New skin cancer probe could expand access to a prompt diagnosis

Skin cancer is one of the most common types of cancer in Canada, with 80,000 people diagnosed every year. Although these rates are rising, skin cancer is one of the most curable types of cancer if it is detected early.

Daniel Louie and Dr. Tim Lee, researchers at UBC working with BC Cancer and the Vancouver Coastal Health Research Institute, have recently published a paper in the Journal of Biomedical Optics detailing a new low-cost laser probe for early skin cancer detection. Louie — who is pursuing a PhD in biomedical engineering — explained that “in order to screen a large volume of this disease, then we need more widely accessible technologies.” This optical probe uses principles of light polarization to differentiate cancerous cells from normal cells.

Light waves coming from the sun or your phone screen all have a certain orientation as they travel through space. This orientation is called the polarization of light. When a source produces light waves all neatly ordered in the same orientation, this light is said to be polarized. Light can be depolarized by hitting an object and scattering every which way.

Because cancer cells are often large and irregularly shaped, they scatter light with a different polarization pattern than regular cells. This polarization pattern is referred to as polarization speckle by the researchers. By shining a laser with a known polarization of light at suspected cancerous cells, these researchers are able to make a diagnosis by analyzing the depolarization of the scattered light. This principle allows for a low-cost diagnostic device with relatively cheap and simple optical components.

Lee has been working on the idea to use polarization speckle for skin cancer screening for about ten years, but Louie began working on the probe four years ago. In order to make the device as accurate and simple as possible, the team developed a new kind of detector to analyze the depolarized light. As Louie explained: “This device can measure the polarization state in a snapshot, and that is relatively new.”

“Measuring polarization state, you normally need four measurements, and the most common way to do that is to use sophisticated optics [to] actuate using electricity and motors to change a filter four times in rapid succession so you divide your measurements by time,” said Louie. “But that increases the measurement time, and it's not very friendly to something in vivo like something that can be used in a clinic.” The new device will instead use four detectors separated in space to take four separate measurements all at once. Using statistical analysis, Louie is then able to process the polarization speckle of the scattered light.

The team hopes to begin larger clinical trials to assess the accuracy of the optical probe and begin commercializing their research project so that it can be used by dermatologists. “We're still in [the] experimental stage right now,” said Louie. “In order to actually determine the accuracy we need to do a much larger clinical trial first, so much more research has to be done, but we hope that we will be able to bring this device further along into making a significant impact in the future.”

By engineering innovative solutions, the team has been able to simplify the diagnostic tool and make it cheaper and, eventually, more accessible to dermatologists. Louie believes that this trend in biomedical engineering is helping to lower the cost of healthcare and democratize access to promising new technologies.

“The principle of trying to innovate using low-cost parts instead of just increasing the budget [for] pre-existing techniques and refining them even further, I think that's a design philosophy that we can apply to more practices in biomedical engineering, if you make something work with a lower cost, and make it accessible to more things, you can make healthcare in general more accessible,” he said.