Room: Exhibit Hall | Forum 6
Purpose: Ballistocardiogram is a technique to measure recoil forces of the body in reaction to blood ejection into vasculature and is used to assess cardiac functions. When the device is properly positioned, it can also detect respiration induced body pressure changes. We explored the potential of using such a device to accurately capture patientâ€™s breathing patterns and phases for applications in radiotherapy, for example, the sorting of 4D CT images.
Methods: The pressure-based respiration monitoring system (PBRMS) consists of a sensor belt, an analog signal processing unit and a software program. For 23 patients going through 4D CT scan using a commercial respiration management system (CRMS), the sensor belt was placed on the CT table in close contact with the patientâ€™s back in the thorax region, to measure the pressure signal in synchronization with the commercial system. The two signals were then compared with phase differences and correlations calculated. For 11 patients, 4DCT images were obtained using the respiration signals obtained from both CRMS and PBRMS. The two 4DCT series were then compared in terms of number of respiration induced CT artifacts.
Results: The respiration signal derived from PBRMS matched with those from CRMS closely when patients breathed regularly. When irregular breathing occurred, PBRMS showed larger excursions than CRMS for some patients, but vice versa for others. The number of 4D type artifacts, e.g., â€œmushroomâ€? alike, were found to be comparable between the two 4DCT series, derived based on CRMS and PBRMS, respectively.
Conclusion: We have shown that pressure based respiration monitoring system captured the patientâ€™s respiration signal sufficiently accurately and could be used for 4DCT reconstruction with comparable 4D image quality compared to a widely used commercial system. The pressure changes measured on patientâ€™s back could be a qualified surrogate of respiration.
Not Applicable / None Entered.