X射线相位衬度成像具有极高的灵敏度,能探测到轻元素样品的内部结构,在医学、生物学和材料科学等众多领域显示出良好的应用前景。光栅成像模式可使用非相干光源进行X射线相位衬度成像,开创了非相干光源相衬成像新纪元。将螺旋CT的概念引入光栅相衬成像领域,将螺旋CT的高效率优势与光栅相位成像的高衬度优势相结合,发展X射线螺旋相位CT方法。通过分析螺旋轨迹非相干光源相位成像的特点,提出一种扇形束螺旋条件下的相位信息提取方法;而后借鉴希尔伯特滤波反投影重建算法的思想,得到扇形束螺旋相位CT重建算法。该算法利用折射角像直接重建物体的相位项。计算机仿真实验证明了该算法的有效性。

X-ray phase contrast imaging is of high sensitivity,with which the internal structure of light elements can be observed. It shows the promising application prospects in many fields such as medicine,biology and material science,etc. Grating imaging successfully used the incoherent source,which brought us into a new epoch of incoherent source phase contrast imaging. A new phase-contrast CT method is developed by introducing the helical scanning into the field of phase-contrast imaging. By analyzing the feature of incoherent source in helical trajectory,a fan-beam helical phase contrast extracting method is presented and by referring to Hilbert′s filtered backprojection reconstruction algorithm,the fan beam helical phase-contrast imaging CT reconstruction algorithm based on grating imaging is proposed. Phase information is reconstructed directly by the refraction projection according to the proposed algorithm computer simulations and performance analysis demonstrate the efficiency of the proposed method.