Evaluation of Phased-Array Radar-Based Measurement of Respiration During PET/CT

Various techniques have been used to obtain respiration-correlated waveforms (amplitude as a function of time) for motion-compensated PET reconstruction and also for gated or triggered CT scans. In this study, a low-power UHF CW Doppler radar system was used, with antennas between the bed and the patient's back to direct RF radiation deep into the human body. The novelty of this work is the phased array sensor to steer the main beam radiation (transmission or reception) toward the diaphragm. The radiation's oblique entry into the body results in favorable SNR, less sensitivity to movements near the bed including the CT scanner's rotation, and less sensitivity to the patient's position relative to the radar sensor. We used human and phantom tests to show that the radar-based approach compared favorably to the state of the art. Since the method is easy to use, it is of interest for clinical PET/CT.