From Tumor Targeting to Speech Monitoring: Accurate Respiratory Monitoring Using Medical Continuous-Wave Radar Sensors

Since the debut of medical radar sensors nearly four decades ago, there have been many technical advancements that helped this technology mature. Progresses have been seen from system architectures to signal processing algorithms. Many research efforts have been dedicated to utilize the radar sensors for different biomedical applications such as noncontact vital sign detection, human fall detection, through-wall detection, and medical imaging. A special application is radar respiration measurement in motion-adaptive cancer radiotherapy. The radar measures the respiration pattern that is used to infer the tumor location in real time. To realize accurate respiration pattern measurement, the signal distortion problem in a conventional CW radar sensor was extensively analyzed, and the solution led to a dc-coupled radar that is distortion-free. Successful preliminary clinical tests have been carried out using the radar sensor in a radiotherapy environment, demonstrating its feasibility. The same dc-coupled physiological radar sensor solution also shows the potential of monitoring the physical states and speech of the subject person.