基于最优投影逼近法的X射线硬化校正
An X-Ray Beam Hardening Correction Method Based on Optimal Projection Approximation
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摘要: 射束硬化是导致CT重建图像下降的物理原因之一。该文分析了射束硬化校正的常用方法，比如线性化方法、基于原始投影正弦图的校正方法，并在此基础上提出了一种适用于非圆形检测对象的最优投影逼近法。该方法将射线穿透距离最短的扫描角度作为最优投影角度，将该角度下的原始投影作为校正标准，并建立硬化校正方程，通过牛顿迭代法解得各个投影角度下的校正值。实验结果表明，采用本文方法进行硬化校正后，由射束硬化引起的杯状伪影得到较好地抑制。该方法具有自适应性，执行效率高，并且可以推广到多材质扫描对象的硬化校正。Abstract: Beam Hardening effect is one of the reasons that degrade the quality of CT reconstructed images . This paper has analyzed some common beam hardening correction methods ,such as linear method ,correc‐tion method based on original projection .For non‐rounded objects ,an optimal projection approximation correction method has been proposed .Optimal projection view is assumed as one w here the distance w hich X‐ray passes through the object is shortest .A beam hardening correction equation has been built on the base of the projections obtained at optimal projection view .Correction solutions of each projection view have been obtained by Newton iteration .An experiment has been performed .The result shows that cup‐ping artifact induced due to beam hardening was suppressed by our approach .In addition ,proposed meth‐od is efficient with self‐adaption ,and is easy to extend to beam hardening correction of multi‐material ob‐ject s .
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