The 15O gas production system selects the gas production mode, monitors gas delivery conditions and performs quality control needed during the production and delivery of continuous flow radioactive gas for equilibrium and bolus PET studies. Target gas switches choose the appropriate valve positioning for [15O]H2O, [15O]O2 or [15O]CO production while flow rate, pressure and radioactivity are constantly monitored. The system also includes an IBM PC interfaced gas chromatograph which provides chemical and radiochemical quality control by on-line, real time, gas sampling of the delivery line.