Current Status of Stress Myocardial Perfusion Imaging Pharmaceuticals and Radiation Exposure in Japan: Results from a Nationwide Survey

Background: Ionizing radiation generated during medical imaging procedures is a matter of concern. However, the current status of radiopharmaceutical use in stress myocardial perfusion imaging (MPI) and the radiation exposure from these radiopharmaceuticals is unknown in Japan.

Methods And Results: A nationwide survey was conducted from June through July 2016. The questionnaires on the radiopharmaceuticals used and their administered doses during stress MPI were sent to 641 nuclear medicine facilities. The responses were collected from 431 facilities and the effective dose (ED) for an adult with standard body weight was calculated. Forty-three percent of the facilities used only TlCl, 35% used only Tc radiopharmaceuticals, and the remaining 22% used both. The two main reasons for using TlCl instead of Tc radiopharmaceuticals were "more familiarity with the usage of TlCl than Tc radiopharmaceuticals" and "apprehension about increasing the burden of physicians performing tracer injection twice." The mean ED was 14.0 ± 5.5 mSv (range, 3.9 to 25.2 mSv), which was higher than that reported in other countries.

Conclusions: The ED of stress MPI radiopharmaceuticals in Japan is probably higher than the world standard because more than 50% of the facilities still use TlCl. We recommend revising the routine stress MPI protocol to reduce the effects of ionizing radiation.