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Sci—Sat AM: Brachy — 06: Monte carlo DNA damage simulations of kV cbct radiation
Author(s) -
Kirkby C,
Ghasroddashti E,
Poirier Y,
Tambasco M,
Stewart RD
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4740213
Subject(s) - monte carlo method , relative biological effectiveness , context (archaeology) , nuclear medicine , physics , dosimetry , radiation treatment planning , radiation , effective dose (radiation) , radiation therapy , computational physics , medical physics , medicine , optics , mathematics , radiology , statistics , biology , paleontology
When performed daily, cone beam CT (CBCT) images can accumulate radiation dose to non‐negligible levels. Because kV x‐rays have a larger relative biological effectiveness (RBE) than its MV x‐rays, the accumulated absorbed dose needs to be multiplied by an appropriate RBE to better evaluate the impact of CBCT dose in a treatment planning context. We investigated this question using PENLEOPE simulations to look in detail at the electron energy spectra produced by kV x‐rays and Co‐60 γ‐rays in biologically motivated geometries. The electron spectra were input into the published Monte Carlo Damage Simulation (MCDS) and used to estimate the average number of double strand breaks (DSBs) per Gy per cell. Our results suggest an approximately 10% increase in the RBE for DSB induction. For the majority of treatment planning scenarios where imaging dose is only a small fraction of the total delivered dose to target volumes and organs at risk, the increase in RBE is not critical to be factored in, however for it may play a significant role in predicting the induction of secondary cancers.