The Rates of Absorption of Radio-Sodium in Normal Human Subjects

The internal admistration of radio-sodium in the form of sodium chloride was first performed at the University of California Hospital in March of 1936 upon a subject with lymphatic leukemia. The radioactivity of the patient and his excreta was observed in addition to any possible clinical responses. A second patient with a myelogenous leukemia received the same substance, but of considerably greater activity. No definite clinical improvement or toxic effects were observed; but data referable to the concentration of the radio-sodium in the body fluids and its excretion were obtained from these studies and are reported elsewhere.' Following the intraduodenal administration of the radio-sodium to the second patient it was found that for the succeeding 8 hours the measured activity of his body was greater than was to be expected, allowing for the gamma radiation absorbed by the tissues and the amount of radio-sodium lost by excretion. Recently a third patient, suffering from a reticulum-cell sarcoma of the cervical lymph nodes, was given the activated salt by mouth and the same phenomena were observed for a period of 13 hours.2 This apparently anomalous behavior of the radio-sodium when given by mouth or by duodenal tube, as contrasted to the results obtained after intravenous administration, was thought to be due to the fact that it was more slowly absorbed than might be expected. This problem has been investigated further by studies concerning the apparent rates of absorption of radiosodium in normal human subjects. Preparation of the Radio-Sodium.-The radio-sodium was prepared by the deuteron bombardment of crystalline sodium caloride using the magnetic resonance accelerator which was developed by Lawrence and Livingston3 and later re-designed by Lawrence and Cooksey4 of the Radiation Laboratory of the University of California at Berkeley. This apparatus, commonly described as the Cyclotron, has been constructed for the multiple acceleration of light ions to high speeds. The deuterons spiral around within a drum-shaped chamber lying between the poles of apowerful electromagnet. The combined action of the magnetic field and a high frequency oscillating electric field upon these particles produces progressive increments of velocity with every revolution of the ions within the chamber so that their terminal energy upon emerging at the periphery is in the neighborhood of 6,000,000 electron volts. These rapidly moving particles, which consist of a proton and a neutron bound together and are isotopes of ordinary hydrogen ions, stream out of the cyclotron as a narrow beam which is directed