(PHILADELPHIA) While one of the Holy Grails in radiation oncology is to spare as much healthy tissue as possible during therapy, patients undergoing treatment for weeks at a time physically change. Patients can lose weight during a period of therapy. They might lose or gain fluid. Tumors may shrink or unfortunately, continue to grow. As a result, radiation target sites change, which can be problematic for treatment.
Thomas Jefferson University Hospital in Philadelphia and the Kimmel Cancer Center at Jefferson are among the first centers in the nation to study the effect of incorporating a new technology cone beam CT into a source of radiation, namely a linear accelerator, in an attempt to find an answer to this vexing problem.
The technology creates three-dimensional axial CT slices of a patient's tumor, enabling therapists and doctors to compare these images with initial treatment planning images to determine how precisely focused the radiation set-up is. They can then make position adjustments if necessary to deliver a more targeted therapy to the patient. The hope is that this technology will lead to more highly customized radiation treatments, where higher doses are directed at the tumor while sparing the patient's normal body structures.
"Right now, cone beam is used as one additional means of verifying the accuracy of the radiation treatments that we deliver," says Mitchell Machtay, M.D., the Walter J. Curran Jr., M.D., associate professor of radiation oncology at Jefferson Medical College of Thomas Jefferson University and vice chair of the Department of Radiation Oncology. Traditionally, patients are positioned for their daily radiation treatment by making marks on their skin, based on earlier tests, Dr. Machtay explains. "Once that is done, unless dramatic changes are seen, it's hoped that those marks will hold up for two or three or six weeks of radiation and that the treatment will be given accura