Design and characterization of a biomedical device capable of pico-CI level beta detection for the study of cell metabolism

A new system is being developed to allow imaging of charged particles in microfluidic chip using position sensitive avalanche photodiodes (PSAPD). The new imaging system was created by placing the PSAPD detector with close proximity to the PDMS microchip. The new system therefore is capable of quantifying tiny amounts of these radiolabeled probes over time. The PSAPD can be used for the direct detection of positrons and other charged particles. In our studies, the performance of the system has been carried out. A gradient of solution containing radioactive positron emitting fluorodeoxyglucose (FDG) was imaged from a microchip. Results have shown that sensitivities as low as 56 plusmn 0.1 pCi in a 4 mm² region of interest (ROI) (14 pCi/mm²) and line pair spatial resolution of 0.5 mm can be achieved. Moreover, the application to cell biology was successfully performed in which currently radioactive signal from less than one hundred cells can be detected and resolved clearly in the system.