The rational and successful application of radium therapy requires a knowledge of the fundamental physical properties of radium and of the biochemical tissue reactions to radium energy.
In the continuous process of spontaneous disintegration of radium, there are produced alpha and beta electromagnetic particles or rays and gamma rays, the latter being nonmaterial electromagnetic pulsations of the ether. The alpha particle is the nucleus of a helium atom with two positive charges of electricity, and because it is readily absorbed by the glass container or the varnished surface of an applicator, is of neglible value in radiotherapy. Beta rays or particles are negative electrons of varying high velocity with corresponding differences in their power of penetration. Those of low speed are absorbed by from 1 to 5 mm. of aluminum, and 2 mm. of lead will absorb all beta rays (Failla). Gamma rays are of different wave lengths and are