ESTRO 2025 - Abstract Book

S341

Brachytherapy - Physics

ESTRO 2025

for critical organs at risk indicated that VMAT and HDR IRT provided better dose sparing for OARs, even if not statistically significant.

Conclusion: HDR 192Ir IRT provides superior target dose coverage and control over dose distribution, making it highly suitable for complex NMSC cases. VMAT offers a viable alternative with effective OAR sparing, whereas electron therapy may be limited to specific cases with smaller CTVs. This study underscores the importance of personalized planning in radiotherapy and supports the adoption of HDR IRT for targeted NMSC management.

Keywords: brachytherapy, dosimetric comparison, NMSC

References: 1. Kovács, G., & Veen, R. E. (2015). Brachytherapy in the treatment of non-melanoma skin cancer. Journal of Contemporary Brachytherapy , 7(5), 335-343. 2. Kirisits, C., Rivard, M. J., Baltas, D., et al. (2014). Review of clinical brachytherapy uncertainties: TG-186 report by the AAPM and GEC-ESTRO. Medical Physics, 41(7), 071501.

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Digital Poster In vivo measurement of radiation dose during brachytherapy treatment using scintillation detectors Janusz Winiecki 1,2 , Bogna Sobiech 1 , Sandra Witkiewicz-Lukaszek 3 , Yuriy Zorenko 3,1 , Roman Makarewicz 2 1 Medical Physics, Oncology Center, Bydgoszcz, Poland. 2 Department of Oncology and Brachytherapy, Collegium Medicum in Bydgoszcz of Nicholas Copernicus University in Toruń, Bydgoszcz, Poland. 3 Department of Physics, Kazimierz Wielki University, Bydgoszcz, Poland Purpose/Objective: In vivo verification of the dose delivered in brachytherapy remains still an unsolved dosimetric problem. Conventional detectors based on ionization chambers, semiconductors or thermoluminescent materials based on LiF cannot be used for this purpose. The first way to solve the problem is to use dosimetric materials that can be placed in the patient's body to record the delivered radiation dose using the OSL and/or scintillation phenomena. Material/Methods: In this work, it was proposed to use a known scintillation crystal of Ce 3+ doped Ga 3 Ga 3 Al 2 O 12 :Ce garnet (GAGG:Ce) attached with an long optical fiber to measure in situ the radiation dose during brachytherapy treatment. The measurements were first performed in a phantom, and then on patients in the clinical conditions of the Oncology Center in Bydgoszcz. Results: Luminescence spectra from scintillators can be recorded using a long optical fiber and a sensitive spectrometer placed in a safe place. Figure 1 presents a great linear correlation between the dose and signal registered by detector based on the GAGG:Ce crystal (phantom experiments).