Features: Feb. 4, 2002

Terahertz Imaging Provides Advantages Over X-Rays

Terahertz-computed tomography (T-ray CT) is a new imaging process that extends beyond X-ray CT methods and has enabled Rensselaer researchers to create 3-D images of dielectric targets, including biological objects, such as cross sections of bones.

3-D image of turkey bone created through terahertz imaging

Terahertz imaging is attractive for a number of reasons: the radiation is non-ionizing and poses very few safety risks, it is capable of sub-millimeter resolution, and it provides spectroscopic information.

In biomedical application, T-ray CT could lead to enhanced imaging and diagnostic techniques for skin cancer, skin burn severity, and even tooth cavities. In industrial application, T-ray CT could be a mailroom's "eyes" in determining if there are spores in a letter, for example.

The inspiration for T-ray CT was drawn from the now ubiquitous X-ray CT method. However, terahertz CT can "see" a different spectrum range than X-ray CT, according to Xi Cheng Zhang, the J. Erik Jonsson Distinguished Professor of Science.

The technique is made possible by an earlier discovery in using a "chirped probe" that delivers picosecond-long "blasts" or "chirped pulses" of light that can accelerate the time it takes to acquire accurate images, especially in biological tissue, from hours or days, down to minutes or seconds.

"Terahertz gap is a scientifically rich but technologically unexplored frequency band," says Zhang "This terahertz frequency range presents the next frontier in imaging science and technology."