A Rare Case of Cesium-137 Source Leakage: Lessons for Clinical Medical Physicists
Abstract
Purpose
To report a rare failure of a sealed source Cesium-137 E-Vial used for dose calibrator quality control, describe the methods used for detection and characterization of the leak and emphasize implications for radiation safety, source integrity verification, and quality assurance procedures.
Methods
As part of a routine quarterly hot lab audit, wipe testing identified suspected Cesium-137 sealed source leakage. Instrument quality control and performance for the well counter was verified prior to performing wipe testing. Following wipe test results inconsistent with expected background levels, contamination surveys and historical QA data were reviewed. The investigation determined that the sealed source vial was leaking and measured results exceeded the trigger limit of 0.005 uCi (185 Bq) of removable contamination. Appropriate radiation safety controls were implemented and institutional and regulatory notifications were initiated.
Results
Contamination consistent with Cesium-137 leakage was confirmed and localized to the low-dose vial and the associated lead storage container. No personnel contamination, hot lab contamination beyond the immediate storage container or exposures exceeding regulatory limits were identified. The source was removed from service, secured, and managed in accordance with institutional and regulatory requirements. Follow up surveys confirmed successful containment with no other evidence of further contamination in the hot lab or mobile coach.
Conclusion
This rare case demonstrates that sealed source failures, although rare, can be identified through routine monitoring and audit activities. The findings underscore the importance of comprehensive audit programs, adherence to contamination monitoring practices and continued vigilance in environments where sealed sources are handled.