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Spline Interpolation in Filtered Back Projection Algorithm

M. Venu Gopala Rao, S. Vathsal

Abstract



In this paper we consider spline interpolation techniques to improve the quality of Computerized Tomographic reconstructed image. In particular, we propose to link the filtering design with interpolation that is applied to sinogram. The key idea is to combine the ramp filter with spline fitting process into a single filtering process. In this paper we propose two interpolation techniques, spline interpolation and fractional spline interpolation techniques. In the first approach we show that the spline interpolation (order n =1) improves the quality by 2dB over the conventional linear interpolation. In the second approach we perform an explicit discretization by observing that the ramp filter is equivalent to a fractional derivative operator that can be evaluated analytically. This allows us for exact implementation of the ramp filter and improves the quality of the reconstructed image by an additional 2dB.

Keywords


Tomography, filtered back projection, ramp filter, spline interpolation, fractional spline interpolation.

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