Patients have a new treatment option for brain tumors. The Gamma Knife Model C at Saint Joseph's Hospital in Marshfield is just the third of its kind in the world and the first in Wisconsin.

The Knife, not really a knife at all, is a non-invasive treatment for brain abnormalities. It allows physicians to treat areas of the brain that could not be reached otherwise and provides an alternative to conventional neurosurgery, said Warren Olds, M.D., Medical Director of Radiation Oncology at Marshfield Clinic-Marshfield Center. For example, tumors in the brain stem, now treated with the Gamma Knife, could not be reached before because brain stem tissue cannot be removed surgically, Dr. Olds said.

The Gamma Knife Model C, using magnetic resonance images to show the tumor location, passes radiation through normal tissue to the abnormal area in the brain. The results are "very effective," Dr. Olds said.

The Gamma Knife looks like 20 tons of space-age technology and the patient, encased in the helmet-like device, might just look a bit like a spaceman. Technology sending gamma rays to affected areas is not new, but recent refinements in imaging make it more effective. "It's a technology leapfrog," Dr. Olds said. "What's new is that, because we're using the MRI in conjunction with the Gamma Knife, we're able to see lesions better than ever before and plan accordingly."

Precision is the benefit of the Gamma Knife, Dr. Olds said. The tumor is hit with radiation but tissue around the tumor is left unharmed. Changing the size of the 201 holes that allow the radiation into the brain means the machine can be used on oddly shaped tumors. Dr. Olds compared this technique with filling a curved bottle with tiny stones. If the stones are small enough, you can completely fill the edges and curves of the bottle. Similarly, minute adjustments are made in the duration and size of rays to completely treat the abnormality.