Mahdipour Seyed Ali, Mowlavi Ali Asghar
Physics Department, Hakim Sabzevari University, Sabzevar, Iran.
Physics Department, Hakim Sabzevari University, Sabzevar, Iran; ICTP, Associate Federation Scheme, Medical Physics Field, Trieste, Italy.
Med Dosim. 2016 Summer;41(2):118-25. doi: 10.1016/j.meddos.2015.10.005. Epub 2016 Jan 29.
Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth-dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8MeV proton, 190.1MeV alpha, and 1060MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam׳s Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.
质子和碳离子等离子束放疗已用于眼部葡萄膜黑色素瘤的治疗多年。在本研究中，我们开发了一种用于蒙特卡罗肿瘤治疗模拟的新型人眼体模，以用于GEANT4工具包。已在该体模中计算了具有相同射程的质子、α粒子和碳离子入射束的总深度剂量分布。此外，还计算了每个初级束的次级粒子沉积能量。比较了在到达肿瘤中心的靶区域中具有相同射程的47.8MeV质子、190.1MeVα粒子和1060MeV碳离子的剂量曲线。计算并比较了每个入射束的被动散射扩展布拉格峰（SOBP）以及包括中子、γ射线和正电子在内的次级粒子的通量曲线。碳离子束布拉格峰的高锐度和低横向展宽是其在强子治疗中的优势，但它在布拉格峰后的尾部存在剂量泄漏以及中子产生强度高的缺点。然而，由于散射导致束展宽，质子束与肿瘤形状具有良好的适形性，对于大尺寸肿瘤可能是一个不错的选择。
