A solid-state intraoperative beta probe system

Successful beta-sensitive intraoperative probes must be capable of detectin g relatively small amounts of beta-emitting radionuclides in an environment where a significant photon background exists. The probe system described i n this investigation utilized a new photon correction scheme consisting of a stack of two ion-implanted-silicon detectors (IISD's) mounted in a compac t unit. The rear detector operated as a photon monitor, whose data mas used to correct for photon contamination present in the front detector's readin gs. The completely battery-powered system incorporated a computer-controlle d data acquisition and processing system. Positron and photon detection sen sitivities were measured using Fluorine-18, The probe was found to have a p ositron detection sensitivity of 7.21 +/- 0.11 cps/nCi and a 0.0004 +/- 0.0 389 cps/nCi photon detection sensitivity. In a simulated search for tumor r emnants following a tumor resection using a phantom presenting a realistic annihilation photon background, the intraoperative probe was capable of def initively identifying 12-mm- and 6-mm-diameter, 1-mm-thick disks of simulat ed tumor. Localization of a 3-mm-diameter disk was also demonstrated. These excellent results indicate that this system may be a useful aid for radion uclide-guided cancer surgeries.