http://www.laserfocusworld.com/articles/print/volume-50/issue-09/newsbreaks/terahertz-reflectometry-identifies-early-skin-cancer.html

Terahertz reflectometry identifies early

skin cancer 09/03/2014

By Gail Overton

Senior Editor

Applied Research & Photonics (ARP; Harrisburg, PA) is applying its terahertz-reflectometry

systems—which have also been used for multilayer paint-thickness analysis and fault

detection in silicon chips—to the identification of early-stage skin cancer. In the experimental

setup, both benign and basal cell carcinoma (BCC) skin samples are analyzed using terahertz

reflectometry, terahertz time-domain spectroscopy, and terahertz imaging. The electro-optic

dendrimer (EOD)-based continuous-wave (CW) terahertz source—which emits broadband

energy from 0.1 THz to approximately 35 THz—exploits a mechanism invented by ARP called

dendrimer dipole excitation (DDE). This mechanism stems from the fact that the EOD has a high

electro-optic coefficient (around 130 pm/V) and thus offers high conversion efficiency.

The terahertz source is reflected off the highly layered structure of human skin and the layering

information is obtained by subtracting the reflected intensity data from the baseline (empty cell)

data. Data analysis reveals that healthy skin is evenly layered while the layering pattern of

cancerous cells is significantly diminished, indicating cell agglomeration and/or tumor

formation. Measurements with an ARP TeraSpectra spectrometer confirm that healthy skin

produces a terahertz spectrum that is different than diseased skin. A reconstructive-imaging

algorithm is used to create 3D skin images that confirm healthy skin exhibits a regular cellular

pattern while the cancerous tissue is amorphous. The noninvasive technique could eliminate the

need for biopsy as the main mode of skin-cancer diagnosis. Contact Anis Rahman

at a.rahman@arphotonics.net.