Inert gases (e.g., ¹³³Xe) in nuclear medicine should be used in such a manner that no individual, other than the patient, is likely to receive a submersion dose greater than 2500 mrem over the course of one year. Inert gases shall be used in such a manner that the instantaneous levels of airborne radioactivity shall not exceed 5 times the inhalation derived air concentration (DAC) listed in 10 CFR 20, appendix B (1E-4 uCi/ml for ¹³³Xe).

Health Physics will assure that appropriate technical assistance and guidance is provided for achieving compliance with the above.

The room where the inert radioactive gas is used must be under negative pressure. The exhaust from the room where the inert gas is used shall be directly vented to the environment. Fresh air may be mixed with the exhaust stream so as to reduce the concentration of radioactive inert gas.

Health Physics shall approve machines used for the administration of radioactive inert gases to patients. The machines must feature:

1. A rebreathing system.
2. A charcoal filtered exhaust trap which will trap or hold most of the radioactive gases such that airborne radioactivity levels are not likely to exceed one DAC fraction at 1 meter from the machine’s exhaust.
3. A radiation monitor or other alarm system which indicates that the trap has failed or reached its maximum loading.

In the event the patient experiences breathing difficulties or other medical problems, the patient will be immediately disconnected from the machine. Appropriate first aid measures shall be conducted. As soon as practicable, the machine shall be shut off with the priority directed towards the well-being of the patient.