In discussing this subject, data on radiation induced mammary gland neoplasia in the rat indicating that direct interaction between the radiation and target tissue is necessary for maximum neoplasia induction will be presented mainly. Other types of radiation induced neoplasia, in which little or no information on the mechanisms involved is available, will be discussed briefly. In particular, investigations on radiation induced mouse lymphoma will be reviewed, in which neoplasia appears to be an abscopal effect. Implications of these data will be discussed, particularly with regard to possible mechanisms involved, and extrapolation to man.

The generic term "chemonuclear" has been assigned to any chemical process system using nuclear energy as the prime energy source. The type of effect which induces the chemical change, or produces the chemical is of importance in classifying the type of chemonuclear process, or reactor involved. Four types of effects are identified for this classification. These are radiation, thermal, electrical, and photolytic effects. The radiation effects include the interaction with matter of high energy particles, or photons carrying energy in the range of a million electron volts (MEV) or higher, and causing primarily ionization effects. Thermal effects include transfer of thermal energy to matter and usually is directed towards producing a thermodynamic equilibrium in the system. Electrical effects are concerned with interaction with matter of particles carrying energy in the range of electron volts up to thousands of electron volts (EV to KEV). The photolytic effects utilize photon energy in the range of infrared through the visible to the ultraviolet radiation (IR, Visible, and UV). As is evident, this classification is somewhat arbitrary since it is primarily based on a division of the energy spectrum which is in reality continuous. It does, however, separate the more conventional methods of inducing …

The pioneer study by Benjamin and Sluka in 1908 on inhibition of antibody formation by X-rays revealed the importance of the temporal relationship between exposure to radiation and injection of antigen. X-radiation delivered three days before injection of beef serum inhibited precipitin formation in rabbits. A similar exposure to X-rays delivered three days after injection of the antigen failed to repress production of specific antibody. These observations were partially confirmed in 1915 when Hektoen reported inhibition of hemolysin production in the rat when X-radiation was delivered either before or after injection of sheep red cells. Although an absolute difference in radiosensitivity was not evident, the depressant effect of radiation on antibody production appeared to be less effective when radiation was given after injection of the antigen.