2748 - Clinical Evaluation of Joint Respiratory and Cardiac Phase Binning 4DCT Based on mmWave Signals

Purpose/Objective(s): Cardiac radioablation requires accurate imaging of targets affected by both respiratory and cardiac motion. Conventional clinical CT or linear accelerator motion management systems can only monitor either respiratory or cardiac motion at a time, limiting the ability to resolve complex asynchronous displacement. This study validated the use of non-contact mmWave sensing for joint respiratory and cardiac phase binning in 4DCT using a completed patient cohort.

Materials/Methods: Ten patients undergoing lung cancer simulation were imaged with standard respiratory 4DCT. A gantry-mounted mmWave radar sensor concurrently acquired surface motion signals without patient contact. Respiratory and cardiac waveforms were extracted using signal processing algorithms, and novel joint phase binning algorithms were developed to reconstruct dual-gated 4DCT volumes. Agreement between mmWave-derived respiratory rates and CT-based measurements was quantified.

Results: The study cohort of 10 lung cancer patients (median age 71.5 years, range 40-79, 70% female and 30% male). The mean respiratory period measured by mmWave and CT motion sensors differed by 1.16% (±1.78%). Dual-phase 4DCT reconstruction was successful in 9 patients (90%) with no significant motion artifacts. Patient BMI ranged from 18.83 to 42.35, with failure occurring in the patient with a BMI of 42.35.

Conclusion: This study shows that non-contact mmWave sensing enables reliable joint respiratory and cardiac phase binning for 4DCT, with successful dual-phase reconstruction in 90% of cases. The high agreement between mmWave- and CT-derived respiratory rates confirms the approach's accuracy. This technology can overcome limitations of conventional systems by simultaneously monitoring respiratory and cardiac activity, improving motion-resolved imaging for cardiac radioablation planning and gated treatment delivery.