Radiation Exposure to the Nuclear Medicine Technologist as a Result of Lutathera Administration

Objectives: Lutathera (lutetium Lu-177 dotatate) was approved for the treatment of somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors (GEP-NETS) in January 2018. With this innovative therapy delivering 200 mCi each dose for the duration of four therapies, it is important to ensure the exposure to the nuclear medicine technologist (NMT) is minimal. This study analyzes the radiation exposure to the NMT throughout the administration of Lutathera. Methods: Several forms of dosimetry monitoring devices were utilized to measure the radiation exposure to surrounding areas, as well as the NMT, throughout Lutathera administration. These methods included dosimeter badges and self-reading electronic dosimeters. Although these readings were taken into account, an ion chamber was determined to be better suited for measuring radiation dose to the NMT. The ion chamber accurately represented the distance that the NMT stood from the dose and patient during the setup and infusion of the therapy-21.6 inches from each location. For the duration of five therapies, a survey was taken every 10 minutes from this distance to accurately portray the amount of time the NMT spends in the room throughout the therapy. A one-meter discharge reading was obtained from the patient to ensure no increase in activity; this was taken three hours post-infusion. To better understand the data recovered from the therapies, it was compared to the average one-meter discharge readings from past 100 mCi I-131 therapies from this institution. Results: The radiation dose rate surveyed from the ion chamber on average measured 1.9 mR/h. Prior to each patient's release, an average discharge reading of 1.4 mR/h was obtained. The average one-meter discharge reading post 100 mCi I-131 therapy from this institution is 14.94 mR/h. A one-tailed t-test was performed yielding a p-value of 1.19E-11, proving the significance in difference between I-131 and Lutathera radiation exposure. Conclusions: When comparing the average one-meter discharge reading for Lutathera, 1.4 mR/h (or 1.9 mR/h given off during therapy) is substantially less than I-131 therapy-a therapy that has been administered for decades. Prior to the decision to use the ion chamber in this study, various other dosimetry measurement devices were trialed-data retrieved from the ion chamber was determined to be most valid. Patient population was limited in this study due to the prolonged determination of the best-suited dosimetry