Motion correction of PET images using multiple acquisition frames

Positron emission tomography (PET) is a relatively lengthy brain imaging method. Because it is difficult for the patient to stay still during the data acquisition, head motion during scans are a source of image degradation. To reduce the degradation, a simple data acquisition technique is described. This technique associates the incoming data with the real-space position of the head. It consists of constantly monitoring the head position during PET studies and comparing the head position to the initial head position associated with the current acquisition frame. Every time the maximum RMS displacement within the field of view (FOV) is larger than a specified threshold value, the data acquisition system starts acquiring the data into a new frame. A complete study is then acquired over several frames. The number of frames required depends on the motion of the head during the study and on the threshold value. At the end of the study all the acquired frames are reconstructed independently and each image is rotated and translated according to its associated initial head position. When these images are added together, it will produce a final image with fewer motion artefacts