Treating Cancer with Light

New LED Device May Help Advance Photodynamic Therapy for Skin Cancer. Scientists at the University of California, Irvine (UC Irvine), believe so. They're exploring new ways to image cancerous lesions using LEDs that might advance a technique for treating cancer called photodynamic therapy (PDT) -- work that they will describe at the Optical Society’s (OSA) 94th annual meeting, Frontiers in Optics (FiO) 2010  at the Rochester Riverside Convention Center in Rochester, N.Y., from Oct. 24-28.


In PDT, photosensitizing chemicals that absorb light are injected into a tumor, which is then exposed to light. The chemicals generate oxygen radicals from the light energy, destroying the cancer cells. PDT is currently approved by the U.S. Food and Drug Administration (FDA) for the treatment of esophageal and lung cancer.

Rolf Saager, who works in the lab of Anthony Durkin at the Beckman Laser Institute at UC Irvine in collaboration with Kristen Kelly, M.D., and Modulated Imaging Inc., believes that PDT could also be used to treat skin cancer. But one obstacle to this application is the lack of a detailed imaging technique to target and monitor the effectiveness of PDT.

Exploiting a technique known as spatial frequency domain imaging, the team has designed a new device with an array of five different colors of LEDs that illuminates skin with distinct intensity patterns. These patterns can change depending on the structure of the tissue and the pigments in the skin. With appropriate models of light propagation, the resulting images reveal the biochemistry of the tissue.

"Through this imaging modality, it is now possible to assess how the therapeutic light will travel throughout the affected tissue, quantify the drug present within the lesion and monitor its efficacy during treatment," says Saager.

To evaluate this spatial frequency domain imaging system, the scientists imaged a small population of skin cancers prior to treatment to characterize the variability among subjects and within the lesions themselves. The process took 5-10 seconds and produced images with a resolution of 30 microns, revealing spatially resolved maps of the optical properties of the lesions, tissue oxygenation and quantitative distribution of the photosensitizing drug.

Saager and colleagues hope that this imaging technique will provide a better map for targeting and optimizing photodynamic therapy for basal cell carcinoma, the most common type of skin cancer. The next step for their ongoing experiment will be to enable the therapeutic aspects of the instrument and monitor the tissue dynamics during PDT treatment regimens.

he talk, "A LED Based Spatial Frequency Domain Imaging System for Optimization of Photodynamic Therapy of Basal Cell Carcinoma (BCC)" is at 2 p.m. Tuesday, Oct. 26.

About the Meeting

Frontiers in Optics 2010 is OSA’s 94th Annual Meeting and is being held together with Laser Science XXVI, the annual meeting of the American Physical Society (APS) Division of Laser Science (DLS). The two meetings unite the OSA and APS communities for five days of quality, cutting-edge presentations, fascinating invited speakers and a variety of special events spanning a broad range of topics in physics, biology and chemistry. FiO 2010 will also offer a number of Short Courses designed to increase participants’ knowledge of a specific subject while offering the experience of insightful teachers. An exhibit floor featuring leading optics companies will further enhance the meeting.

About OSA

Uniting more than 106,000 professionals from 134 countries, the Optical Society (OSA) brings together the global optics community through its programs and initiatives. Since 1916 OSA has worked to advance the common interests of the field, providing educational resources to the scientists, engineers and business leaders who work in the field by promoting the science of light and the advanced technologies made possible by optics and photonics. OSA publications, events, technical groups and programs foster optics knowledge and scientific collaboration among all those with an interest in optics and photonics. For more information, visit www.osa.org.