Abstarct: Lung cancer is one of the most common types of cancer with a high mortality rate among men and women. The disease causes regional carcinoma and mextastasis by invading the arteries and involving the lymph nodes. Radiation therapy using an accelerator source is one of the most effective ways to treat a tumor in the lung tissue. Control of secondary abnormalities during or after the treatment process in the target tissue and other vital organs requires consideration of all aspects when implementing the treatment protocol. In the present study, simulation calculations of the lung cancer treatment process were performed using the Monte Carlo method and the MCNPX6/2 transport code. For this purpose, the Female ORNL phantom was first modeled, including tumor tissue in the right lung wall, and a Siemens LINAC linear accelerator. In the next step, the validation of PDD curves and dose profiles in the water phantom was performed in a 10×10field and in the working energy range. The simulation conditions are as close as possible to the treatment plan of the patient with a prescribed dose of 66Gy to the tumor during 33treatment sessions. The absorbed dose to the lung tumor bed and the surrounding clinical volumes were calculated by electron beam emitted from the accelerator source using the Tally *F8. In 6MV energy spectrum, the highest absorption dose was 22/1Gy in the energy range of 6/5MV and in the 18MV energy spectrum, the highest absorption dose was 7/1Gy in the energy range of 4/15MV. According to the results, it can be said that with increasing depth and voltage, we will face a decrease in the dose received from the accelerator .