EVERY year, about 1.25 million people in the United States are diagnosed with life-threatening forms of cancer. About 60% of these patients are treated with radiation; half of them are considered curable because their tumors are localized and susceptible to radiation. Yet, despite the use of the best radiation therapy methods available, about one-third of these "curable" patients-nearly 120,000 people each year-die with primary tumors still active at the original site.![]() ![]() ![]()
PEREGRINE Breakthrough
Better Treatment Strategies |
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Radiation Therapy
Radiation has been used to treat cancer for almost 100 years. However, in most cases, a radiation dose sufficient to kill a tumor may also injure or damage nearby vital tissues or organs. Successful therapy thus depends on choosing the right type of radiation and applying the right amounts to the right places.
Today, tumors usually are treated by beams of particles from a particle accelerator, a process known as teletherapy, which is performed with any of four types of radiation. Photon or electron beams are the most frequently used, while therapies using neutrons or heavy charged particles such as protons are largely experimental. Occasionally, treatment may derive from a radioactive source that is planted inside the body, a treatment known as brachytherapy.
Photon beam energies are high enough for them to be considered x rays. They have moderate to long ranges (tens of centimeters), so they can be used for internal tumors. Photon therapy accounts for about 90% of all radiation treatments in this country.
About 10% of cancer patients receive electron therapy. Electron beams are useful for shallow cancers because electrons have limited penetrating power. Electron treatment spares deeper-lying tissues but is not effective for internal tumors.
High-energy proton beams can be designed to deposit most of their energy at one predictable depth or range. By controlling the beam energy, oncologists can control their range. A planner can tailor a proton beam to deliver most of its radiation dose into the tumor while avoiding healthy surrounding tissue. Unfortunately, proton therapy is very expensive and is available at only two centers in the U.S.
Neutron radiation has the advantage of being more effective than photons for treating some types of radiation-resistant tumors. But neutron treatment is also very damaging to healthy tissue. Experimental treatment is available at just 20 centers worldwide.
New radiation therapies are being developed to treat highly invasive tumors and cancer that has already metastasized. In experimental boron neutron-capture therapy, neutron-absorbing boron is injected into the body where it is absorbed by cancerous cells. When the body is irradiated by neutrons, the neutrons are preferentially absorbed by the boron in the tumors and the tumors are destroyed. Radio-immunotherapy, another approach under study by the research community, uses the chemistry of the body's immune system to target radioactive compounds at metastasized cancerous tumors.
PEREGRINE is now being used in research on photon, electron, proton, and neutron treatment at several leading hospitals across the country. Plans for research with PEREGRINE in the next year include collaborations on boron neutron-capture therapy, brachytherapy, and other advanced methods.
PEREGRINE in Action
Treatment Definition |
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Monte Carlo All-Particle Tracker![]() ![]() |
Supercomputer to Desktop![]() ![]() ![]()
Clinical Verification |
MEDPAC Advisory Committee
Livermore has depended on the medical community for input in developing PEREGRINE. In addition to Lawrence Livermore, hospitals and organizations represented on the MEDPAC include:
University of Wisconsin Medical School Massachusetts General Hospital Harvard Medical School M.D. Anderson Cancer Center Gershenson Radiation Oncology Center, Harper Hospital, Detroit Loma Linda University Medical Center Memorial Sloan Kettering Cancer Center Washington University University of California, San Francisco Université Catholique de Louvain, Brussels, Belgium Los Alamos National Laboratory
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A Look Ahead![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
Key Words: cancer treatment, Monte Carlo physics, nuclear databases, radiation dose calculations, radiation therapy, tumors.
For further information contact Edward Moses (510) 423-9624 (moses1@llnl.gov), Christine Siantar (510) 422-4619 (hartmannsiantar1@llnl.gov), or the PEREGRINE website (http://www-phys.llnl.gov/peregrine/).
EDWARD MOSES, PEREGRINE program leader since 1994, received a Ph.D. (1977) in electrical engineering from Cornell University, where he specialized in quantum electronics. His earlier Lawrence Livermore experience includes program manager of the AVLIS (Atomic Vapor Laser Isotope Separation) Program from 1986 to 1990.
CHRISTINE SIANTAR, principal investigator of the PEREGRINE program, received her Ph.D. (1991) in medical physics from the University of Wisconsin. Prior to joining Lawrence Livermore in 1994, she gained experience in cancer treatment planning at the Medical College of Wisconsin. Her present duties also include validation and verification of the Monte Carlo calculations for PEREGRINE.