An Efficient Estimation Method for Reducing the Axial Intensity Drop in Circular Cone-Beam CT

Table 1

Variable glossary.

𝐷	Distance from the X-ray source to the rotation center
𝐷𝑜𝑑	Distance from the rotation center to the detector
𝑓	Scanned object
𝑓𝑐	Estimation of 𝑓𝑁
𝑓FDK	Reconstruction using the FDK algorithm
𝑓𝐻	Correction term in the Hu-FDK algorithm
𝑓𝑁	Missing information in the circular CB trajectory
𝑔0	Ramp filtering kernel
𝑔ℎ	Hilbert transform kernel
𝑝	CB projection image
𝑝𝐹	Ramp-filtered image of 𝑝𝑚
𝑝ℎ	Intermediate function defined in (17)
𝑝𝑚	Projection image reconstructed from partial data of 𝑆^′𝑝𝑝
𝑝𝑝	Parallel-beam projection image
𝑝𝑣	Projection image on the virtual detector (see Figure 1)
𝑅𝑓	Radon transform of an object 𝑓
𝑆𝑝	Weighted sinogram of a projection image 𝑝
𝑤	Map function defined in (7)
𝛼	Angular parameter of 𝑆𝑝
𝛽	CB projection angle
𝛾𝑚	Full fan angle
𝜌	Displacement parameter of 𝑆𝑝