Abstract 13899: Radiation Exposure to Staff and the Public Following Myocardial Perfusion Imaging
Background Of all cardiac imaging tests, myocardial perfusion imaging (MPI) is unique in that patients may expose others to radiation after completion of the study. While the radiation burden to patients from MPI is established, few data are available regarding the secondary radiation exposure to those in close contact with a patient post-testing. We aimed to determine the potential radiation exposure to hospital personnel and to the public by patients post-MPI testing.
Methods We prospectively enrolled 27 inpatients (65±25 years, 67% men) referred for clinical exercise Technicium-99 (Tc-99m) sestamibi MPI. Using a Geiger-Mueller survey meter, we measured radiation exposure at the anterior chest and up to 2m following MPI at up to 4 hours following return to the hospital floor.
Results Patients were administered 0.38±0.03 Gbq Tc-99m at rest and 1.11±0.10 Gbq Tc-99m at stress. The radiation exposure decreased both with time, with an effective half-life of 4.5h, and with the inverse square of the distance. Immediately after injection, radiation exposure was 1.29±0.38 mSv/h at the chest wall, declining to 0.54±0.18 mSv/h at 5.56±0.55 h. Thus, close contact for 30 minutes within 1.5 hours after MPI, as with transthoracic echocardiography, would expose individuals to 0.32 to 0.53 mSv (at the elbow and chest, respectively). In contrast, at 1m and 2m from the patient, radiation exposure was <0.02 mSv/h at all time points (Figure).
Conclusions The radiation emitted by patients following clinical Tc-99m MPI, to which the public or hospital staff members may be exposed, is significant, particularly at close (<0.3m) distance to the patient and early (<1.5h) after radioisotope administration, and should be avoided. This risk of exposure of radiation to others highlights the importance of establishing guidelines for close patient contact and for test scheduling following MPI, especially for hospital personnel who are at increased risk for repeated exposures.
- © 2011 by American Heart Association, Inc.