Estimated Effective Dose of Radiation among Non-radiation Workers in Cancer Institute Hospital of Japanese Foundation for Cancer Research

Background: In hospitals, patients injected with radiopharmaceuticals can serve as mobile sources of radiation. This study estimated effective doses for medical staff from these patients. Materials and Methods: Data regarding nuclear medicine and ultrasound examinations conducted at the Cancer Institute Hospital of Japanese Foundation for Cancer Research between January and June 2008 were recorded. Same-day examinations on the same patient were analyzed. Radiation doses of clinical laboratory technicians performing ultrasound examinations were measured as an example of non-radiation workers. Results and Discussion: Among 3,055 patients, 5,223 ultrasound examinations and 3,778 nuclear medicine examinations were conducted. Furthermore, 1,614 cases had both tests on the same day; 772 ultrasounds were performed during the 2-3 hours waiting period for drug accumulation, resulting in potentially substantial radiation exposure. Furthermore, 449 ultrasound examinations were conducted post-acquisition. Positron emission tomography examinations were frequent in the nuclear medicine department. Measurements obtained from 14 clinical laboratory technicians showed effective doses ranging from 0-0.3 mSv/mo; some staff recorded 0.1-0.2 mSv/mo. Upon annualization, eight of 14 (57%) technicians exceeded the public limit of 1 mSv/yr, and the maximum dose was 1.8 mSv/yr. Conclusion: This study estimated radiation doses for medical staff, focusing on clinical laboratory technicians as non-radiation workers. It revealed that some staff members experienced higher doses, even outside of radiation-controlled areas. Although the data is old, from 2008, without detailed records of individual clinical laboratory technicians, it is the only report of its kind in the world, and we look forward to further follow-up investigations.