Investigation of effects on dose distrubition of the biomaterials placed into human body with Monte Carlo method and dosimetrically in radiotherapy

Radiotherapy plays an important role in the treatment of cancer patients. In the treatment of cancer, radiation should be given the right way to the patients. For this reason, dosimetric studies are critically important in radiotherapy. During the treatment of patients with cancer, prosthesis can affect the distribution of a homogeneous radiation dose, due to tissue density difference between prosthesis and tissues may lead to areas of high or low dose. Therefore, in this study, biomaterials implanted into the body as prosthesis and the effects on radiotherapy dose distribution were investigated. Silicon, titanium, titanium alloy, steel, CoCrMo alloy, polyethylene, PMMA (Poly (methyl methacrylate)) and alumina biomaterials were used in the study. The percentage depth doses obtained with Monte Carlo method were compared with the percentage depth doses obtained with dosimetric measurements using phantoms. Additionally, the percantage depth doses obtained with Eclipse TPS were compared with the other two methods and the accuracy of TPS were investigated. The properties of PMMA and polyethylene and silicone biomaterials were very close to the tissue.The difference between water and these biomaterials were not statistically significant in terms of dose distribution in radiation therapy. In case of the cancer patient that has implant was treated with radiation, these biomaterials act as tissue and not lead to problems in radiation dose distribution. The other metal biomaterials that are titanium, titanium alloy, steel and CoCrMo alloy and alumina do not act as tissue and largely caused by changes in dose. At the result of the study, the PBC algorithm in Eclipse TPS could not predicted accurately radiation dose for the patients have high Z hip prostheses. The results show that the use of the MC-based treatment planning system for accurate dose calculation should be used in the presence of high Z prostheses.