Fig. 2
Two-hole two-layered face mask (a) implemented in the inhalation/scavenging unit of a 15O-oxygen production/inhalation system. Radioactive gases are supplied inside the inner mask made of fabric (b), and a patient breathes in the radioactive gases during the inhalation period. Leaked radioactivity from the inner face mask is scavenged at a flow rate of approximately 30  L/min, to tank 2 through the scavenging tube connected to one of the holes in the outer mask (c). Inlet tube for the outer face mask is open so that fresh air can be continuously supplied while the face mask is on the patient’s face