Dosimetric quantities and cell survival for spatially fractionated radiation therapy

Purpose: Spatially Fractionated Radiation Therapy (SFRT) is characterized by large differences in peak and valley doses. Preclinical clinical studies suggest that biological mechanisms lead to differential normal tissue tumor response compared uniform irradiation. We hypothesize evaluate effectiveness understand fundamental mechanisms, radiobiological rather than physical dose quantities should be utilized for comparisons. The aim of this work determine whether Equivalent Uniform Dose (EUD) a superior predictor cell survival absorbed dose. Methods: Absorbed parameters were the assess their predictive value relative SFRT with X-rays. A Bayesian bootstrap technique was model uncertainties fit human fibroblast (MRC5) two lines (LN18 A549). evaluated through measurements error modeling profiles. dimensionless Relative Effectiveness Factor (REF) proposed quantify between Results: For all lines, after matched irradiation within estimated at equal values EUD. Average showed poor correlation vitro survival. REF factor dependent suggests enhanced killing both (1.14 ± .08 LN18, 1.32 .13 A549 8 Gy EUD) SFRT. Normal fibroblasts reduced (.58 .06 MRC5). Synthetically generated profiles revealed EUD are dominated uncertainties, especially high Discussion : more average or Valley close > 10 has advantage being independent parameters. novel useful metric compare quantitative Conclusion recommended comparisons results an increase normal-human cells