Estimation of the risk for the second cancers induction in healthy tissues during the radiation therapy of liver’s tumor

The aim of this study was to estimate the delivered doses to tissues and organs around the liver tumor during radiotherapy and to determine organs with a high probability of secondary induction cancers. This study was carried out using Monte Carlo method.
The used Phantom, the ORNL phantom is for an adult female. The volume of the tumor is as much as 30% of the liver tissue.In the initial step of this study, we will focus on simulating the linear accelerator of Varian 2100 6MV and by comparing the output results with the calculated values;​​ we will make sure that the results of MCNPX code are sufficiently accurate. In the next step, the corrections are considered in phantom and Monte Carlo technique was used for radiotherapy. The dose calculations was done for 38 organs. According to the obtained results in this simulation, the reached doses to other tissues surrounding tumor was in the range of 0.01-13.07%. Among the examined organs, the healthy tissue of the liver, kidney, the left part of bone_rib cage, the right part of bone_rib cage, adrenals pancreas and lung have received 88, 24.5, 24.2, 18.8, 15.9, 7, 5 cGy, respectively. Due to the linear relationship between the dose received in each organ and the risk of cancer of the organ in subsequent years, in the BERT model, the kidneys have a higher risk of secondary cancers than other organs. In calculating of the risk by Monte Carlo method at a given time, the healthy part of the liver has the highest risk of inducing secondary cancers, and the risk of inducing secondary cancers for kidney, the right part of cage, the left part of cage and adrenal glands were 81, 48, 36 and 18 percent, respectively. Secondary cancer induction is more likely for patients who require more therapy for effective radiotherapy than other patients.