Remarkable reduction of exposure rate in patients with stress-only myocardial perfusion scan: let's safe mankind from unjustified radiation exposure

ABSTRACT

To measure radiation exposures rate in low-risk patients having stress-only and stress-rest myocardial perfusion imaging. This was a prospective study conducted from January 2012 till November 2012 upon patients with low pre-test probability for coronary artery disease [CAD]. A stress MPI [stress-only if MPI is normal and no resting study] followed by a resting MPI study [same day] if stress study was positive or equivocal. Exposure rates [in milli-Roentgen/hour, mR/hr] from injected patients at 1 meter distance were measured at 10 minutes, 1 hour and at time of releasing patients in both groups. Total 369 patients were included and 104 [28%] patients had stress-only and 265 [72%] had stress-resting studies. Mean administered [99m]Tc-MIBI dose in Stress-only and Stress-rest groups was 8 +/- 1 mCi and 24 +/- 03 mCi respectively [p<0.05]. Exposure rates[in mR/hr] within 10 min, 1 hour and at release time in Stress-only and stress-rest groups were 0.394, 0.294, 0.194and 1.540, 1.431, 1.207 respectively [p<0.05]. Mean stay of patients in laboratory was 90 +/- 39 minute in Stress-only and 156 +/- 53 minute in Stress-Rest group [p <0.0001]. There was a significantly widening gap between exposure rates from patients with Stress-only and stress-rest protocols as 2674%, 2179% and 1684% at 10 min, 1 hour and at time of release respectively. We conclude that adopting a Stress-only MPI protocol in low risk patients ensures significantly lower radiation doses to patients and technologists. A worldwide paradigm shift in nuclear cardiology practice would safe mankind from unjustified radiation exposure