Attacking Tumors With Miniaturized, High-Frequency Antennas

By Chuck Seegert, Ph.D.

A team at the University of Wisconsin has figured out a way to miniaturize tumor ablation antennas by delving deep into microwave physics. These smaller scale antennas could provide surgeons with treatment options previously unavailable.

Microwave tumor ablation is a method that delivers energy to tumors, essentially cooking them and killing cancer cells. Like many cancer treatments, targeting the malignant cells while sparing the healthy tissue is the goal. In order to achieve this, electromagnetic energy is focused using antennas that are inserted into the tissue. Current microwave ablation technologies are based on low frequency radiation, which requires the antennas to be relatively large. Consequently, when they are inserted, they can cause significant damage to any adjacent tissue.

By challenging certain assumptions about microwave ablation, a new approach to this treatment method is on its way to commercialization, according to a recent press release from the University of Wisconsin. The discussion was started by Joshua Medow, an assistant professor of neurosurgery, who was inspired to explore this area when one of his instructors, John A. Sandin, died of brain cancer.

"When I was talking with John, I thought there has to be a better way (to treat brain tumors) than taking somebody's head apart," Medow said in the press release.

Expressing his desires to professors of electrical and computer engineering Susan Hagness and Nader Behdad, Medow convinced them to look into microwave radiation, according to the press release.  Historically, only low frequency energy has been used, but Hagness and Behdad looked more closely at high frequency radiation. Through simulation analysis, they discovered that high frequency radiation could deliver enough energy to be effective at tumor treatment — a revelation that contradicted many assumptions previously held in this field.

In addition to finding that higher frequencies were effective, the team discovered that different resonant frequencies could deliver therapy with much smaller equipment. Existing equipment requires a component called a balun to manipulate the waves of radiation, but the new approach uses inherent wave characteristics to achieve the same thing. This eliminates the need for a balun, which opens the door for many miniaturized designs that could be threaded through the circulatory system or even a small hole in the skull.

The value of the new approach has been recognized by the National Science Foundation, and the organization has given the team a $390,000 grant to develop and design the new system, according to the press release. The team has filed patents and hopes to commercialize their miniaturized antennas in the near future.

These developments come at a propitious time for the team, as some observers feel that the field of microwave ablation is poised for significant growth.