Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409, USA.
IEEE Trans Biomed Eng. 2012 Nov;59(11):3117-23. doi: 10.1109/TBME.2012.2206591. Epub 2012 Jun 29.
Accurate respiration measurement is crucial in motion-adaptive cancer radiotherapy. Conventional methods for respiration measurement are undesirable because they are either invasive to the patient or do not have sufficient accuracy. In addition, measurement of external respiration signal based on conventional approaches requires close patient contact to the physical device which often causes patient discomfort and undesirable motion during radiation dose delivery. In this paper, a dc-coupled continuous-wave radar sensor was presented to provide a noncontact and noninvasive approach for respiration measurement. The radar sensor was designed with dc-coupled adaptive tuning architectures that include RF coarse-tuning and baseband fine-tuning, which allows the radar sensor to precisely measure movement with stationary moment and always work with the maximum dynamic range. The accuracy of respiration measurement with the proposed radar sensor was experimentally evaluated using a physical phantom, human subject, and moving plate in a radiotherapy environment. It was shown that respiration measurement with radar sensor while the radiation beam is on is feasible and the measurement has a submillimeter accuracy when compared with a commercial respiration monitoring system which requires patient contact. The proposed radar sensor provides accurate, noninvasive, and noncontact respiration measurement and therefore has a great potential in motion-adaptive radiotherapy.
准确的呼吸测量在运动自适应癌症放射治疗中至关重要。传统的呼吸测量方法不理想，因为它们要么对患者有侵入性，要么准确性不够。此外，基于传统方法的外部呼吸信号测量需要患者与物理设备密切接触，这往往会导致患者在辐射剂量输送过程中感到不适和不希望的运动。本文提出了一种直流耦合连续波雷达传感器，为呼吸测量提供了一种非接触式、非侵入式的方法。该雷达传感器采用直流耦合自适应调谐架构设计，包括射频粗调谐和基带细调谐，使雷达传感器能够精确测量具有静止时刻的运动，并始终以最大动态范围工作。利用物理体模、人体和放射治疗环境中的移动板对所提出的雷达传感器的呼吸测量准确性进行了实验评估。结果表明，在辐射束开启的情况下，利用雷达传感器进行呼吸测量是可行的，并且与需要患者接触的商业呼吸监测系统相比，测量精度达到亚毫米级。所提出的雷达传感器提供了准确、非侵入性和非接触式的呼吸测量，因此在运动自适应放射治疗中有很大的应用潜力。
