Radiation Safety Challenges in Lu-177 PSMA: A Technologist’s Prospective

3035 Objectives: Lu-177 can be created in two different ways: direct or indirect reaction. No contaminates are produced in the indirect reaction. However, the direct method could generate a small percentage of metastable Lu-177 (Lu-177m) with a half-life of 161 days. The NRC states that Lu-177 dotatate is the only lutetium-177 product that is created with the indirect reaction. Per the NRC, any Lu-177 products other than Lu-177 dotatate (Lutathera) can produce the buildup of radioactive waste including the contaminant Lu-177m. According to 10 CFR 35.92 “Decay in Storage”, facilities cannot store radioactive waste with a half-life greater than 120 days. In our institution, we offer Lu-177 dotatate as standard of care for NET patients. In addition, we are also using Lu-177 PSMA-617 as part of an ongoing clinical trial in patients with or prostate cancer. We aimed to determine if radiation safety issues for Lu-177 PSMA patients are different than those of Lu-177 dotatate patients. Additionally, we are preparing our center for the expected future use of Lu-177 PSMA in our new hospital which is expected to open in September of 2020. Methods: For both Lu-177 dotatate and Lu-177 PSMA, we used the same contamination reduction techniques including wrapping the toilet in plastic wrap to reduce the absorption of Lu-177 into the porous porcelain toilets as well as covering grouted floor surfaces around the toilet with a large surgical/absorbent drape. Our NM department still encounters contamination issues with the restrooms even after we have wrapped them. Patients instructions included avoiding prolonged contact with others for the first two days, maintaining good hygiene for seven days including cleaning spilled urine and flushing the toilet twice after each use. Per protocol, we surveyed our “hot” bathroom designated for our therapy patients before and after each treatment. A log was kept to contrast and compared differences between Lu-177 dotatate and Lu-PSMA experiences. Results: In Lu-177 PSMA, urine contamination was more common (likely due to prostate pathology) and more difficult to remove and took longer to decay (likely due to the Lu-177m contaminant) than in Lu-177 dotatate. The data we collected indicates that the Lu-177 PSMA contamination takes up to twice as long to decay than the Lu-177 dotatate. Due to the increased contamination resulting from PSMA therapies, the patient bathroom within the NM area has been closed to other patients for approximately three months due to the continuous number of Lu-177 PSMA therapies we have performed. Thus, NM non-therapy patients are using the staff restroom within our NM center. For departments with only one restroom, contamination from these therapies could result in restroom closures, which may lead to non-therapy patients using restrooms not monitored by radiation safety. We redesigned our theranostic area in our new hospital to address the new challenges. Changes include a dedicated bathroom for theranostic patients with stainless steel toilets and sinks as well as seamless flooring. Options for waste disposal and are also being evaluated. Conclusions: The long-awaited approval for Lu-177 PSMA is expected to be extremely positive for NM; however, it may bring with it unique and new challenges. It behooves NM facilities to be aware of and be ready for the delivery of Lu-177 PSMA theranostic treatment of patients with prostate cancer.