Correction of patient movement with a phase-only correlation method in a SPECT study

Patient movement during SPECT and PET data acquisition makes serious distortions in reconstructed images. In most conventional methods a correction of this movement is conducted in the sinogram space. However, the direction of movement occurs at an angle that is parallel to collimator holes, making it is difficult to detect the movement of an object. This paper proposes a new correction method of patient movement. This method basically uses a phase-only correlation method. We applied the phase-only correlation method to both a sinogram space and image space. That is, we apply a one dimensional Fourier transform to a measured sinogram and detect an angle at which a movement occurs with the phase information of neighboring projection data. After we detect the angle at which a movement takes place, we split the sinogram into two angular regions and reconstruct images corresponding to these angular regions. We also apply a one-dimensional Fourier transform to these reconstructed images and estimate the extent of movement. Next we replace the wrong projection data with correct data that are calculated by forward projection of the image positioned correctly. By reconstructing an image with a corrected sinogram we could obtain a distortion free image. This paper showed the validity of our method with some simulations.