Department of Biomedical Engineering, University of California at Davis, GBSF 2303, Davis, California 95616, USA.
Med Phys. 2010 Feb;37(2):704-13. doi: 10.1118/1.3284980.
The quality of tomographic images is directly affected by the system model being used in image reconstruction. An accurate system matrix is desirable for high-resolution image reconstruction, but it often leads to high computation cost. In this work the authors present a maximum a posteriori reconstruction algorithm with residual correction to alleviate the tradeoff between the model accuracy and the computation efficiency in image reconstruction.
Unlike conventional iterative methods that assume that the system matrix is accurate, the proposed method reconstructs an image with a simplified system matrix and then removes the reconstruction artifacts through residual correction. Since the time-consuming forward and back projection operations using the accurate system matrix are not required in every iteration, image reconstruction time can be greatly reduced.
The authors apply the new algorithm to high-resolution positron emission tomography reconstruction with an on-the-fly Monte Carlo (MC) based positron range model. Computer simulations show that the new method is an order of magnitude faster than the traditional MC-based method, whereas the visual quality and quantitative accuracy of the reconstructed images are much better than that obtained by using the simplified system matrix alone.
The residual correction method can reconstruct high-resolution images and is computationally efficient.
在图像重建中，断层图像的质量直接受到所使用的系统模型的影响。对于高分辨率图像重建，准确的系统矩阵是理想的，但这通常会导致高计算成本。在这项工作中，作者提出了一种带有残差校正的最大后验重建算法，以缓解图像重建中模型准确性和计算效率之间的权衡。
与传统的迭代方法不同，传统迭代方法假设系统矩阵是准确的，该方法使用简化的系统矩阵重建图像，然后通过残差校正去除重建伪影。由于在每次迭代中都不需要使用准确系统矩阵进行耗时的正向和反向投影操作，因此可以大大减少图像重建时间。
作者将新算法应用于基于实时蒙特卡罗（MC）的正电子射程模型的高分辨率正电子发射断层扫描重建。计算机模拟表明，新方法比传统的基于 MC 的方法快一个数量级，而重建图像的视觉质量和定量准确性都明显优于仅使用简化系统矩阵的方法。
残差校正方法可以重建高分辨率图像，并且计算效率高。
