| 摘要 |
The invention relates to a method of processing data for Fourier transform X-ray CT which operates at high speeds and economically, effects the polar coordinates/Cartesian coordinates transformation at high speeds as well as the two-dimensional Fourier inverse transformation at high speeds, and helps markedly decrease the capacity of data memory needed for the transformation and the capacity of the control memory. According to this method, projection data of each view of parallel beams are found for each direction, these data are subjected to the Fourier transformation to find frequency components F( omega , theta ) on the polar coordinates omega - theta consisting of a frequency variable omega and an angle variable theta , the components are converted to frequency components G( xi , eta ) on the Cartesian coordinates xi - eta through the polar coordinates/Cartesian coordinates transformation, and the frequency components G( xi , eta ) are subjected to the two-dimensional Fourier inverse transformation to find a reconstituted image on the Cartesian coordinates x-y in a real space, wherein the frequency components obtained by the combination of the theta -direction and the ( theta +180 DEG )-direction are used as complex conjugates relative to the origin, the polar coordinates/Cartesian coordinates transformation is effected for only the upper half to lower half or for only the right half to left half of the two-dimensional frequency plane such that the polar coordinate/Cartesian coordinate transformation results in a complex conjugate, the Fourier inverse transformation is effected using the frequency components of the above regions only, and the results of the remaining Fourier inverse transformation are found by utilizing a relation of complex conjugates. |
