Development of motion correction technique for PET study using optical tracking system

Head movement during positron emission tomography (PET) studies causes loss of image quality and quantity and is problematic for brain PET study. During the PET scan, the head of the subject is often fixed by a head holder. However, the head holder is not perfect and it is sometimes difficult to use the head holder for a less cooperative patient. Moreover, head fixation might generate unwanted signals in neural activation studies. There are several software packages, such as AIR and SPM, offering software tools to correct head motion between two scans. These tools, however, cannot correct head motions during scanning. We developed a system to correct the head motion during PET scanning using list-mode acquisition and an optical tracking system. To compensate for escaped photon from the FOV of the PET scanner, the concept of a “virtual ring” was introduced. The present system has the potential to do real-time motion correction during PET scanning and makes it possible to scan a subject without any head fixation, which provides a new aspect of brain research using PET.