Non-contact measurement of respiratory and heart rates using a CMOS camera-equipped infrared camera for prompt infection screening at airport quarantine stations

Abstract

Severe acute respiratory syndrome (SARS) was first reported in 2003 and quickly spread around the world. Therefore, many international airport quarantine stations launched fever-based screening to detect infected passengers using infrared (IR) cameras for preventing global pandemics. However, a screening method based on fever alone can be insufficient for detecting infected individuals because many factors, such as antipyretics uptake, can affect it. Our previous studies using compact radar revealed that simultaneous measurement of facial skin temperature and respiratory and heart rates drastically improved the sensitivity of infection screening compared to that achieved by facial skin temperature measurement alone. Using a CMOS camera-equipped IR camera (CMOS-IR camera), which most Japanese International Airports have adopted, we developed an enhanced thermal/RGB image processing method for non-contact measurement of facial skin temperature, and respiratory and heart rates. We conducted the image processing on the thermal/RGB image-fusion mode in real time; we determined the respiratory rate by thermal images of the IR camera and the heart rate by the RGB images of the CMOS camera. Using a CMOS-IR camera, we measured respiratory and heart rates of ten healthy subjects (23 ± 1 years), and compared them with those determined by a contact-type respiratory effort belt and electrocardiograms (ECGs) as references. The respiratory and heart rates obtained from the CMOS-IR camera exhibited strong positive correlations with those derived from the references, a respiratory effort belt: r = 0.99, p < 0.01; ECG: r = 0.96, p < 0.01, whereas the axillary temperature indicated a moderate degree of correlation to facial skin temperature (r = 0.6). Adopting this method into conventional CMOS-IR camera image processing at international airport quarantines will achieve higher infection screening sensitivity.