Beta-sensitive intraoperative probes utilizing dual, stacked ion-implanted-silicon detectors: proof of principle

Successful development of a beta-sensitive intraoperative probe requires that the device be capable of selectively rejecting or reducing signals from background sources of photons. To address this problem we have designed and tested a unique stacked, dual solid-state detector probe. The first ion-implanted-semiconductor wafer detects a combination of beta particles and background photons, and the second wafer detects just the photon flux, due to the beta shielding effects of the first wafer. Using the data acquired from a positron-emitting source (/sup 18/F), four methods of photon correction were tested. The scheme which incorporated a weighted subtraction of the data from the photon monitoring detector from the front detector was found to optimize performance. Sensitivity to beta particles was 4121.0/spl plusmn/52.3 cps//spl mu/Ci, and the selectivity index was 0.99. Monte Carlo simulations revealed that these values are close to the theoretically optimal values possible, given the probe and source geometries. Additionally, a simulated tumor search utilizing an anthropomorphic torso phantom demonstrated the excellent potential of this device to intraoperatively localize sources of radiotracer-avid disease, such as malignant tumors. In summary, a dual, stacked ion-implanted-silicon detector beta-sensitive probe system has been developed and successfully tested.