质子束治疗中非均匀组织的等效水厚度修正研究

非均匀组织等效水厚度修正是研究质子放射治疗的重要组成部分, 利用蒙特卡罗Fluka2011.2程序模拟了不同能量(50–250 MeV)的质子束入射到不同介质中的输运过程, 总结出了在不同介质中质子束初始能量与质子束Bragg峰深度关系, 并拟合出质子束在介质中的等效水厚度修正公式. 结果表明, 对不同能量的质子束入射到非均匀组织中, 通过拟合公式计算出Bragg峰深度值与Fluka模拟的质子束Bragg峰的位置相差在1 mm 之内. 如果建立起介质和水的Bragg峰比与电子密度比关系的数据库, 该公式有可能用于临床上的质子放射治疗的剂量计算中. 关键词： 蒙特卡罗 质子治疗 等效水厚度 Bragg 峰

Study of inhomogeneous tissue equivalent water thickness correction method in proton therapy

The inhomogeneous tissue equivalent water thickness correction method is an important part of research in proton radiotherapy. In this paper, we simulate the transport processes of a high-energy proton beam being injected into the water and other materials using Monte-Carlo multi-particle transport code Fluka, and according to the energy deposition distribution we obtain the depth of the Bragg peak when the protons are injected into different materials. Then we fit an analytic formula (R = αE₀^p) to the relationship between initial proton energy and the depth of the proton Bragg peak in different materials. It is found that for the different energies of proton beam being injected into non-uniform organization, the difference between the Bragg peak depth from fitting and the depth of the proton beam Bragg peaks from Fluka program is less than 1 mm. If we can establish a database about the relationship of Bragg peak ratio between medium and water, with electron density, then the equivalent water thickness correction method will be able to applied to the dose calculation of for homogeneous medium in proton therapy.