基于蒙特卡罗模拟的射束硬化校正方法

Beam Hardening Correction Based on Monte Carlo Simulation

传统的射束硬化校正方法,通常需要针对每一种材料测量该材料对射线的吸收曲线．由于吸收曲线对实验条件有很大的依赖性,每当改变X光机电压或者被测工件的材料等条件时,需要重新测量吸收曲线才能完成硬化校正过程．这种方法费事费时．本文提出了基于蒙特卡罗模拟计算物质吸收曲线的硬化校正方法．实验中,分别用本方法和传统的硬化校正方法对铝工件进行硬化校正,经过比较,确认本方法是有效的．然后用该方法对不同材料(铝、铁和铜)的工件进行校正．实验结果表明,本方法能有效消除各种材料工件图像中的硬化伪影,是快速的和切实可行的．

For the empirical beam hardening correction in computerized tomography （CT）, it is necessary to measure an attenuation curve for the material. The attenuation curve depends on the X ray machine operation parameters and object material, etc. If any measuring condition changes, a new attenuation curve has to be measured. This approach is time consuming and difficult to implement. A new method of beam hardening correction is presented in this paper, which is based on Monte Carlo simulation of the attenuation characteristic. An aluminium object is scanned and the projection data is corrected by the empirical beam hardening correction and by the simulation based correction. The results of the reconstructed images confirm the correctness of the simulation based method. The simulation based correction has been applied successfully to CT projection data of several test samples, with the material of aluminum, steel and copper.