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Author Moskvin, V. ♦ Tsiamas, P. ♦ Axente, M. ♦ Farr, J. ♦ Stewart, R.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION, THERMAL, AND OTHER ENVIRONMENTAL POLLUTANT EFFECTS ON LIVING ORGANISMS AND BIOLOGICAL MATERIALS ♦ RADIATION PROTECTION AND DOSIMETRY ♦ AEROBIC CONDITIONS ♦ BRAGG CURVE ♦ DNA ♦ HEAVY IONS ♦ IRRADIATION ♦ MONTE CARLO METHOD ♦ NEOPLASMS ♦ PROTON BEAMS ♦ RADIATION DOSES ♦ RADIOTHERAPY ♦ RBE ♦ SIMULATION ♦ STRAND BREAKS
Abstract Purpose: One of the more critical initiating events for reproductive cell death is the creation of a DNA double strand break (DSB). In this study, we present a computationally efficient way to determine spatial variations in the relative biological effectiveness (RBE) of proton therapy beams within the FLUKA Monte Carlo (MC) code. Methods: We used the independently tested Monte Carlo Damage Simulation (MCDS) developed by Stewart and colleagues (Radiat. Res. 176, 587–602 2011) to estimate the RBE for DSB induction of monoenergetic protons, tritium, deuterium, hellium-3, hellium-4 ions and delta-electrons. The dose-weighted (RBE) coefficients were incorporated into FLUKA to determine the equivalent {sup 6}°60Co γ-ray dose for representative proton beams incident on cells in an aerobic and anoxic environment. Results: We found that the proton beam RBE for DSB induction at the tip of the Bragg peak, including primary and secondary particles, is close to 1.2. Furthermore, the RBE increases laterally to the beam axis at the area of Bragg peak. At the distal edge, the RBE is in the range from 1.3–1.4 for cells irradiated under aerobic conditions and may be as large as 1.5–1.8 for cells irradiated under anoxic conditions. Across the plateau region, the recorded RBE for DSB induction is 1.02 for aerobic cells and 1.05 for cells irradiated under anoxic conditions. The contribution to total effective dose from secondary heavy ions decreases with depth and is higher at shallow depths (e.g., at the surface of the skin). Conclusion: Multiscale simulation of the RBE for DSB induction provides useful insights into spatial variations in proton RBE within pristine Bragg peaks. This methodology is potentially useful for the biological optimization of proton therapy for the treatment of cancer. The study highlights the need to incorporate spatial variations in proton RBE into proton therapy treatment plans.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-06-15
Publisher Place United States
Journal Medical Physics
Volume Number 42
Issue Number 6


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