Ion therapy charges forward.
Medical therapy using electrically charged subatomic particles began about 30 years ago, but only in the last few years has it included the use of ions (atomic nulcei). Up to now the most used ions have been hydrogen (protons) and helium, which have been used mostly on cancers of the eye (SN:9/24/83, p.204). At the same Berkeley meeting, early reports were given on two promising extensions of the technique: the use of heavier ions than helium on tumors and the use of helium ions on certain abanormalities of blood vessels in the brain.
The new synchrotron would be called ABRA (Advanced Biophysical Research Accelerator)--please note they say, not abracadabra--and would be able to accelerate ions of all elements between helium and silicon in the periodic table, as well as argon and iron. The purpose of building it at a medical center is to shift the responsibility for patient treatment to hospital personnel, leaving the research physicians, biologists and physicists to concentrate on studying the effects of different kinds of ions on cells and tissues. The total cost of the installation will be between $74 million and $77 million. They hope for an appropriation to begin in fiscal year 1987, and if that comes through, the installation could begin supplying ions for treatment and research in fiscal year 1990.
The planners opted for a synchrotron that can deliver a variety of ions at variable energies because they see possibilities for the heavier ions. Joseph R. Castro of LBL reported that of 800 patients treated at LBL with heavy charged particles, 87 have been treated with ions heavier than carbon, most (77) with neon. Their conditions included inoperable tumors in the abdomen (carcinoma of the pancreas), thorax and brain (malignant gliomas). The procedure, says Castro, is to "approach slowly from the known to the unknown," studying the radiation's effect on the tumors and on nearby normal tissues. Later randomized studies of its effectiveness are planned. Not much is known about Delayed effects of the heavy ion treatment, Castro reports, as this group of patients, confined for ethical reasons to those for whom all other treatments had failed, yielded only two who survived as long as 36 months.
At the same time, the much-used protons and helium ions have begun to treat a condition called arteriovenous malformation (AVMs). AVMs are not tumors but distortions of the capillaries connecting an arteriole and a small vein in the brain. The Capillaries develop "balloons" and serpentine twists. AVMs can bleed, causing severe headaches, seizures, even death. There are 500,000 cases in the United States and Canada, says Jacob I. Fabrikant of LBL--250 new ones a year in California alone. Twenty-five percent of AVMs are inoperable, he says.
Three institutions are experimenting with ionic treatment of AVMs, Fabrikant reports: the University of Uppsala in Sweden, Harvard University and LBL. So far 110 patients have been treated with helium at LBL. The treatment eradicates the AVM, restoring a normal appearance to the blood vessels, and does it better than X-rays, gamma rays or problems, Fabrikant says. There is also a cost advantage: Radiation treatment for this condition costs $8,000; a comparable neurosurgical procedure, $30,000.
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|Author:||Thomsen, Dietrick E.|
|Date:||May 11, 1985|
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