Georgia Tech thermal imaging captures patient's vital signs in detail

02 Apr 2025

Phasor thermography method opens new possibilities for early disease detection.

A project at Georgia Tech has developed a modified thermal imaging platform better able to assess a patient's vital signs for early detection of disease or other ill health conditions.

Although thermography and the capture of infrared thermal radiation from the human body has been widely applied in healthcare research, several challenges to its clinical use still remain according to the project.

"Despite significant advancements, conventional systems encounter limitations, predominantly due to the spectral ambiguity in thermography," commented the team in its Cell Reports Physical Science paper.

"Thermal radiations originating from target objects and environmental scattering exhibit broad and overlapping emission spectra, leading to the ghosting effect where the texture details are immersed and thus imperceptible."

The team's solution involved phasor analysis, a numerical method already used for simplifying complex fluorescence lifetime data. A project at Ruhr University Bochum recently applied a phasor-based technique to the detection of contaminants in the environment.

Georgia's phasor thermography (PTG) method "leverages hyperspectral radiation modeling, full-harmonics thermal phasor analysis, and thermal unmixing to enhance texture extraction, material classification, and precise temperature measurement," said the project.

The PTG device uses a series of filters to capture 10 images of different parts of the long-wavelength infrared spectrum. With those 10 images acquired, a thermal phasor analysis mathematical tool borrowed from signal processing resolves textures in three dimensions smaller than one millimeter.

That level of detail allows fine thermal variations to be distinguished, differentiating facial skin, thick hair near the scalp, thinner hair of eyebrows, and even metal rims of eyeglasses on a human subject.

Next generation breast cancer detection technology

In trials using phantom and living subjects in room-temperature settings, the PTG platform showed fully passive and reliable detection of human vital signs such as temperature, heart rate and respiration rate from various body regions.

"We used a thermal camera and the filters to get the hyperspectral image data, so it's scalable," said Dingding Han from Georgia Tech's School of Mechanical Engineering. "You could integrate this setup into virtually any thermal imaging platform."

The hyperspectral phasor approach could also be extended to near- and mid-IR spectral regions through upconversion technology and silicon detectors, extending its applicability further. Han envisages the technology being readily suited for existing clinical workflows with minimal problems, and is working towards a prototype system suitable for spotting breast cancer tumors.

"Thermography could give us an advantage in early detection, because it could noninvasively detect abnormal cell activity that indicates early cancer," Han said. "Tumor cells need more oxygen to reproduce, so their temperature will be a little bit higher than normal tissue. With this phasor thermography approach, we could spot that. This can be the first step for the next generation of biomedical thermography, for early detection and diagnosis of cancer."