Development of the DUMBO imaging device for beta-emitting radionuclides within the ISOLPHARM collaboration

Existing β -imaging devices with real-time image reconstruction typically have a field of view (FOV) of about 0.1 cm 2 , which is too small for imaging large cell cultures as a whole. To provide a complementary tool in radiopharmaceutical research, the Detector Using Maps for Beta-rays Observations (DUMBO) β -imaging device was developed, featuring lower spatial resolution but a larger FOV and non-invasive imaging capability. The prototype presented in this work consists of two ALICE PIxel DEtector (ALPIDE) chips, providing a total sensitive area of 3 c m × 3 c m . The sample can be positioned with three degrees of freedom, two of which are motorized using commercial stepper actuators. The performance was evaluated through Geant4 simulations and experimental measurements with the medical radionuclide 111 Ag. Plastic and hydrogel phantoms were imaged to assess the device response to different sample types. The circular shape of the vials containing aqueous 111 Ag solutions, as well as the structure of the plastic phantoms with 1-3 mm-wide channels, were clearly resolved. The simulated spatial resolution, which depends on the distance between source and detector, could reach values as good as 0.3 mm; however, sample preparation limited the experimentally achieved resolution. DUMBO demonstrated stable operation, straightforward sample handling, and clear detection capability for samples with activities of the order of 100 kBq.