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Article
January 28, 1974

Medical News

JAMA. 1974;227(4):377-387. doi:10.1001/jama.1974.03230170001001
Abstract

Neutrons, negative pi mesons may boost cancer radiotherapy  If recent radiology meetings are any indication, the age of particulate radiation therapy, as an addition to or possibly an eventual replacement for electromagnetic radiation therapy, is almost here. Neutron beams are being used in clinical trials here and in England, and negative pi meson beams, that so far have been tested only in plant roots and some experimental animals, loom in the future.Why all the interest? First, the particles— neutrons, negative pi mesons (or pions), and accelerated heavy ions—produce a higher density of ionizations than either x-rays or gamma rays. For this reason, they are called high LET (linear energy transfer) radiation, whereas electromagnetic radiation is called low LET radiation. This difference in density of ionizations is significant because it takes a certain number of ionization events within a cell to cause cell death; hence low LET radiation produces differ in their

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