Trapping and re-use system for radioactive xenon in nuclear medicine

Different methods of trapping radioactive xenon are reviewed. Trapping by adsorption on activated charcoal has the advantage of being simple and cheap and also makes it possible to recycle the xenon. An activated charcoal trapping system is described which can extract 133Xe from 1001 of expired air in 10 min from patients undergoing diagnostic pulmonary or circulation studies. Details of the construction are discussed. The trapped gas can be rapidly released and returned to the spirometer. Substantial reduction of costs can be achieved with 133Xe; this becomes even more important as accelerator-produced 127Xe comes into more general use.