An Empirical Model of Carbon-Ion Relative Biological Effectiveness Based on the Linear Correlation Between Radiosensitivity to Photons and Carbon Ions

Authors

David B Flint
Scott J Bright
Conor McFadden
Teruaki Konishi
David K J Martinus
Mandira Manandhar
Mariam Ben Kacem
Lawrence Bronk
Gabriel O Sawakuchi

Publication Date

12-10-2024

Journal

Physics in Medicine & Biology

DOI

10.1088/1361-6560/ad918e

PMID

39530708

PMCID

PMC11632915

PubMedCentral® Full Text Version

Post-print

Abstract

Objective.To develop an empirical model to predict carbon ion (C-ion) relative biological effectiveness (RBE).Approach.We used published cell survival data comprising 360 cell line/energy combinations to characterize the linear energy transfer (LET) dependence of cell radiosensitivity parameters describing the dose required to achieve a given survival level, e.g. 5% (D5%), which are linearly correlated between photon and C-ion radiations. Based on the LET response of the metrics D5%and D37%, we constructed a model containing four free parameters that predicts cells' linear quadratic model (LQM) survival curve parameters for C-ions,αCandβC, from the reference LQM parameters for photons,αXandβX, for a given C-ion LET value. We fit our model's free parameters to the training dataset and assessed its accuracy via leave-one out cross-validation. We further compared our model to the local effect model (LEM) and the microdosimetric kinetic model (MKM) by comparing its predictions against published predictions made with those models for clinically relevant LET values in the range of 23-107 keVμm-1.

Main Results. Our model predicted C-ion RBE within ±7%-15% depending on cell line and dose which was comparable to LEM and MKM for the same conditions.

Significance. Our model offers comparable accuracy to the LEM or MKM but requires fewer input parameters and is less computationally expensive and whose implementation is so simple we provide it coded into a spreadsheet. Thus, our model can serve as a pragmatic alternative to these mechanistic models in cases where cell-specific input parameters cannot be obtained, the models cannot be implemented, or for which their computational efficiency is paramount.

Keywords

Photons, Relative Biological Effectiveness, Carbon, Linear Energy Transfer, Radiation Tolerance, Humans, Models, Biological, Cell Survival, particle therapy, RBE, linear energy transfer, radiosensitivity, modeling, carbon ion

Published Open-Access

yes

Recommended Citation

Flint, David B; Bright, Scott J; McFadden, Conor; et al., "An Empirical Model of Carbon-Ion Relative Biological Effectiveness Based on the Linear Correlation Between Radiosensitivity to Photons and Carbon Ions" (2024). Faculty, Staff and Student Publications. 1598.
https://digitalcommons.library.tmc.edu/uthgsbs_docs/1598