局部扫描情况下多项式拟合的X射线硬化校正

X-ray beam hardening correction based on polynomial fitting in local scanning

在进行X-CT成像时,容易诱发射束硬化效应。通过多项式拟合建立起多色投影同透射距离的数学模型,然后将多色投影校正为单色投影,是一种简单高效的射束硬化校正方法。对于局部扫描的情况,在重建图像域通过正投影方法计算得到的透射距离不再代表真实的射线穿过长度,拟合数据不再有效。因此借助一圆柱模体,根据圆柱自身的几何特性,通过解析的方法计算得到射线真实的透射距离,并用于射束硬化校正。实验结果表明,该方法能够有效抑制射束硬化引起的图像伪影,提高CT重建图像质量。

Beam hardening effect would be induced due to wide energy spectrum of X-ray.One efficient beam hardening correction method is building a mathematical law between poly-energetic projection and intersection length,which can be calculated by forward projection in reconstructed images domain.However,for local scanning,the intersection length obtained by forward projection is no longer equal to the real distance at which X-ray passes through the object,and the data of mathematical fit are not valid.Hence,a cylindrical phantom is used.Utilizing the geometrical character of cylinder,the true distance X-ray passing through the object is calculated analytically.Experimental result shows that beam hardening artifacts are suppressed by our approach.