Theory of RBE for Heavy Ion Bombardment of Dry Enzymes and Viruses

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Abstract
The response of dry enzymes and viruses to heavy ion bombardment may be predicted from their response to gamma-irradiation (and no further knowledge of their size and structure). The molecules are approximated as point particles whose response to ionization is the same for heavy ion bombardment as for gamma-rays. From the [delta]-ray distribution formula and an extrapolated range-energy relation for electrons, the radial distribution of secondary ionization energy may be found. Under this dosage distribution the inactivation probability may be found as a function of radial distance from the ion''s path, and then may be integrated over all space to find the inactivation cross-section. These essentially geometric theoretical relations between the gamma-ray D37 values and the inactivation cross section constitute a complete theory of RBE [relative biological effectiveness] for the heavy ion bombardment of these substances. Thoretical relationships agree with published experimental values to an average deviation of 15% for the enzymes [beta]-galactosidase and trypsin, and for T-1 and [PHI]X -174 bacteriophages, when bombarded with ions ranging from Z = 1 to 18, at ion speeds of 0.07 c (2.3 MeV/nucleon) and 0.145 c (10 MeV/nucleon).