Reduction of distortion in spiral CT by tilted fan beam data acquisition

The spiral scan X-ray CT is useful for high speed acquisition of three dimensional image data. In image reconstruction of spiral scan data, a set of sequential data is used and the data are interpolated to produce projection data which reconstruct an image of a given cross section. This interpolation sometimes causes artifacts in the reconstructed image. We propose a new data acquisition method which minimizes the effect of the scanning slice position in the axial direction. The proposed method inclines an X-ray detector array in the direction of rotation. The tilted angle is defined as arctan(θL/2Rπ tan θ), where L is the distance a table moves per rotation and R is the radius of rotation of the X-ray source. The angle B is the orthogonal projection of the half of a fan angle onto the parallel beam projection plane. Simulation results showed that our method eliminates the low frequency distortion and improves the spatial resolution in the axial direction