Abstract
3066
Objectives: The use of I-131 for diagnosis and therapy of thyroid cancer ushered a new field of Theranostics in NM. Most NM facilities are comfortable following NRC guidelines regarding dosing and discharge instructions for patients undergoing such therapy. Recently, however, the introduction of Lu-177 Dotatate therapy in 2018 for Neuroendocrine tumors has brought new challenges compared to standard I-131 radionuclide therapy. It requires a team of healthcare workers with departmental pre- and post-therapy preparation as well as radiation safety concerns for a 4-6 hours therapy session. When Lu-177 (T1/2 = 6.7 days) is produced by neutron capture, Lu-177m is produced as a contaminant with a half-life of 161 days. According to the NRC, Lu-177m may contribute approximately 0.02% of the total amount of Lu-177. Lu-177m cannot be decayed in storage under the rule 10 CFR 35.92, “Decay-in-storage,” because its half-life is greater than 120 days. Although there are protocols and preparations set in place for handling currently used radionuclide therapeutic agents, most NM centers are not equipped to deal with radioisotopes with half-lives longer than 120 days. In this study, we focused on evaluating currently used short term and potential long term radiation safety solutions for the delivery of a theranostic program in NM facilities.
Methods: The patient preparation and protocols that are already set in place by hospitals for Lu-177 Dotatate therapy were reviewed. NM physicians and technologists that have been working with Lu-177 Dotatate therapy were interviewed about the current process and potential issues arising with Lu-177m.
Results: Following interviews with Nuclear Medicine staff and the review of the protocol and patient preparation for Lu-177 Dotatate therapy, it can be confirmed that additional challenges will follow the use of this radiopharmaceutical and ones similar to it. In fact, some NM facilities elected not to offer such therapy due to radiation safety concerns coupled with the lengthy protocol. Upon properly lining the bathroom floor, patients should be informed to sit while voiding to prevent splatter and reduce the risk of contamination and radiation exposure. Future NM centers should have a dedicated theranostic area with its own properly designed bathroom. Considering the 161 day half-life of the contaminant Lu-177m, a dedicated properly lined bathroom should be made of a porous material that cannot harbor the radiation and will allow for easier clean-up such as stainless steel instead of porcelain sinks and toilets and linoleum instead of tile flooring. Theranostic areas should be routinely monitored for possible Lu-177m contamination. When present, such contamination cannot be stored to decay, the department must be contracted with an outside company who will take care of the waste disposal and assure that it is properly being handled.
Conclusions: Currently, there are protocols and procedures set in place for delivering Lu-177 Dotatate therapy, but there is no protocol when dealing with issues related to Lu-177m. The long-term solutions presented for these issues should be prospectively implemented into each facility protocol when delivering Lu-177 therapies. With improved patient and department preparations, proper techniques of lining restrooms, proper waste disposal, and well informed team members, the risk of urine contamination as well as radiation exposure will significantly decrease. The use of Lu-177 Dotatate is on the rise and other similar therapies are progressing towards approval in the near future, therefore, being informed and implementing these long term solutions ensures little to no issues while treating patients.