To generate these values accurately, the light from the LEDs is modulated spatially, imparting distinct patterns with a digital micro-mirror device within the instrument. Formally, this functional imaging technique is called Spatial Frequency Domain Imaging, or SFDI.

"Since we use several wavelengths of light, we perform spectroscopy and obtain the content of melanin, tissue hemoglobin, in the de-oxygenated and oxygenated state, from which we can calculate the total blood volume and oxygen saturation in the tissue," Leproux said. "We measure superficially, about three to five millimeters deep."


This non-invasive look at just those few millimeters can reveal a lot about the changes radiation induces. Also, because they use a projector technology, they measure over large areas (about 20 cm by 20 cm) without scanning.

"We're hoping that we can see skin thickening in the scattering parameters we're looking at," she said. "We think that the radiation induces a remodeling of the collagen in the skin, which should be seen as a change in the scattering parameter."

The group did address concerns raised by physicians that the imaging itself exposes the skin to additional radiation, and calculated how their low power device compares to sun exposure. "Ten measurements with our device roughly corresponds to two seconds in the sun," Leproux said.

Although results are still in their infancy, they show great potential, successfully identifying distinctly different trends in melanin and oxygen saturation over the treatment time.

Along with aiming to one day predict a patient's reactions to radiation therapy, the group hopes to optimize the device in other ways along the way, perhaps helping to guide the development of better lotions to treat these side effects as well as shrinking the size of the instrument itself.

"We could optimize the current instrument in order to have shorter measurements with a cheaper device. That's something we'll look into," said Leproux.

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