Grid artifact reduction in radiography with arctan(1/2)-degree rotated grid

In order to reduce the grid artifacts in the digital radiography with stationary antiscatter grids, artifact frequency detection schemes should be adopted and appropriate band-rejection filters should be applied. However, by rotating the grid angle for certain grid densities and sampling frequencies, the artifact frequencies can be placed near the boundary of the frequency domain, and then the grid artifacts can be easily alleviated by applying a simple low-pass filter without any estimates of the artifact frequencies. In this paper, we propose a grid artifact reduction algorithm, which is based on rotating the grid and applying a low-pass filter. For the sampling frequency 7.194 lines/mm, an optimal rotate angle is arctan(1/2) ≈ 26.57° and the grid density is 102.2 lines/inch. Better performances are obtained for real x-ray images.