数字合成X线体层成像中轴向强度衰减的校正

作为新型医学成像技术，数字合成X线体层成像(DTS)技术有助于分辨重叠的成像组织并精确定位组织病变。DTS技术采用重建速度快、图像质量高的滤波反投影算法重建出冠断面的断层图像。但由于DTS投影数据集的不完整性，因此利用滤波反投影算法重建出的图像其强度在旋转轴方向上存在着类似帽状衰减现象。分析了X线源锥束角度对DTS图像中轴向强度衰减的影响，在此基础上引入了一种反余弦加权的强度衰减的校正方法。为验证校正方法对降低DTS图像中轴向强度衰减的效果，利用搭建的DTS系统在不同的X线源锥角下对乳房仿体进行了实验。结果表明，该校正方法能有效地降低DTS重建图像中的轴向强度衰减程度。

Correction of Axial Intensity Drop for Digital Tomosynthesis Reconstructed Image

As a new and developing medical imaging technique, the digital tomosynthesis imaging (DTS) can provide researchers with confidence to distinguish the overlapping lesion tissue and make exact lesion-localizing. DTS employs the filtered backprojection algorithm for its rapid reconstruction speed and high reconstruction quality and reconstructs a series of the coronal images. However, the digital tomosynthesis insufficient dataset causes the hat-like intensity drop in its filtered backprojection reconstructed images along the rotation axis. The cone angle impact on the digital tomosynthesis axial intensity drop is analyzed and a reciprocal-cosine weighted intensity correction is introduced. To validate the effect of the axial intensity drop correction method, a DTS system is designed and built up and the anthropomorphic breast phantom is reconstructed with the reciprocal-cosine weighted correction method under different cone angle respectively. The reconstruction results demonstrate that the correction method can effectively minimize the axial intensity drop in digital tomosynthesis reconstructed images.