【摘要】 为了开发出有效的医学诊断X射线CT(计算机断层扫描)射束硬化校正方法,结合X射线源能谱分布以及数学CT模体内各区域的几何形状和材料成分,提出一种宽能谱X射线投影解析计算方法.首先在仅考虑人体组织的前提下将CT值映射为材料成分,然后采用解析方法确定区域边界,最后根据X射线能谱分布计算投影数据.与线积分投影比较,该方法不但能够生成更真实的投影,而且能够为射束硬化校正与CT重建研究提供统一的投影数据.FORBILD头部模体实验结果表明,骨校正的骨区域CT值不一致误差比水校正的小4~5 Hu,比单能谱重建的大5~6 Hu.更多还原

【Abstract】 To develop an efficient beam hardening correction for medical diagnostic X-ray CT(computed tomography),an analytic calculation method was proposed to simulate polychromatic X-ray projections.The method combines the energy spectrum distribution of X-ray source,geometrical shapes and material compositions of sub-regions of phantoms.Firstly,CT values are mapped into material compositions under the precondition that only human being tissues are considered.And then,boundaries of sub-regions are determined by the proposed analytic method.Finally,projections are calculated according to the energy spectrum distribution of X-ray source.Compared with the linear integral projecting,the proposed method can not only generate more realistic projections,but also provide a unified projection data for beam hardening correction and CT reconstruction.Experiments of FORBILD head phantom show that the CTvalue inconsistency error of bone correction in bone region is lower than the water correction around 4-5Hu,but higher than the monochromatic reconstruction around 5-6Hu.更多还原