Simulation on the emergence of metastases in breast cancer radiotherapy patients using Monte Carlo N-particle (MCNP)

Abstract

The distribution of radiation doses in cancer patients who receive radiotherapy treatment depends on the distance of the cancerous organ to the radiation source, the type of organ including the density of the organ and the atoms of the organ. Even though radiation exposure is focused on the cancer that will be irradiated, the surrounding healthy organs still have a great chance of getting radiation exposure. Healthy organs that can be exposed and within a certain period of time are thought to have the opportunity to experience metastases. Simulation of the chance of occurrence of metastases in healthy organs around cancer in patients receiving radiotherapy has been done using Monte Carlo N-Particle (MCNP) simulations by the ORNL-MIRD phantom model. The simulation is aimed at breast cancer patients by adding cancer cells to the phantom in the left breast at a depth of 2.5 cm at the coordinates of 8.63-9.5 46.87. The simulation results are converted into dosimetry quantities to describe the impact of radiotherapy on healthy organs. The final measured dose is the effective dose. The simulation results show that the distribution of doses in the patient's body is very wide, covering all the organs under review, with the highest dose rate value found in cancer cells as much as 0.009079 Gy/s. The healthy organs that received the highest effective dose were the lungs, as much as 5.52 mSv followed by breasts of 5.28 mSv, it is estimated that the chance of lung metastases in patients with cancer is considered large.