Abstract
This chapter examines the differences in the physical, chemical, and biological events associated with radiations that have a high rate of linear transfer of energy compared to X-rays and gamma rays. There are several important sources of high linear energy transfer (LET) radiations in the environment. One of the most important of these from the health protection point of view is the neutron radiations that are produced in the course of power generation from nuclear fission. Astronauts in the space environment will also be faced with significant sources of high LET radiation, particularly from the high-energy charged particle environment. Significant high LET radiations are also generated from radiation generating equipment in modern physics research (high-energy accelerators), and from advanced equipment used in radiotherapy of cancer and other diseases. The general effectiveness of a given radiation to produce lesions or irreparable damage in bioactive molecules depends to a great extent on the spatial distribution of the ionization and excitation events that occur in the medium. For low LET radiations, the average spacing between energy transfer events along the track of the charged particle (the scattered electron) will be on the order of hundreds of nanometers. Therefore, there can be a little or no cooperative interaction between these events that lead to irreparable or misreparable damage to the DNA molecule. For high LET radiations, the formation of regions of ionization will be close together and will, in the limit, form a continuous chain or column of ionization damage, again, either by action in water or in the biomolecules themselves.
Published Version
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