https://doi.org/10.1140/epjp/s13360-024-05148-5
Regular Article
Monte Carlo-based evaluation of the relevant RBE values to produced low-energy X-rays by INTRABEAM and Axxent dedicated IORT facilities
Physics Department, Hakim Sabzevari University, P. O. 9617976487, Daneshgah Blvd, Sabzevar, Iran
b h.baghani@hsu.ac.ir, hamidreza.baghani@gmail.com
Received:
3
June
2022
Accepted:
2
April
2024
Published online:
18
April
2024
Intraoperative radiotherapy (IORT) by low-energy X-rays is a single-fraction modality for tumor bed irradiation following surgery. Two specific machines, including INTRABEAM and Axxent, are available for this purpose. Current study aims to compare the RBE values relevant to produced X-rays by these machines using a hybrid Monte Carlo (MC) simulation approach. Validated MC models of INTRABEAM and Axxent machines with nominal energies of 40 and 50 kV, simulated by GEANT4 toolkit, were employed for RBE assessments. Scored X-ray spectra for each studied machine were used to calculate the corresponding secondary electron spectra at various depths and nominal energies inside the water. Then, Monte Carlo damage simulation (MCDS) code was employed to calculate the initial DNA damages (single and double-strand breaks (SSB and DSB)) and relevant RBE values. Results showed that the scored X-ray spectra for Axxent and INTRABEAM machines are different, a fact which can affect the RBE values for these machines. RBESSB values for Axxent machine were higher than those of INTRABEAM up to 1.4%. In return, RBEDSB values for INTRABEAM machine were greater than Axxent ones up to 4.1%. The obtained RBE values for both machines had a strong and weak dependency on depth and energy, respectively. It can be concluded that the RBE values for studied IORT machines would be different at the same clinical conditions, an issue which can influence the prescribed dose according to the type of employed IORT machine.
Key words: Intraoperative radiotherapy / Low-energy X-rays / Axxent machine / INTRABEAM machine / Relative biological effectiveness / Hybrid Monte Carlo simulation
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
