Spain Purpose/Objective: The clinical translation of FLASH radiotherapy relies on the availability of robust dosimetry systems capable of accurate, real-time monitoring under ultra-high dose rate (UHDR) conditions. While point detectors such as the FlashDiamond (PTW) have been designed for reference measurements, no system currently enables real-time 2D mapping of UHDR dose distributions — a critical need for quality assurance (QA) and in vivo verification, both in preclinical and clinical settings.
This project aims at the development and evaluation of a 2D detector matrix based on silicon carbide (SiC), a material combining fast response, radiation hardness, and dose-rate independence [1], as a new platform for preclinical FLASH dosimetry with potential for clinical adaptation. Material/Methods: Ultra-thin SiC diodes (600 µm diameter, 3 µm active layer, 3.2 g/cm³ density) developed by the Institute of Microelectronics of Barcelona (IMB-CNM) were characterized under pulsed UHDR electron beams. The response linearity, dose-per-pulse (DPP) dependence, and temporal resolution were evaluated on a dedicated preclinical electron LINAC with FLASH capabilities. A prototype 4×4 detector array was fabricated and mounted on a motorized micrometric translation stage for 2D dose mapping of a 40 mm- diameter beam. In parallel, preliminary prototypes mounted on flexible circuits were fabricated to assess their robustness and suitability for localized in vivo dosimetry in animal models. Results: Individual SiC detectors exhibited linear DPP response up to at least 12 Gy/pulse (≈1000 Gy/s), stable signal response over multiple pulses, and sufficient temporal resolution to resolve individual pulse widths. The 4×4 prototype array accurately reproduced the 2D dose distribution measured by radiochromic films, demonstrating spatial uniformity and stability under UHDR conditions. Flexible assemblies showed promising performance while adapting to curved geometries, supporting their use for real-time dose monitoring in small-animal irradiations. Conclusion: This study establishes the basis of a fast, precise, and adaptable 2D dosimetry platform dedicated to UHDR pulsed beams. The SiC detector technology shows strong potential for integration into preclinical FLASH experiments, improving dose control and experimental reproducibility, and represents a key step toward clinically translatable real-time in vivo dosimetry systems for FLASH radiotherapy.This study was funded by the LaCaixa Health foundation DosiFLASH Project (HR23-00718). References: [1] Fleta et al 2024 Phys. Med. Biol. 69 095013 Keywords: FLASH radiotherapy, 2D detector, silicone carbide, Digital Poster 222 Comparison between measurements and Monte Carlo models for LIAC HWL intraoperative radiotherapy equipment.
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