Development of a motion detecting system for respiratory-gated PET using laser optical displacement sensor

A respiratory motion during whole-body imaging has been recognized as a source of image degradation and induces distortions in positron emission tomography (PET) study. The aim of this study is to evaluate respiratory motion using lung simulator and to develop a respiratory motion detecting system using optical laser sensor. We utilized a commercially available laser optical sensor to detect respiratory motion during PET scanning. Each respiratory cycle is divided into 4 bins defined as average peak interval and irregular peak within the patient´s breathing motion. The acquired data within the time bins correspond to different positions within the breathing cycle and stored for the post motion correction. Artifact of breathing motion was evaluated with the phantom study. In the images of a human subject, the blurring artifact due to breathing motion was divided by our detecting system. This technique improves the quantitative specific activity of the tracer which is distorted by the respiratory motion.