THE RELATIVE BIOLOGICAL EFFECTIVENESS OF 200 KV. AND 23.5 MEV. X RADIATION

Publisher Website
Google Scholar
Abstract
A substantial number of transplanted mouse tumors (adenocarcinoma E0771 and sarcoma 37) were exposed to X radiation at 200 kv. and 23.5 Mev. Irradiation was confined entirely to the tumor. It was found that regression rate, as measured by the decrease in the total volume of the tumor, could be used as a measure of the effectiveness of a radiation. With this method the 23.5 Mev. radiation was found to be 0.83 times as effective as 200 kv. radiation. This may be due to the lower specific ionization of the electron tracks produced by the betatron radiation. Measurements of the lethal regression were also carried out in a smaller number of tumors using both types of radiation. The betatron radiation was found to be 0.85 times as effective as 200 kv. radiation, in agreement with the figure obtained using the regression rate.