Lasers nudge into nuclear medicine.

Medical studies and treatments using short-lived radioactive isotopes typically require a nearby cyclotron, the bulky and costly particle accelerator that makes the fleeting elements.

Researchers from Japan, Russia, and the United States now have shown that a relatively cheap, tabletop laser can produce a medical isotope. However, the laser-generated quantities are so far too small for clinical use, says team member Anatoly M. Maksimchuk of the University of Michigan in Ann Arbor.

The experiments, described in the Jan. 29 APPLIED PHYSICS LETTERS, build on 1999 findings by this team and two other research groups. The scientists found then that high-power, ultrashort-pulse lasers can accelerate protons and heavier ions (SN: 12/4/99, p. 367). In taking the next step, Maksimchuk and his colleagues fired laser-driven proton-neutron pairs, or deuterons, at a boron target to produce carbon-11. Doctors and researchers use this isotope in positron emission tomography scans for cancer diagnosis and other purposes.

Laser accelerators may soon be able to dramatically increase their production of isotopes, Maksimchuk predicts. To compete with cyclotrons, however, the new accelerators need larger lasers. Maksimchuk notes that besides making isotopes, the lasers generate tight, short bursts of protons that could become cancer treatments in and of themselves.

--P.W.