Features: Jan. 14, 2002

T-Rays Could Speed and Improve Diagnoses, Researchers Say
Xi-Cheng Zhang, the J. Erik Jonsson '22 Distinguished Professor of Science, and a team of researchers are the first to image tissue using single pulses of terahertz (THz or T-ray) radiation. The technique will improve diagnostic time from hours or days, down to minutes or seconds.

Zhang and his colleagues combined T-rays—those that are within the far-infrared region of the electromagnetic spectrum—with a new technique that delivers single-picosecond-long "blasts" or "chirped pulses" of light that allows the full THz spectrum to be measured. Using a single pulse of THz radiation that is only a few picoseconds long allows for better and faster imaging results in biological tissue. The techniques could one day lead to computerized medical diagnoses right in the physician's office.

The unique properties of THz radiation allow it to "see" farther, and in more detail, than imaging methods such as X-rays, ultrasound, and radar. For example, T-rays have been demonstrated to effectively image skin burn severity, tooth cavities, and skin cancer.

"Our idea is to fully automate analysis of these images," says Zhang. "One day it could lead to diagnostic tools based on the THz response."

In combination with the chirped probe, the technique offers highly detailed biological images (even if a patient moves during the procedure). The images can be layered and mapped in color to produce high-resolution images for biomedical applications.

A picture of a skin cancer tumor, for example, would be pieced together using multiple T-ray images at different angles. This method creates a biologically accurate 3-D picture that gives a researcher or diagnostician a better understanding of the disease and how far it has spread.

Important applications are foreseen not only in the medical world, but also in package inspection and manufacturing quality control.