Evaluation of Dose Perturbation Due to the Different Dental Implants for Head and Neck Cancer Electron Therapy

Background or Introduction: Head and neck cancer patients usually have dental prostheses over the age of ۵۰ years. In some cases, electron therapy is used to treat head and neck cancer. The presence of a dental implant across the irradiation beam can potentially disturb the delivered dose distribution. Radiation scatters from high-density and atomic number materials cause tissue complications in the oral cavity. In this study, the effect of different commercial dental implants on absorbed dose was investigated in electron beam therapy of patients with head and neck cancer.Material and Methods: The LINAC head, dental implants, crown, mandible, and phantom are simulated precisely by MCNPX (۲.۶.۰). Six different implant materials, including Titanium, Titanium alloy, Zirconia (Y-TZP), Zirconium oxide, Alumina, and PolyetherEtherKetone (PEEK), were investigated in sizes of ۰.۳۵ cm in diameter and ۱.۶ cm in height. The ۶ and ۹ MeV electron beams were used in ۱۰x۱۰ filed size. Present depth doses (PDDs) and dose profile curves were calculated and compared with and without different implants.Results & Discussion: According to the PDD and profile curves, the highest and lowest increasing doses occurred in Y-TZP (۱۱۴.۴۴% and ۱۰۸.۶۹% for ۶ and ۹ MeV, respectively) and PEEK (۱۰۴.۸۵% and ۹۸.۸۴% for ۶ and ۹ MeV, respectively) directly in front of the implant, respectively. Removing an implant from the jaw can avoid increasing the dose in front of the implant, but this causes an increasing dose rate behind the implant in both energies.Conclusion(s): The amount of dose perturbation due to the dental implant's presence depends on the beamenergy, mass density, and atomic numbers of implants. Maximum and minimum increased doses wereestimated for Y-TZP and PEEK implants, respectively. Considering the accurate correction factor in electronbeam therapy is essential to estimate the correct dose delivery in the treatment planning system (TPS).

Keywords:

Radiotherapy , Electron therapy , Dental implant , Monte Carlo simulation , Dose distribution