以代數重建法重建電腦斷層掃描之實作改良

Abstract

電腦斷層掃描取像已在許多領域得到廣泛的使用。其影像重建的方法以濾波反投影以及代數重建法為主，濾波反投影以其快速的得到重建結果獲得青睞，而代數重建法則以較好品質而著名。在本篇論文中，我們提出了兩個改良代數重建法的方法。第一，我們修改了反投影的步驟，從原本的均勻反投影改成非均勻的方式。第二，以計算面積的方式實作反投影，可以得到較精確的權重質。兩種方法皆改進了影像品質，且第一種方法加快了收斂速度。

Computed tomography imaging is widely used in many fields. The image could be reconstructed by two main methods, Filtered Back Projection (FBP) and Algebraic Reconstruction Techniques (ART). The FBP method is fast and the quality of the image that is reconstructed by the ART method is better. In this thesis, we propose two methods to improve the ART method. First, we modify the process of back projection of the ART method. Instead of the uniform back-distribution, we use the non-uniform one. Second, we propose an area-based calculation for the weight in the implementation of back projection. Both methods improve the quality of the image and the first one makes the ART method converge faster than the classic implementation.