Investigating the Implications of a Variable RBE on Proton Dose Fractionation Across a Clinical Pencil Beam Scanned Spread-Out Bragg Peak

0459898 - ÚJF 2017 RIV US eng J - Journal Article
Marshall, T. I. - Chaudhary, P. - Jelínek Michaelidesová, Anna - Vachelová, Jana - Davídková, Marie - Vondráček, V. - Schettino, G. - Prise, K. M.
Investigating the Implications of a Variable RBE on Proton Dose Fractionation Across a Clinical Pencil Beam Scanned Spread-Out Bragg Peak.
International Journal of Radiation Oncology Biology Physics. Roč. 95, č. 1 (2016), s. 70-77. ISSN 0360-3016. E-ISSN 1879-355X
Institutional support: RVO:61389005
Keywords : proton therapy * irradiation * cells
Subject RIV: BO - Biophysics
Impact factor: 5.133, year: 2016

o investigate the clinical implications of a variable relative biological effectiveness (RBE) on proton dose fractionation. Using acute exposures, the current clinical adoption of a generic, constant cell killing RBE has been shown to underestimate the effect of the sharp increase in linear energy transfer (LET) in the distal regions of the spread-out Bragg peak (SOBP). However, experimental data for the impact of dose fractionation in such scenarios are still limited. Significant variations in the cell killingRBE for fractionated exposures along the proton dose profile were observed. RBE increased sharply toward the distal position, corresponding to a reduction in cell sparing effectiveness of fractionated proton exposures at higher LET. The effect was more pronounced at smaller doses per fraction. Experimental survival fractions were adequately predicted using a linear quadratic formalism assuming full repair between fractions. Data were also used to validate a parameterized variable RBE model based on linear a parameter response with LET that showed considerable deviations from clinically predicted isoeffective fractionation regimens. The RBE-weighted absorbed dose calculated using the clinically adopted generic RBE of 1.1 significantly underestimates the biological effective dose from variable RBE, particularly in fractionation regimens with low doses per fraction. Coupled with an increase in effective range in fractionated exposures, our study provides an RBE dataset that can be used by the modeling community for the optimization of fractionated proton therapy.
Permanent Link: http://hdl.handle.net/11104/0260056