Radioactive medicine without the nuclear headache
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The particles pick up speed with each rotation and begin to drift outward, until they near the outermost edge, travelling at close to 20 per cent of the speed of light—about 60,000 kilometres per second—fast enough to take you around the Earth 1.5 times in a second. Then the particles are stripped of their electrons and spat out in an intense proton beam that passes through the moly-100 target. Some of the protons will hit the nucleus of a moly-100 atom, blowing off two subatomic particles called neutrons, and transform it into technetium-99m.
The approach offers some added perks: Cyclotrons can be used to produce tracers for other nuclear medicine procedures, including PET scans, which are expected to increase in the future. Moly-100 is a naturally occurring isotope mined in several parts of the world, and the moly-100 target can be recycled and reused.
If the teams are successful, each cyclotron could produce more than enough technetium-99m for its region. “Everything is going well right now, I’m optimistic,” says Brigitte Gue’rin, a research director at Sherbrooke, who says that with the new machine, two runs of six hours each would produce 800 doses of technetium-99m per day, and meet the needs of a population of 6 million.
“The biggest challenge right now is whether the cyclotron technology is robust and reliable enough to do this on a daily production basis,” says Dr. McEwan. He hopes they’ll have the answer by year-end.
“With 15 to 16 of these cyclotrons spread out across the country, we can supply 95 per cent of the population with all the technetium-99m needed,” he adds. “And investing in cyclotrons now will mean hospitals can meet the need for PET isotopes in the next five to 20 years.”
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Good to know
50 million nuclear medical body scans are performed each year around the world.
80% of these procedures use Technetium 99.
The ACSI TR24 cyclotron can accelerate particles at about a quarter of the speed of light.
Source: Advanced Cyclotron Systems Inc.
Medical procedures using Tc-99m
Myocardial perfusion - 56%
Bone scans - 17%
Other cardiovascular - 4%
Liver/Hepatobiliary - 7%
Respiratory - 4%
Thyroid/Parathyroid - 3%
Renal - 3%
Infection/inflammation - 2%
Tumor immaging - 2%
Other - 2%
Source: IMV 2007 Nuclear Medicine Market Summary Report, SECOR Analysis
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