Among all kinds of reconstruction-algorithms, approximate algorithms are widely used in practice. Among various based in filtered back-projection algorithms, FDK(Feldkamp -Davis-Kress) algorithm is the mainstream methods all the times.

• 在各种重建算法中，近似重建算法在实际中应用较广泛，其中基于滤波反投影的FDK(Feldkamp-Davis-Kress)近似算法是实际应用中的主流算法。