Small End-Window and Angle-Window Geiger Counters: Measurement of Radioactivity in Intraocular Tumors Following Injection of Radioactive Phosphorus

The use of radioactive phosphorus has become a valuable aid in oncologic studies and in the diagnosis of ocular neoplasms. Measurement of the uptake of this radioactive substance by the tissue under investigation gives an index that furnishes a substantial evaluation of certain metabolic processes occurring in that tissue. To facilitate such measurements, special Geiger counter probes * have been constructed which provide satisfactory results for both anterior and posterior ocular tumors. Bettman 4 has also designed a scintillation counter for similar use. Recently, we have been studying the uptake of radioactive phosphorus by ocular neoplasms in experimental animals, with the hope of establishing a firm basis for the understanding of similar cases observed clinically. In these investigations, we originally used the same counter probes on animals that had been designed for clinical determinations. Both the end-window and the angle-type counters, however, proved to be a little too large for satisfactory