RT Journal Article SR Electronic T1 133Xe Contamination Found in Internal Bacteria Filter of Xenon Ventilation System JF Journal of Nuclear Medicine Technology JO J. Nucl. Med. Technol. FD Society of Nuclear Medicine SP 170 OP 172 VO 31 IS 3 A1 Hackett, Michael T. A1 Collins, Judith A. A1 Wierzbinski, Rebecca S. YR 2003 UL http://tech.snmjournals.org/content/31/3/170.abstract AB Objective: We report on 133Xe contamination found in the reusable internal bacteria filter of our xenon ventilation system. Methods: Internal bacteria filters (n = 6) were evaluated after approximately 1 mo of normal use. The ventilation system was evacuated twice to eliminate 133Xe in the system before removal of the filter. Upon removal, the filter was monitored using a survey meter with an energy-compensated probe and was imaged on a scintillation camera. The filter was monitored and imaged over several days and was stored in a fume hood. Results: Estimated 133Xe activity in each filter immediately after removal ranged from 132 to 2,035 kBq (3.6–55.0 μCi), based on imaging. Initial surface radiation levels ranged from 0.4 to 4.5 μSv/h (0.04–0.45 mrem/h). The 133Xe activity did not readily leave the filter over time (i.e., time to reach half the counts of the initial decay-corrected image ranged from <6 to >72 h). The majority of the image counts (~70%) were seen in 2 distinctive areas in the filter. They corresponded to sites where the manufacturer used polyurethane adhesive to attach the fiberglass filter medium to the filter housing. Conclusion: 133Xe contamination within the reusable internal bacteria filter of our ventilation system was easily detected by a survey meter and imaging. Although initial activities and surface radiation levels were low, radiation safety practices would dictate that a 133Xe-contaminated bacteria filter be stored preferably in a fume hood until it cannot be distinguished from background before autoclaving or disposal.