Low count density cardiac SPECT software and stress-only protocols significantly reduce technologist radiation exposure

1754 Objectives The 10 million myocardial perfusion (MPI) scans performed annually contribute significantly to technologist (tech) radiation exposure. A stress-only protocol obviates the resting MPI dose. New reduced count density software allows for reduction of injected activity (low-dose protocols) with preserved image quality. Both approaches should reduce patient (pt) and tech radiation exposure. Methods We estimated maximal tech exposure (for a difficult pt) for 4 different MPI protocols: standard 1-day rest(R)/stress(S) (9.5 - 13.2 mCi/ 32.0 - 39.2 mCi, mean 10.9 ± 1.2/34.9 ± 2.3 mCi); low-dose 1-day R/S (7.2 - 7.7 mCi/ 20.8 - 23.3 mCi, mean 7.5 ± 0.1/21.7± 1.0 mCi); standard 2-day S/R (22.9 - 23.4 mCi/ 23.0 - 23.8 mCi, mean 23.2 ± 0.2/23.4 ± 0.4 mCi); and standard S-only (21.4 -22.9 mCi, mean 21.9 ± 0.8 mCi). Our model assumed the tech has 5 min close contact with the pt during both the R and S studies, 1h after tracer injections, and then spends 10 min processing data, sitting at a computer close to the patient9s feet (without a lead shield). We measured the radiation levels with a Geiger-Mueller meter 6 times for each pt for both R and S MPI at the side of the imaging palette at the level of the pt’s thorax, 3 ft away from the thorax, and just distal to the pt’s feet. Results Mean exposure levels were: standard 1-day = 1.25 ± 0.44 mrad (n=9); 1-day low-dose = 0.91± 0.21mrad (n=15); standard 2-day = 1.25 ± 0.16 mrad (n=4); and S-only = 0.68 ± 0.11mrad (n=3). Exposures from the low-dose R/S and S-only protocols were significantly lower than the standard 1-day and 2-day protocols (p Conclusions Implementation of both low count density reconstruction software and a S-only protocol significantly reduce tech radiation exposure. In addition, conventional means to decrease exposure, i.e. briefer contact, increased distance, and lead shielding, should be encouraged.