Imaging Tools Help Target Tumors and Protect Surrounding Tissue
DURHAM, N.C. -- One of the biggest challenges in using radiation therapy to treat lung cancer is targeting the tumor. The goal is to deliver a safe, effective dose of radiation while minimizing incidental damage to surrounding, normal tissue in the lung, heart and esophagus.
"Every direction you choose, there'll always be some dose going to some of the normal tissues," explained Lawrence Marks, M.D., professor of radiation oncology at Duke University Medical Center. "The problem we've had for the past 50 years in the treatment of lung cancer is that the normal tissues in and around the chest don't tolerate the radiation that well.
"We've always been limited in how much radiation we can give," he adds, "and that's made it even more difficult to treat or cure lung cancer. What we and others have been able to do is develop tools that enable us to better understand how the normal tissue reacts to the radiation so we can better understand how to optimally deliver the radiation. It's always a trade-off. You have to deliver some dose to some normal tissue. By studying the response of the heart and lung to radiation, we have a better understanding of how much is safe to deliver."
Marks says this process has been made possible in large part by tremendous advances in imaging. He credits 3-D imaging tools such as Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) scans for helping aim the radiation more accurately to better target the tumor and reduce the risk of collateral damage. These tools, now in use at most major medical centers, have become valuable for physicians and technicians trying to isolate a tumor in the lung to receive the proper dose of radiation.
"These tools help us figure out better ways to aim the radiation, figure out which directions are most optimal, so that we can therefore minimize the damage to a patient's heart, lung or esophagus," says Marks.
"There is also a number of drugs that are being investigated that, when given to patients during their radiation, might reduce or lessen the effects of the radiation on normal tissue," Marks says. "These are currently being studied in many places."