This paper presents experiences in developing a simple, inexpensive radioactive gas monitoring system that proved to be practical and useful at a clinical and research Positron Emission Tomography (PET) Center. The system is described from four key aspects: (1) design of radiation detectors and calibrations; (2) use of an existing PC-based hospital-wide facility management network; (3) placement and oversight of real-time PC monitor stations; and (4) modification of a ventilation system in the PET center. The radiation safety oversight efficacy of a real-time PC-based radioactive gas monitoring system in the academic PET center also is discussed.