An improved hand-held four-detector γ-probe for radioassisted oncological surgery

The performance of an improved intraoperative γ-probe for radioassisted oncological surgery is presented and discussed. The probe is based on a square array of four 5×5 mm2 coplanar CdTe room temperature semiconductor detectors and each detector has an independent read out electronic chain, allowing an original handling of the signal. Therefore, the search for γ-emission hot points may be carried out in two different, independent ways: akes the new probe sensitive to the bidimensional gradient of the γ-ray flux, measured on the scanned plane. Furthermore, the algebraic sign of the difference indicates in which direction the probe should be moved to best locate the γ-source. Due to these characteristics, both the errors in the localization of a single, small size γ-source and the average measuring time are practically halved with respect to those obtained with a conventional single detector probe. In addition, a computer analysis is performed in order to evaluate the performances of different types of collimators in reducing the contribution of a second source close to the source under examination. This situation occurs, for example, when the probe is used in the framework of the sentinel-node surgical technique.