The early attempts to employ the roentgen rays and radium for therapeutic purposes were followed very frequently by more or less severe burns of the skin in the area of irradiation. It was shown subsequently that this effect was due to the action on the skin of the soft roentgen rays and the soft beta rays of radium. Methods were then developed of filtering off the soft radiations by the aid of various metals and other substances placed between the source of the radiations and the skin.
The methods of radium therapy commonly employed at present consist in the application of the radium over the surface of the area to be treated, or in the insertion into the tissue of metal needles containing radium. In both instances, the radium rays are filtered in such a manner that only the gamma rays of radium penetrate into the tissues and act as
LEVIN I, LEVINE M. THE ACTION OF BURIED GLASS CAPILLARIES OF RADIUM EMANATION ON PLANT AND ANIMAL TISSUESAN EXPERIMENTAL AND CLINICAL STUDY. JAMA. 1924;83(21):1645–1650. doi:10.1001/jama.1924.02660210015004