Quantification of the impact of electrons transport model on DVH metrics and radiobiological indices for lung radiotherapy plans

Abstract

Introduction and purpose to evaluate and quantify the impact of the calculation of electrons transport on dose distribution and radiobiological predictions for lung radiotherapy. Materials and methods The dose was calculated using the former Modified Batho (PB-MB) method and the Anisotropic Analytical Algorithm (AAA). Data derived from DVH, for target and lung, were compared. To compare dose distribution, 2D gamma ( γ ) index was applied. The radiobiological indices, TCP and NTCP, were compared using Lyman and EUD models. Spearman’s rank test was used to explore the best correlation coefficient ( ρ ) predicting the dose difference. The bootstrap method was used to estimate the 95% confidence intervals, and Wilcoxon paired test to calculate p -values. Results For the same prescribed dose, the plans generated with AAA predicted less dose and a more heterogeneous dose distribution inside the target, with p p γ analysis showed that the difference between MB and AAA could reach up to ±10% confirming the results obtained from TCP/NTCP. The data showed a good correlation between TCP with D95%, as well as NTCP with mean dose, V20 and V30, with ρ > 0.7. Conclusion The electrons transport, taken into account by AAA, showed a significant impact on delivered dose, dose distribution and TCP/NTCP. Readjusting the prescribed dose and a better optimization to protect the organs at risks should be considered and discussed when using new algorithms as AAA type. Disclosure None.