Revolutionary radiation: cancer killed; other cells ok

A cancer treatment that precisely maps affected tissue and directs the cancer-killing radiation while protecting the rest of the body is more than Rock Mackie's dream. It is his reality.

A professor of BME, human oncology and medical physics, Mackie has developed a software program that gives doctors more control over the radiation doses their patients receive. The program locks in the coordinates of the disease, calculates the radiation dosage and maps each radiation beam's destination. "If you had a physicist calculating this on a piece of paper," says UW-Madison oncologist Minesh Mehta, "it would take weeks, rather than minutes."

Mackie's prototype tomotherapy unit will precisely target cancer cells with its radiation. (33K JPG)

With Mehta, Mackie and a team of computer scientists refined and perfected the software program. Called Pinnacle, it melds two medical imaging technologies, computed tomography and magnetic resonance imaging. It works on diseases besides cancer and helps doctors treat about 1,000 patients a year at UW-Madison.

"We wanted to take the art and turn it into science," Mackie says. "We tried to make radiation treatments less skill-dependent and more reliant on technology."

Mackie and staff members Cam Sanders, Mark Gehring and Paul Reckwerdt also pursued Pinnacle's commercial potential, which led to several patents; the local spin-off company, Geometrics; and use in hundreds of radiation-therapy clinics nationwide. Mackie estimates it helps about 100,000 patients annually.

Mackie's latest invention also results from his collaboration with Mehta. Called tomotherapy, it can kill cancer, yet protect the cells around it, by delivering hundreds of beams of radiation in an exact dosage.

The development is a 180-degree change in how radiation is administered. Unlike conventional cancer treatments, which rely on a uniform radiation beam, tomotherapy provides a doctor with hundreds of safe coordinates to deliver radiation. The beams bombard the target, but the surrounding tissue receives considerably less harmful amounts of radiation.

Scientists at the university's Physical Sciences Laboratory (PSL) are building a prototype machine from scratch. With previous partner Redkwerdt, Mackie founded TomoTherapy Inc. Its goal is to bring the device to the medical marketplace.

The radiology field is warming to tomotherapy's potential. It may eliminate some side effects from radiation exposure and treat tumors more quickly. It may enable doctors to treat cancers that have no cure, such as pancreatic cancer, which is the nation's fifth-leading killer because so many sensitive organs surround the pancreas, rendering it impossible to treat. Treatments for prostate, liver and cervical cancers, also perilously located in the body, should improve as well.

"In the future, tomotherapy is likely to become the focal point of our radiation program at UW Hospital," says Mehta.

The hospital will begin the nation's first tomotherapy trials in 2000.