Analytical and fine Monte Carlo Kerma coefficients evaluation for a wide range photon energy relevant to some chemotherapy agents

Abstract

Simultaneously combination of chemotherapy drugs and ionizing radiations has become a common treatment method for advanced cancers. Tumor irradiation in presence of chemotherapy drugs can affect deposited energy within tissue. Hence, to evaluate how chemotherapy drugs affect the absorbed dose within tissues during chemoradiotherapy, Kerma coefficient values for 26 anti-cancer agents were estimated for photon energies ranging from 1 keV to 20 MeV through analytical analysis and Monte Carlo (MC) simulation approaches.Estimation of Kerma coefficients through MC simulation relevant to different chemotherapy drugs was performed with MCNPX V.2.6.0 MC code. Besides, Kerma coefficient values were calculated using the reported mass energy absorption coefficients, as the theoretical method. Significant statistical test was also employed to evaluate the accordance of obtained Kerma coefficients by two considered methods.Simulation results were consistent with evaluated Kerma coefficients by analytical method which minimum and maximum mean relative differences are found for Bevacizumab and Methotrexate, respectively. Furthermore, a significant correlation is found with chemical composition of selected chemotherapy drugs at considered photon energy range. Fluorouracil showed the closest Kerma ratio to unity among the studied anti-cancer drugs. Kerma coefficient ratios for most of selected drugs were close to unity at higher energy regions (100 keV–20 MeV) while greater values were found at lower photon energies (below 100 keV).From the results, presence of these anti-cancer agents can impact Kerma coefficient and subsequently alter the absorbed dose within tissue during the cancer treatment with chemoradiotherapy technique.