Enhancing the dose in radiation therapy with Cs-137 and Au-198

Enhancing the radiation dosage when performing a radiation therapy is affected by the type of the enhancing agent and its concentration. The aim of this study is to assess these effects by analyzing the enhanced radiotherapy process with testing the inclusion of different elements and different concentrations. Considering broad ranges for these two affecting factors, with different radiation sources, has never been addressed in prior studies. Two models are used; a simulation one, and a mathematical one. The simulation is made by the Monte Carlo N-Particle version 5 code. The human part considered in this study is the head, and the dosage is evaluated before and after adding the enhancing agent. Radiation sources of Au-198 and Cs-137 are used. The simulation results are compared to the mathematical model. An agreement is found regarding the general features, but the simulated values are deemed more realistic. The results of the mathematical model show underestimation compared to the simulation results due to the model's simplicity by considering only photons. Differently, the simulation scheme includes both photons and electrons, and considers the secondary interactions as well as the $\text{back}$-$\text{scattering}$ effects. For the radionuclide Au-198, and when using a concentration of 5 % for the enhancing agent with atomic number 92, the simulation result is higher than that of the mathematical model by about 7 %. The results also show that, in some cases, the atomic number of the enhancing agent is not the main factor to decide about the treatment plan. Moreover, depending on the treatment case, the current paper suggests that a combined-selection for the enhancing agent, its concentration and the radiation source has to be carefully made. The results of this study shed some more light on the general features of using enhanced radiotherapy.