峰谷比法测量等效胸壁厚度技术研究

发布时间：2018-08-02 21:39

【摘要】：Pu在人体肺部中的沉积常采用241Am进行替代测量，测量时胸壁厚度及成分对计算结果影响很大，这种影响用肌肉等效胸壁厚度（MEQ-CWT）进行统一标定。为测定这一物理量通常会引入医学成像设备，对人体胸部进行扫描得到几何胸壁厚度后，再结合肌肉和脂肪相关参数算出MEQ-CWT，这种方法程序复杂、增加额外成本且不能直接给出MEQ-CWT的结果。针对这一问题，本文采取峰谷比法，，研究利用肺部计数器测量放射性的同时对肌肉等效胸壁厚度进行直接测量。本论文主要研究的内容包括： 1、对峰谷比法测量肌肉等效胸壁厚度的问题进行了适当的简化，建立了简化模型和点源模型，并分别推导了两种模型下利用峰谷比计算MEQ-CWT的理论公式，利用MCNP程序模拟了简化模型下峰谷比与肌肉等效胸壁厚度间的函数关系，证明了峰谷比法测量MEQ-CWT的理论可行性； 2、对峰谷比法中的重要参量k因子进行了计算公式推导与蒙卡模拟验证，得到了k因子的计算方法。 3、利用点源模型进行了峰谷比法测量介质厚度的实验研究，设计了实验测量方案，进行了峰谷比法测量谱的解谱技术研究，获得了谷峰比测量铝片厚度的值，验证了方法的实践可行性。 4、应用肺部计数系统和仿真人体躯干模型，测量研究了人体肌肉等效胸壁厚度MEQ-CWT同谷峰比Q的关系，由点源模型理论公式计算了MEQ-CWT，并进行了误差分析，分析了峰谷比法理论公式在肺部Am存量估算中存在的不足，指出了利用峰谷比法测量等效胸壁厚度的可行方法。
[Abstract]:The deposition of Pu in human lung is usually measured by 241Am. The thickness and composition of chest wall have great influence on the calculation results. This effect is calibrated by muscle equivalent chest wall thickness (MEQ-CWT). In order to measure this physical quantity, the medical imaging equipment is usually introduced, the thickness of the geometric chest wall is obtained by scanning the chest of the human body, and then the MEQ-CWTs are calculated by combining the parameters of muscle and fat. The procedure of this method is complicated. Additional costs are added and the results of MEQ-CWT cannot be directly given. In order to solve this problem, the peak to valley ratio method is adopted to measure radioactivity in lung counter and to measure the thickness of muscle equivalent chest wall directly. The main contents of this thesis are as follows: 1. The problem of measuring the equivalent chest wall thickness of muscle by peak-valley ratio method is simplified, and a simplified model and a point source model are established. The theoretical formulas of calculating MEQ-CWT by peak-to-valley ratio under two kinds of models are derived, and the functional relationship between the ratio of peak to valley and the thickness of muscle equivalent chest wall under the simplified model is simulated by using MCNP program. The theoretical feasibility of MEQ-CWT measurement by peak-to-valley ratio method is proved. 2. The important parameter k factor in the peak-valley ratio method is deduced and verified by Monka simulation. The calculation method of k factor is obtained. 3. The experimental research on measuring the thickness of medium by peak-valley ratio method is carried out by using point source model, and the experimental measurement scheme is designed, and the despectral technique of peak-valley ratio method is studied. The practical feasibility of the method is verified. 4. Using the lung counting system and the simulated human torso model, the relationship between MEQ-CWT and the ratio Q of human muscle equivalent chest wall is measured and studied. Based on the theoretical formula of point source model, the MEQ-CWTs are calculated, and the error analysis is carried out. The shortcomings of the theoretical formula of peak-valley ratio method in estimating the lung am stock are analyzed, and the feasible method for measuring the equivalent chest wall thickness by using the peak-to-valley ratio method is pointed out.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R144

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