World first for non-contact respiratory motion monitoring

Monitoring respiratory motion during diagnostic imaging and radiation therapy is necessary for accurate diagnosis and treatment. However, respiratory motion is rarely monitored during these procedures due to the lack of practical, non-invasive tools.

The MWS sensor solution to this issue is a non-contact device that uses electromagnetic radiation to detect motion in various scenarios. Unlike traditional systems, such as infrared sensors that require the use of reflective markers on the patient’s body, the MWS works without any physical contact. Their findings are detailed online in Medical Physics.

To validate the effectiveness of the MWS, the researchers led by Dr Hiroyuki Kosaka, along with Dr Kenji Matsumoto and Dr Hajime Monzen from the Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, utilised a 24GHz microMWS for detecting the respiratory motion.

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“We tested the system using a controlled respiratory motion phantom [QUASAR]. This phantom allowed us to simulate respiratory motion under controlled conditions, comparing the MWS’s ability to detect subtle changes in motion with the phantom’s known motion patterns,” Dr Kosaka said in a statement.

The MWS is reported to have successfully detected the motion patterns, ensuring it could reliably capture respiratory cycles even in controlled test scenarios.

The research team validated the system through extensive testing, including trials with 20 healthy volunteers ranging from six months to 64 years of age.

Key advantages of the new system include non-contact monitoring that maintains patient privacy and comfort, accurate detection through clothing, stable measurements in prostrate and standing positions, cost-effective implementation compared to existing technologies, and easy integration with current X-ray and CT equipment.

“This technology has the potential to standardise respiratory monitoring across diagnostic imaging," said Professor Monzen. "By providing objective, real-time feedback, we can significantly reduce the need for repeat imaging and improve diagnostic accuracy.”

To test how well the MWS could detect movement, the team used a radio-wave dark-box system, which helped determine the sensor’s directionality. This test measured how accurately the MWS could detect motion from different angles. The researchers also optimised the sensor to pick up specific frequencies of movement using fast Fourier transform, which helps identify and separate the relevant breathing signals.

To ensure the accuracy of the MWS, the team compared the detected breathing patterns with those of QUASAR. This phantom allowed the researchers to simulate breathing with different levels of motion. By comparing the waveforms from the MWS and the phantom, findings confirmed the MWS's ability to reliably track respiratory motion.

The team believes the MWS system could become a standard tool in hospitals and clinics worldwide. 

“By offering a precise, non-invasive, and cost-effective way to monitor respiratory movements, the MWS can enhance diagnostic accuracy, improve treatment outcomes, and contribute to more efficient healthcare,” said Dr Kosaka. “This breakthrough represents a major advancement in medical technology, with the potential to revolutionise how healthcare providers approach respiratory motion monitoring, improving both patient experiences and outcomes.”