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1. Collateral damage, in military jargon, refers to unintended carnage that is a consequence of waging war. At Vanderbilt biomedical engineers are attacking the problem of “collateral damage” that results from battling disease. Their goal is to make medical procedures free of side effects. New technology-guided therapy, the result of collaborations between biomedical engineers and surgeons, is helping medical practitioners wage war on diseased tissue while leaving healthy tissue and organs intact. In brain surgery a small error can cause a lot of unintended damage. CAT scans reveal the blueprint of the brain, but surgeons may have difficulty locating exactly—the operative word—how the specific site in the brain relates to the scan. Robert Galloway, professor of biomedical engineering, surgery and neurosurgery, has perfected a device that helps neurosurgeons “see” what they are doing, using optical techniques to track the position of surgical tools on the CAT scan or MRI. On the operating room wall, an optical device “finds” the tool in space and then relates the tool to images of the patient’s brain. The brain is located using four inserts in the patient’s skull, placed by the surgeon. Using those four points, software developed by Galloway’s team rotates the CAT scan on the screen and shows its relationship—within millimeters—to the surgeon’s tool. Surgeons guide themselves by looking on the screen, at the patient or both. A cancerous tumor looks very similar to brain tissue, so the scan is used to define the edges of the tumor. Many other cerebral procedures require great precision, as in treatment for Parkinson’s disease in which a neurostimulator is placed at a specific node in the brain. “The human eye can see in maybe two and a quarter dimensions—length, width, and a little bit of depth,” says Galloway.“But it can’t see [through tissue to] the back of someone’s head, and brain tissue is opaque. This device lets the surgeon know what’s underneath.” Anita Mahadevan-Jansen, assistant professor of biomedical engineering, is also advancing the tools available to aid cancer surgery. She has developed a probe that will perform a tissue biopsy on the fly. Her device uses two light sources, each delivered to the area under study by a slender fiber-optic probe. The first uses broadband white light reflected out of the tissue in a scatter pattern that is read by an optical device. The second uses a nitrogen laser, which causes certain molecules in the body to fluoresce.“We use the reflectance data from the white light to account for blood and the fluorescence data to give us a sense of the biochemistry and morphology of the tissue,” she says. The tissues are analyzed by comparing the reflection/scattering pattern of a given tissue with known patterns of normal and cancerous tissue.“The optical surgical guidance system we’ve developed has achieved nearly 100 percent accuracy in identifying the margins of brain tumors,” says MahadevanJansen.“Several times our techniques indicated that the surgeon had not quite gotten the entire tumor, and the histological results of the laboratory proved that the optical data were correct.” Unlike brain tumors, the cervix and ovaries have healthy tissue, cancerous tissue, and tissue that is in-between. Mahadevan-Jansen uses a different optical technique to diagnose