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Dosimetric assessment of photon, proton, and carbon ion beams in a magnetic field; a Monte Carlo simulation study
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S. Bagherzadeh   , H. Rajabi |
| Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran , hrajabi@modares.ac.ir |
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Abstract: (20 Views) |
Background: The advent of Magnetic Resonance-guided (MR-guided) radiotherapy, facilitated by MR-guided linear accelerators (MR-LINACs), has significantly enhanced the availability of online adaptive radiotherapy treatments. Research indicates that a static magnetic field influences the amount of radiation absorbed by patients undergoing MR-guided radiotherapy. This study employed Monte Carlo simulations to assess the dose distribution of Photon, Proton, and Carbon ion beams in the absence and presence of magnetic fields. Materials and Methods: All simulations were performed using version 9.1 of the GATE software. The experimental configuration consisted of a water phantom equipped with a one mm-thick air slit oriented parallel to the x-y plane. Energy and dose measurements from both the primary beam and secondary electrons were conducted using DoseActor. Results: The observed magnetic field shifted the Bragg peak for both proton and carbon ion beams, with an increasing displacement correlating to higher primary beam energy levels. Furthermore, there was a positive correlation between secondary electron doses and magnetic field intensity; in scenarios involving a 7 Tesla magnetic field, photon doses at the water-air interface increased considerably. Additionally, at the air slit location, doses from photon-induced secondary electrons markedly increased at this interface. Conclusion: The Electron Return Effect (ERE) influences dose distribution at water-air boundaries. Increased initial energies and more robust magnetic fields exacerbate these phenomena, emphasizing the critical importance of rigorous deliberation in the treatment planning process. |
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| Keywords: Comprehensive Magnetic Fields, Carbon-Ion Therapy, Monte Carlo Method, Proton Therapy, Protons. |
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Full-Text [PDF 808 kb]
(2 Downloads)
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Type of Study: Original Research |
Subject:
Radiation Biology
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