Grid Therapy: Impact of Radiobiological Models on Calculation of Therapeutic Ratio Publisher



Gholami S¹ ; Nedaie HA^{1, 2} ; Meigooni AS³ ; Longo F⁴ Show Affiliations
Source: IFMBE Proceedings Published:2015

Abstract

The purpose of this study is evaluation of the impact of radiobiological models in therapeutic ratio (TR) calculation of spatially fractionated (Grid) radiotherapy for different tumor cells. A Monte Carlo technique was employed to calculate the dose distributions of a Grid collimator in a 6 MV beam. The linear-quadratic (LQ) and modified linear quadratic (MLQ) models were used separately to evaluate the therapeutic ratio for different tumor cells (Melanoma, Squamous cell carcinoma (SCC), Adenocarcinoma and Sarcoma). Different maximum dose sizes (10 Gy, 15 Gy and 20 Gy) are considered. For each dose the equivalent uniform dose (EUD) is obtained. The EUDs and TRs for all different doses were derived through the LQ and MLQ models. Calculated therapeutic ratios from two models were compared. The results of TRs calculations from both LQ and MLQ have less than 5% difference. EUDs were varied between 2.19 Gy and 3.87 Gy. The TR was dependent on the prescribed dose, cell survival fraction at 2Gy dose (SF2) and radiobiological model parameters. © Springer International Publishing Switzerland 2015.