Radiation dose enhancement in skin therapy with nanoparticle addition: A Monte Carlo study on kilovoltage photon and megavoltage electron beams

• 作者: James C L Chow Xiao J Zheng
• 来源期刊: 世界放射学杂志：英文版（电子版）
• 学科: 医学
• 关键词: 皮肤治疗 蒙特卡罗模拟 NANOPARTICLE 剂量改进 光子和电子横梁
• 年，卷（期）: 2017,（2）
• 页码范围: 63-71
• 页数: 9页
• 分类号: R730.55

摘要

AIM To investigated the dose enhancement due to the incorporation of nanoparticles in skin therapy using the kilovoltage(k V) photon and megavoltage(MV) electron beams. Monte Carlo simulations were used to predict the dose enhancement when different types and concentrations of nanoparticles were added to skin target layers of varying thickness.METHODS Clinical k V photon beams(105 and 220 k Vp) and MV electron beams(4 and 6 MeV), produced by a Gulmay D3225 orthovoltage unit and a Varian 21 EX linear accelerator, were simulated using the EGSnrc Monte Carlo code. Doses at skin target layers with thicknesses ranging from 0.5 to 5 mm for the photon beams and 0.5 to 10 mm for the electron beams were determined. The skin target layer was added with the Au, Pt, I, Ag and Fe2O3 nanoparticles with concentrations ranging from 3 to 40 mg/m L. The dose enhancement ratio(DER), defined as the dose at the target layer with nanoparticle addition divided by the dose at the layer without nanoparticle addition, was calculated for each nanoparticle type, nanoparticle concentration and target layer thickness.RESULTS It was found that among all nanoparticles, Au had thehighest DER(5.2-6.3) when irradiated with kV photon beams. Dependence of the DER on the target layer thickness was not significant for the 220 k Vp photon beam but it was for 105 kV p beam for Au nanoparticle concentrations higher than 18 mg/m L. For other nanoparticles, the DER was dependent on the atomic number of the nanoparticle and energy spectrum of the photon beams. All nanoparticles showed an increase of DER with nanoparticle concentration during the photon beam irradiations regardless of thickness. For electron beams, the Au nanoparticles were found to have the highest DER(1.01-1.08) when the beam energy was equal to 4 MeV, but this was drastically lower than the DER values found using photon beams. The DER was also found affected by the depth of maximum dose of the electron beam and target thickness. For other nanoparticles with lower atomic number, DERs in th