University of Minnesota Medical Center, Fairview marked a medical milestone recently when it performed the world's first head-to-foot, total marrow irradiation (TMI) using TomoTherapyTM technology.
Using TomoTherapy, physicians now are able to direct radiation precisely to the bone marrow, sparing critical organs and reducing the incidence of side effects. And because radiation is directed to the marrow, patients may be able to receive higher doses of radiation. The reason for selectively irradiating the bone marrow is that this is where cancer cells that contribute to relapse are thought to be.
"TomoTherapy makes it possible for us to target cancer cells in the marrow with a higher dose of radiation and fewer complications," says Kathryn Dusenbery, MD, radiation oncologist and chair of the department of therapeutic radiation at the University of Minnesota.
TMI is performed at a few other cancer centers in the United States, but this is the first TMI procedure to deliver radiation to bone marrow over the entire body, from head to foot, says Susanta Hui, PhD, assistant professor of therapeutic radiology, University of Minnesota.
Total body irradiation (TBI) is widely used prior to transplant as part of the conditioning regimen for BMT. However, TBI delivers radiation to the whole body and can result in damage to unaffected organs, such as the lungs, heart, brain, kidneys and eyes. In contrast, using TMI, the radiation is focused more on the areas of cancer involvement, such as the bone marrow, resulting in either fewer side effects or higher doses of radiation delivered to patients.
"The standard had always been total body irradiation," says Hui. "TomoTherapy makes it possible to precisely target bone marrow."
TomoTherapy provides three-dimensional imaging immediately prior to each treatment to verify the location of a patient's tumor. Radiation is delivered by a beam from any point in a 360-degree radius around the patient, reducing exposure of healthy tissue to radiation and decreasing side effects for patients for more accurate and precise treatment of the tumor.
Hui, Dusenbery and Michael Verneris, MD, assistant professor of pediatrics, blood and marrow transplantation, collaborated for the past two years to make the radiation treatment method possible. Researchers are conducting a dose escalation study to determine whether this approach is tolerated with the ultimate goal of reducing disease relapse. Their research will continue, giving them a better understanding of radiobiological issues and the ability to implement further clinical applications that benefit patients.
