Excerpt from Radium, Vol. 4: A Monthly Journal Devoted to the Chemistry, Physics, and Therapeutics of Radium and Radio-Active Substances; November, 1914 With regard to the use of radioactive substances in the treat ment of cancer, Dr. Levin says: The-rationale of the radiotherapy in malignant tumors must be looked for in the so-called selective action of the rays on the cancer cell. The Roentgen rays and the rays of the radioactive substances are absorbed by the cells of the radiated tissue. Through the biochemical action of the'rays the cells become dis eased. The injury caused in the cells by the radiations may differ in degree in accordance with the quantity of the rays absorbed. Cells only slightly injured may recover while a severer injury may completely destroy the cell. Every cell of the animal or plant organism is susceptible to injurious action of the radiations. But the susceptibility varies in degree with the cells of different tissues. The cells of malignant tumors are a great deal more susceptible to the action of the rays than the cells of the normal tissues surrounding the tumor. If the rays are employed of a cor rect quality and in a sufficient quantity, it is possible to destroy all the cancer cells in a certain locality and at the same time leave the normal tissues either intact or so slightly injured, that they ultimately recover. This quantitatively selective influence of the rays may reach to a depth of at least three and one-half cm. Technique of Radium Therapy. The alpha and beta rays which constitute the greater part of the radiation are called soft rays and have little power of penetration. They are ah sorbed completely by the superficial layers of tissue, and the quan tity absorbed by each cell is so great that all the tissues are de stroyed, and the action of the rays is caustic. The hard gamma rays represent only about 1 per cent. Of the radiation, they pene trate into the deeper layers of tissue and exert the selective action on the cancer cells. It is possible that a small percentage of the hardest beta rays have a similar action. With the small quanti ties of radium used formerly the gamma rays had no influence on the tissues. The modern method of radium therapy consists in employing larger quantities of radioactive substances and apply ing them for a longer period of time. The soft caustic alpha and beta rays, which would be very injurious with the larger quanti ties of radium used, are filtered ofi by layers of some heavy metal which absorbs the soft rays. The methods vary with the different investigators some of them employing extremely large quantities of the substance as high as 800 mgm. Of mesothorium at one time. Recently it was shown that with such extremely large quantities the selective action may again be lost and the whole organism of the patient injured. It would lead too far to describe all the vari ous methods employed and the writer will present only his own method of application of radioactive substances. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.