Sturchio, Glenn

Radioactive seed localization (RSL) using 125 I is widely employed for the surgical resection of nonpalpable breast lesions due to its precision and scheduling flexibility. Although clinical experience supports its safety, quantifying radiation dose to surrounding healthy breast tissue remains important for establishing conservative operational guidelines, including acceptable implant duration prior to surgery. In this study, cumulative dose to healthy breast tissue from an implanted 125 I localization seed was evaluated using two independent computational approaches: a simplified hemispherical breast model implemented in MATLAB and a Monte Carlo simulation developed in Mathematica. Both models incorporated dosimetric parameters from AAPM Task Group 43, including the dose-rate constant, radial dose function, and two-dimensional anisotropy function, along with tissue properties consistent with International Commission on Radiological Protection recommendations. Results from both models demonstrated that cumulative dose decreases rapidly with increasing distance from the seed and increases slowly with implantation time due to the low dose rate and long half-life of 125 I. At a distance of 1 cm, cumulative dose reached approximately 3–4 cGy after 5 d and approximately 50 cGy only after extended implantation times exceeding 200 d. Agreement between the MATLAB and Monte Carlo models was within expected limits given differences in deterministic and stochastic modeling approaches. These findings indicate that radiation dose to healthy breast tissue from RSL remains well below thresholds associated with deterministic effects for clinically relevant implantation times. The results support the use of a conservative “no later than” removal date while reaffirming the radiological safety and practical advantages of 125 I seed localization in breast cancer surgery.

After implementing a process for flagging readmitted radiopharmaceutical therapy patients, it was discovered that major assumptions for these patients were not correct, specifically the magnitude of patients and the location of the readmissions. Data collected from May to December 2024 revealed 501 post-therapy patient encounters out of 1,139 administrations. Analysis showed varying return rates across different radiopharmaceuticals and departments, highlighting the need for updated radiation safety response. Results indicated that most encounters occurred in outpatient settings, with contamination above action levels found in 61% of responses. The study underscores the importance of continuous assessment and collaboration among stakeholders to adapt to new radiopharmaceutical therapies and ensure effective radiation safety practices.

The radiopharmaceutical therapy field is experiencing a surge of novel treatments and expanded uses for existing treatments, broadening the range of patients that can be treated. This expansion presents new challenges for managing patient release due to new patient populations with additional comorbidities, increasing the incidence of patients requiring care shortly after administration. This paper outlines the challenges and potential solutions for managing readmitted radiopharmaceutical therapy patients. It discusses the importance of having radiation protection policies and procedures in place for staff who may be unfamiliar with radiation. The paper also highlights the need for just-in-time training and radiation monitoring equipment for care staff, as well as the development of a notification system within the electronic health record to ensure staff can safely care for these patients. Preparing for these eventualities is essential for implementing a radiopharmaceutical therapy program that is ready for the expansion of existing and novel treatments.

Abstract Lutetium Dotatate radiopharmaceutical therapy (Lutathera) was approved by the United States Food and Drug Administration in 2018 and is used to treat somatostatin receptor positive neuroendocrine tumors. With all new radiopharmaceutical therapies, the radiation exposure to members of the public from the patient who received the therapy must be within regulatory limits and safe. If the patient will expose members of the public to too much radiation, the therapy must be performed on an inpatient basis. This paper shows that the administration of Lutathera can be done on an outpatient basis and provides safety and travel restrictions that should be communicated to the patient prior to leaving. The guidance presented herein serves as a basis for medical institutions looking to use Lutathera to treat patients.