Radiation Contamination Following Cremation of a Deceased Patient Treated With a Radiopharmaceutical

Radiopharmaceuticals are radioactive compounds used for diagnostic and therapeutic purposes by many medical specialties. As of 2006 (the most recently reported data), 18.6 million nuclear medicine procedures were performed in the United States, with nearly 40 million performed worldwide.¹ Safety regulations are well established for radiopharmaceutical administration in living patients. However, radiopharmaceuticals present a unique and often overlooked postmortem safety challenge. Cremating an exposed patient volatilizes the radiopharmaceutical, which can then be inhaled by workers (or released into the adjacent community) and result in greater exposure than from a living patient. Regulations for cremation of exposed patients vary by state, as well as internationally, and there are no regulations at the federal level in the United States. We report radiation contamination at a crematorium.

A 69-year-old man with a pancreatic neuroendocrine tumor was treated with 193.6 mCi of intravenous lutetium Lu 177 dotatate at an Arizona hospital in 2017. The following day, he was admitted for hypotension at a different hospital and subsequently died from his underlying disease 2 days later. Treating physicians and the radiation safety department at the initial hospital were unaware of the unexpected death. The patient was cremated 5 days posttreatment. When the treating physicians and radiation safety officer became aware of the death, the crematorium was notified, and a survey of the empty cremation chamber and equipment was performed 1 month posttreatment using a Ludlum model 44-9 Geiger-Mueller detector. A RadEye spectroscopic personal radiation detector was used to identify the primary radionuclide. To investigate potential uptake of lutetium Lu 177 by crematory employees, a 24-hour urine sample was obtained from the crematory operator and analyzed by high-resolution gamma-ray spectroscopy, using deionized water as a control. The Mayo Clinic Institutional Review Board waived review for this report. Written consent for publication was obtained from the next of kin and the crematory operator.

Crematory equipment, including the oven, vacuum filter, and bone crusher, demonstrated a range of 5000 to 25 000 counts per minute with a 7.5-mR maximum exposure rate per hour on direct contact with the Geiger-Mueller detector. The personal radiation detector identified that radioactivity was primarily from lutetium Lu 177. There was no lutetium Lu 177 detected in the crematory operator’s urine. However, a different isotope, technetium Tc 99m, was detected with activity of 1.47 pCi per 24 hours. The crematory operator had never received technetium Tc 99m as part of a nuclear medicine procedure.

Radiation contamination at a crematorium was observed after cremation of a patient who was treated with lutetium Lu 177 dotatate. In addition, a trace amount of technetium Tc 99m was detected in the crematory operator. Given the contamination from this unexpected radioisotope, it is plausible that the crematory operator was exposed to volatilized technetium Tc 99m while cremating other human remains. Although other case reports^2,3 have described potential safety concerns following cremation of patients treated with radiopharmaceuticals, including yttrium Y 90 and iodine I 131, contamination of facilities has not, to our knowledge, been observed. Arizona has no regulation regarding informing crematoriums of deceased patients who have received a radiopharmaceutical. In contrast, Florida requires that no other material, including radionuclides, other than human remains shall be incinerated.⁴

Limitations include the single case, limited scope of the radiation survey, unknown clinical effects, and inability to quantify exposure from volatilized radionuclides. The annual air effluent concentration limits are 3 × 10⁻⁹ μCi/mL of lutetium Lu 177 and 2 × 10⁻⁷ μCi/mL of technetium Tc 99m if inhaled continuously for 1 year.⁵ Given the short range (1.5 mm) and half-life (6.65 days) of lutetium Lu 177 and the short half-life (6 hours) of technetium Tc 99m, the total effective dose equivalent annual limit of 1 mSv for members of the public, set by the Nuclear Regulatory Commission,⁵ was unlikely to have been exceeded. However, further studies are needed to evaluate the frequency and scope of radiation contamination and health effects of repeated or long-term exposure of employees in crematoriums in the United States, especially as the cremation rate was greater than 50% in 2017.⁶ Future safety protocols for radiopharmaceuticals should include postmortem management, such as evaluating radioactivity in deceased patients prior to cremation and standardizing notification of crematoriums.

Accepted for Publication: December 18, 2018.

Corresponding Author: Kevin L. Nelson, PhD, Department of Radiology, Mayo Clinic, 5777 E Mayo Blvd, Phoenix, AZ 85054 (nelson.kevin2@mayo.edu).

Author Contributions: DrsYu and Nelson had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Yu, Rule, Sio, Ashman.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Yu, Rule, Ashman, Nelson.

Critical revision of the manuscript for important intellectual content: Yu, Rule, Sio, Ashman.

Statistical analysis: Nelson.

Administrative, technical, or material support: Yu.

Supervision: Yu, Rule, Sio, Ashman.

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient’s family and the crematory operator for granting permission to publish this information.