Characterisation of a β detector on positron emitters for medical applications

•Radio Guided Surgery (RGS) based on βradiation extends its range of application.•PET radiotracers can be exploited as tumor marker enabling complete resection.•RGS based on β-probe and 68 Ga-emitters is for neuroendocrine and prostate cancers. Radio Guided Surgery (RGS) is a technique that helps the surgeon to achieve an as complete as possible tumor resection, thanks to the intraoperative detection of particles emitted by a radio tracer that bounds to tumoral cells. In the last years, a novel approach to this technique has been proposed that, exploiting β- emitting radio tracers, overtakes some limitations of established γ-RGS. In this context, a first prototype of an intraoperative β particle detector, based on a high light yield and low density organic scintillator, has been developed and characterised on pure β- emitters, like 90Y. The demonstrated very high efficiency to β- particles, together with the remarkable transparency to photons, suggested the possibility to use this detector also with β+ emitting sources, that have plenty of applications in nuclear medicine. In this paper, we present upgrades and optimisations performed to the detector to reveal such particles. Laboratory measurement have been performed on liquid Ga68 source, and were used to validate and tune a Monte Carlo simulation. The upgraded detector has an ~80% efficiency to electrons above ~110keV, reaching a plateau value of ~95%. At the same time, the probe is substantially transparent to photons below ~200keV, reaching a plateau value of ~3%. The new prototype seems to have promising characteristics to perform RGS also with β+ emitting isotopes.