Supplementary Material for: Adverse event following change in brachytherapy plaque cleaning chemicals: a case series

Introduction:
The brachytherapy plaques used for uveal melanoma treatment are reused following sterilization processes. In this case series, we report patients with adverse reaction following a new cleaning procedure for brachytherapy plaques.
Case Presentations:
The brachytherapy plaque sewn on the outer eyewall would be removed following the delivery of calculated radiation dose. They are reused following standard calibration testing and sterilization processes. From September 2021 to January 2022, 6 patients treated with Ruthenium-106 plaque brachytherapy presented with severe unilateral pain, eyelid swelling and conjunctival injection with hemorrhage 1-2 days following plaque insertion. The surgeons observed a frosted appearance of the plaques in contrast to the normal shiny look during removal. The unusual severe post-operative reactions and the frosted appearance of plaques led to further investigations. A change in sterilization procedures with the use of LifeCleanTM instead of PerasafeTM was noticed. Ruthenium-106 brachytherapy plaques contain a uniformly distributed radioactive source covered by a thin silver shield. A test was performed by using two plates of pure silver that underwent its respective cleaning procedure using either PerasafeTM or LifeCleanTM.
Conclusion:
The test results demonstrated formation of silver chloride with LifeCleanTM, while no such formation with PerasafeTM. We did not observe any new cases of severe post-operative reaction or frosting of plaques after changing back to PerasafeTM. Chlorine salt deposits probably contributed to severe inflammatory reaction of ocular surface.