In computed tomography, high attenuation occurs when x-rays pass through a dense region or a long path in the scanning object. In this case, only limited photons reach the detector, which causes photon starvation artifacts. The artifacts usually appear as streaks along the directions with high attenuation. It might lower the discrimination of minor structures and lead to misdiagnosis. Applying a local filter to the projection data adaptively is a common solution, however, if the parameters of projection-based filter are not well selected, new artifacts and noise might appear in the final image. In this paper, a post image processing technique was developed to suppress the photon starvation streak artifacts. Based on the directional characteristics of streaks, a semi-adaptive anisotropic diffusion filter was applied to the high frequency sub-bands after wavelet transformation (WASA). Qualitative and quantitative experiments were performed on phantom data and clinical data to prove the effectiveness of this method for photon starvation artifact suppression.

在计算机断层扫描中，当 X 射线穿过扫描对象中的密集区域或长路径时，会发生高衰减。在这种情况下，只有有限的光子到达探测器，这会导致光子饥饿伪影。伪影通常沿具有高衰减的方向显示为条纹。它可能会降低对微小结构的辨别力并导致误诊。将局部滤波器自适应地应用于投影数据是一种常见的解决方案，但是，如果基于投影的滤波器的参数选择不当，最终图像中可能会出现新的伪影和噪声。在本文中，开发了一种后图像处理技术来抑制光子饥饿条纹伪影。根据条纹的方向特征，将半自适应各向异性扩散滤波器应用于小波变换后的高频子带（WASA）。对模型数据和临床数据进行了定性和定量实验，证明了该方法对光子饥饿伪影抑制的有效性。