UC Berkeley nuclear engineers are developing a new weapon in the fight against cancer. The treatment, Boron Neutron Capture Therapy, integrates computer simulation with a portable and inexpensive beam generator to target tumors without causing the collateral damage of traditional X ray and gamma ray radiation therapy.
"If it works, a patient may only need one 30-minute treatment instead of many over the course of several weeks," says associate professor of engineering Jasmina Vujic, whose research has already yielded encouraging results in simulated treatments of deadly brain tumors.
The problem with using gamma or X rays to kill cancer is that the radiation is not choosy about its targets. As Vujic says, "the gamma rays may kill healthy cells as effectively and easily as tumor cells."
With Boron Neutron Capture Therapy, the patient is injected with a drug containing antibodies that seek out cancer. The antibodies act as a transport for other chemicals as well, tags that highlight the cancer so itís easily distinguishable from other cells. In this case, the tagging chemical is boron, which absorbs cancer-killing neutrons fired from the beam generator.
"It's like you're coloring that particular location in red,"
Vujic says. "The boron says 'I'm the target.' Now it's visible
to neutrons and they will mostly go to that location," destroying
the cancer thatís there.
While physicians and biologists continue development of the most safe and effective boron-carrying drug, Vujic and her colleagues are focused on engineering and optimizing the radiation source.
"You could use a nuclear reactor to generate neutrons, but you obviously can't put one in the basement of every hospital," Vujic says.
In today's hospitals, gamma and X rays are generated by multi-million
dollar linear accelerators -- 15 foot behemoths that weigh upwards
of 30,000 pounds. Similar to compact commercial nuclear devices
lowered into bore holes to locate oil, the fusion generator Vujic
is designing with Lawrence Berkeley National Laboratory senior
staff scientist Ka-Ngo Leung and his research group is approximately
three feet long and expected to cost an estimated $300,000 to
$500,000. Plans are underway to build a prototype of this portable
neutron generator in the campusí nuclear engineering research
facility.
Once the neutron generator is complete, the fine-tuning begins. For each individual patient, the beam must be massaged to an optimal power and intensity to provide the maximum benefit while minimizing the potential for damage to healthy cells. The optimal shape of the beam depends on the depth and size of the tumor while the intensity of the beam determines the length of the therapy.
Courtesy Lawrence Berkeley National Laboratory
While
traditional linear accelerators require custom high-power
electrical supplies, this suitcase-size neutron source runs
on the same "off-the-shelf" power supply as a
standard X-ray machine.
(Click for larger image.)
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"We start by using multiple imaging technologies ‚ CAT and PET scans, for example ‚ to describe the body in mathematical terms," she says.
That digital representation of the body is then combined with simulations
of the neutron generation process to determine the optimal settings
for the beam and the specifics of where it should be aimed and
for how long. Higher-resolution medical imaging technologies,
currently under development by UC Berkeley's Department of Nuclear
Engineering, would further aid the optimization process, Vujic
says.
To hammer out various treatment methodologies, Vujic and her colleagues consult massively parallel supercomputers running complex software. Lawrence Livermore National Laboratory has led the pack in the development of this cancer treatment planning software and Vujic's group is collaborating with a team there, led by Christine L. Hartmann-Siantar, on further program enhancements.
"The goal is to have patient-specific optimization," she says. "The physician
could plug the patient's data into a computer simulation and in
about two hours he would get the most optimal treatment plan including
how to shuffle the neutron source and beam, where to place the
patient, and how long the treatment will last."
According to Vujic, Boron Neutron Capture Therapy could also be beneficial in treating breast cancer. Her group is currently seeking funding to explore this area, along with other medical conditions including rheumatoid arthritis and skin cancer.
"These problems are all too complex for just a biologist or physician to solve," Vujic says. "You need physicists, chemists, and engineers too, all working on different aspects of this."
Professor Jasmina Vujic's home page
Boron
Neutron Capture Therapy at LBL
Conference on Environmental Recovery of Yugoslavia
