One method for treating cancer involves injecting a patient with a metal probe in close proximity of a tumor. The probe is then rapidlycooled to the point of freezing and killing the surrounding tissue. Called a cryoprobe, the technique is gaining traction in medicine, but the procedure isn’t as simple or fast as many doctors would like.
The solution for optimizing cryoprobes may not come from a medical lab, but rather, from the UW-Madison Solar Energy Lab (SEL).
SEL includes researchers who study refrigeration cycles at a variety of temperatures. Elmer R. and Janet Ambach Kaiser Chair and Mechanical Engineering Associate Professor Gregory Nellis is most directly involved with the cryoprobe project, along with Ouweneel-Bascom Mechanical Engineering Professor and SEL Director Sanford Klein and Mechanical Engineering Professor John Pfotenhauer.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provided initial funding in 2004 for SEL researchers to develop a model to design more powerful, yet small, cryoprobe systems. Ideally, probe systems would involve one probe, rather than the three or four currently used in treatment sessions, that would freeze cancer tissue so quickly the whole procedure could take around an hour and the entire system, including compressors, refrigerant fluid lines and the probe itself, would be small enough to fit in a doctor’s office.
With another ASHRAE grant, the researchers now are building an experiment to rigorously test their model and measure the performance of various cryoprobes. American Medical Systems in Minnetonka, Minnesota, provided the lab with a cryoprobe system, and PhD student Harrison Skye has worked on designing and fabricating a method to test cryoprobe efficacy. For example, changing the composition of the fluid used to cool the probe can alter its performance, and the SEL team is particularly interested in finding the optimal fluid mixture.
“This is an extremely sophisticated experiment, and I’m excited to see how the data compares to the model,” says Klein.