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Zapping Cancer with New Neutron-Based Therapies Researchers are developing more effective radiation methods. by T.J. BECKER | |
THE BATTLE IN radiation therapy has always been about minimizing damage to normal tissue, says Chris Wang, an associate professor in Georgia Tech’s School of Mechanical Engineering, who is developing new neutron-based methods for treating cancer.
Associate Professor Chris Wang and his collaborators are developing a new generation source of neutrons for neutron brachytherapy, a type of radiation treatment for cancer. The smaller neutron source delivers radiation more uniformly inside a tumor.
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Traditional radiation treatment uses gamma rays or X-rays. Yet neutrons can be more effective because they deposit more concentrated energy at the subcellular level.
“But the damage neutrons cause is more difficult for cells to repair,” Wang says. “That’s good for the cancer cells, but bad for surrounding normal tissue.”
In fast neutron therapy (FNT), patients are treated with an external beam of high-energy neutrons produced by a particle accelerator. The neutron energy destroys the tumor, but there’s a “late effect” in that normal tissue may deteriorate within a few months, Wang explains. Thus, FNT can only be used for certain cancers, such as salivary gland cancer.
A more promising method is neutron brachytherapy (NBT) where patients receive neutrons via the insertion of a sealed, miniature, neutron-emitting isotope. Because NBT uses an internal delivery method, radiation is more concentrated in the tumor area and poses less risk to normal tissues.
Yet adoption of NBT has been limited because existing neutron sources are too large and weak to be distributed evenly throughout a tumor.
Wang has been collaborating with the U.S. Department of Energy’s Oak Ridge National Laboratory and Isotron Inc., an Alpharetta, Ga.-based start-up company, to develop a new generation source of neutrons for NBT. In a recent advance, the researchers have encapsulated a neutron source that is 20 times smaller in volume and five times stronger in intensity.
The new Cf-252 neutron source, left, under development by Georgia Tech and other researchers is 20 times smaller in volume and five times stronger in intensity than older neutron sources, right, used in radiation therapy for cancer.
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“The smaller the neutron source, the better, because it can be administered more uniformly inside the tumor,” Wang says. He is developing the delivery system for NBT, and clinical trials are about a year away.
With funding from the Georgia Cancer Coalition, Wang is also studying a new group of chemical compounds for treating prostate cancer. The disease is often treated with neutron capture therapy (NCT). A patient is first injected with a neutron-sensitive compound that targets cancer cells; then an external beam of low-energy neutrons irradiates the tumor.
Though promising, NCT’s success relies on having the ideal compound. “If you miss some of the tumor cells, it won’t be effective,” Wang says. “And the biological pathways of a human body are too complex for this to occur.”
With this in mind, Wang is working on a new approach that he calls “boron-enhanced neutron brachytherapy” – a combination of NBT and NCT. The idea is to administer boron, a neutron-capture agent, to target tumor cells before the neutron-emitting isotope is inserted.
“In this case you wouldn’t need a perfect compound,” Wang explains. “The compound would act as an enhancement as opposed to relying completely on it.”
courtesy of Chris Wang
courtesy of Chris Wang
For more information, contact Chris Wang at 404-894-3727 or
chris.wang@nre.gatech.edu.
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Last updated: July 7, 2004
