Update and Extension of Release Criteria for Canine 117m Sn Treatments

Tin-117 m ( 117m Sn) is used to treat dogs with osteoarthritic joints by radiosynoviorthesis. The internal conversion and Auger electrons emitted by the 117m Sn provide the therapeutic effect. Sn-117 m also emits x rays and gamma rays, of which the most significant is 158.6 keV. Accurate information regarding the interactions of a person with a treated dog is needed to determine the person's total dose and thus regulatory compliance; i.e., a time and motion study. Prior studies have characterized the radiation field emitted by a treated dog, determined the effective dose rates to a person based on those radiation fields, and evaluated dog-human interactions. These studies have been tied together to calculate the prospective dose to the owner of a treated dog. The behavior modifications needed to comply with public dose limits were identified, and a template for written instructions limiting dose was developed. Further calculations based on the written instructions were made to determine the necessary duration of the instructions. The result is guidance that may be used by veterinary practitioners to release treated dogs in accordance with the public dose limits.