X射线TICT在复合材料工件检测中的能谱硬化修正模型

X射线TICT中，由于X射线能谱具有多色性, X射线在透射物质时，能量较低的射线优先被吸收，也即较高能量的X射线的衰减系数比较低能量的X射线的衰减系数小，射线随透射厚度增大，变得更易穿透，也就是发生了能谱硬化现象。如不加修正，必引起赝像。文中对能谱硬化现象进行了分析，探讨了X射线TICT在复合材料工件检测中, X射线的衰减系数与透射厚度的关系, 并根据Beer定律和X射线与复合材料作用的特点, 推导出X射线TICT在复合材料工件检测中, 严谨精确的能谱硬化修正模型及其修正方法。对修正后的衰减系数再做卷积反投影重构, 即可有效消除能谱硬化造成的影响。

Hardening Correction Model of Energy Spectrum for X-Ray TICT in Testing Composites Workpiece

In the case of a polychromatic source in X-ray TICT, the variation of attenuation coefficient with energy leads to low energy radiation being absorbed preferentially. In other words, the higher the energy, the lower the attenuation coefficient. With the transmission thickness augmenting, it is easier for X-ray to transmit the matter. The phenomenon is energy spectrum hardening. Thus, hardening correction has to be done. In the present paper, not only is energy spectrum hardening analyzed by theory and the relation stated between attenuation coefficient and transmission thickness in testing composites workpiece, but also the precise accurate theory model for hardening correction of energy spectrum and theory method are reasoned out in testing composites workpiece, which results from Beer's law and the characteristics of X-ray interaction with composites. Then, the attenuation coefficient that has been corrected is used for product back-projection reconstruction. Thus, the effect caused by X-ray beam hardening is wipped out effectively in testing composites workpiece.