Location of brain tumors by means of radioactive phosphorus.

Precise location of cerebral tumors at operation has been accomplished by means of a miniature GeigerMuller counter employed as a probe. With such a purpose in view, one of us (B. S.) suggested, on theoretical grounds, that radioactive phosphorus might concentrate in cerebral tumors. In order to demonstrate the feasibility of this technic, it was essential to prove that radioactive phosphorus would actually concentrate in cerebral tumors to a degree significantly greater thanin normal gray and white matter. 1 Preliminary experiments were carried out in which tracer doses of radioactive phosphorus, as a buffered phosphate solution, were given intravenously to patients with various types of cerebral tumor. Aliquots of tumor removed at intervals after injection of P 32 were compared for radioactivity with white and with gray matter removed at the same time. The radioactivity of tumor tissue ranged from 5.8 to 110 times greater than that of adjacent