Report of a nationwide survey on actual administered radioactivities of radiopharmaceuticals for diagnostic reference levels in Japan

The optimization of medical exposure is one of the major issues regarding radiation protection in the world, and The International Committee of Radiological Protection and the International Atomic Energy Agency recommend establishing diagnostic reference levels (DRLs) as tools for dose optimization. Therefore, the development of DRLs based on the latest survey has been required for nuclear medicine-related societies and organizations. This prompted us to conduct a nationwide survey on the actual administered radioactivity to adults for the purpose of developing DRLs in nuclear medicine.

A nationwide survey was conducted from November 25, 2014 to January 16, 2015. The questionnaire was sent to all of the 1249 nuclear medicine facilities in Japan, and the responses were collected on a website using an answered form.

Responses were obtained from 516 facilities, for a response rate of 41 %. 75th percentile of ^99mTc-MDP and ^99mTc-HMDP: bone scintigraphy, ^99mTc-HM-PAO, ^99mTc-ECD and ¹²³I-IMP: cerebral blood flow scintigraphy, ^99mTc-Tetrofosmin, ^99mTc-MIBI and ²⁰¹Tl-Cl; myocardial perfusion scintigraphy and ¹⁸F-FDG: oncology PET (in-house-produced or delivery) in representative diagnostic nuclear medicine scans were 932, 937, 763, 775, 200, 831, 818, 180, 235 and 252, respectively. More than 90 % of the facilities were within the range of 50 % from the median of these survey results in representative diagnostic nuclear medicine facilities in Japan. Responses of the administered radioactivities recommended by the package insert, texts and guidelines such as 740 MBq (^99mTc-MDP and ^99mTc-HMDP: bone scintigraphy), 740 MBq (^99mTc-ECD and ^99mTc-HM-PAO: cerebral blood flow scintigraphy) and 740 MBq (^99mTc-Tetrofosmin and ^99mTc-MIBI: myocardial perfusion scintigraphy), etc. were numerous. The administered activity of many radiopharmaceuticals of bone scintigraphy (^99mTc-MDP and ^99mTc-HMDP), cerebral blood flow scintigraphy (^99mTc-HM-PAO) and myocardial perfusion scintigraphy (^99mTc-Tetrofosmin and ^99mTc-MIBI), etc. were within the range of the EU DRLs and almost none of the administered radioactivity in Japan exceeded the upper limit of SNMMI standard administered radioactivity.

This survey indicated that the administered radioactivity in diagnostic nuclear medicine in Japan had been in the convergence zone and nuclear medicine facilities in Japan show a strong tendency to adhere to the texts and guidelines. Furthermore, the administered radioactivities in Japan were within the range of variation of the EU and the SNMMI administered radioactivities.