Experimental Biology 2010: High Cumulative Radiation Dose Of Patients Undergoing Nuclear Myocardial Perfusion Imaging

Purpose of Study: The single medical diagnostic test with the highest radiation burden is myocardial perfusion imaging (MPI), which accounts for >10% of all radiation exposure to the U.S. population. Many patients undergoing MPI receive repeat tests or additional procedures exposing them to ionizing radiation, but no data are available on the total radiation burden. The purpose of this study is to characterize cumulative radiation doses and repeat testing of patients undergoing MPI.

Methods Used: This retrospective cohort study included 1097 consecutive patients undergoing index MPI. Two electronic health records systems were searched to identify all procedures performed before and after the index procedure. Effective dose of radiation from each procedure was estimated, based upon patient-specific information (e.g. administered activities of radiopharmaceuticals, kerma-air product) and standard conversion factors when available, else upon standard values for the type of study.

Summary of Results: Patients receiving index MPI underwent a mean of 23.9 procedures involving ionizing radiation; a mean of 6.5 were high-dose procedures (>3 mSv, the average annual background radiation in the U.S). These included a mean of 1.8 MPI studies per patient. 39% of patients had repeat MPI exams, including 5% of patients with ?5 MPI exams. Mean cumulative dose from MPI alone was 44.6mSv (median 28.9 mSv, range 6.5-407mSv). The mean cumulative effective dose from all medical testing was 96.5mSv, approximately equal to the maximal allowable radiation dose to nuclear industry workers over a 5 year period (median 64.0mSv, range 6.5-918mSv). 6% of patients received cumulative doses >100 mSv from MPI alone. 31% of patients received a cumulative effective dose for all medical sources of >100mSv, including 11% of patients with cumulative dose >200mSv.

Conclusions: Patients undergoing MPI typically receive many tests involving exposure to ionizing radiation and high cumulative dose. Repeat MPI testing is common. The benefits of medical imaging need to be weighed against radiation-associated risks. Development and validation of strategies that reduce the cumulative amount of radiation patients receive from medical testing, while ensuring that therapeutic decisions remain based on adequate diagnostic information, is essential.