Patient Specific Attenuation-Based Approach to Dosing of Rb82 for Cardiac (Dedicated) PET Perfusion Imaging.

134 Objectives While the radiation exposure to a patient (pt) undergoing Rest/Stress Rb82 PET perfusion imaging is low (~4 mSv), ALARA and management of total elution volume (TEV) of the Rb82 generator support lowering the dosing. The challenge is to lower the dose without impacting image quality. We examined the the ratio of the count rate of the (daily) transmission blank scan (TBS) to that of the pt attenuation-correction transmission scan (ACTS). Methods 45 consecutive PTS clinically referred for rest/stress Rb82 PET were enrolled and had 2 rest images performed. 1st a scan was the dosed according to the clinical protocol of the laboratory (a BMI-based dosing schedule. 2nd rest scan using attenuation based dosing (ABD) defined as follows: ABD=ACTS/TBS * correction factor (CF). CF was defined using historical PT scans. 3 CF values were used during the study and PTS were grouped by CF value into subgroup (SG) 1 (CF = 18.96), 2 (CF = 19.52) and 3 (CF = 20.36). All imaging was performed on a GE NxI PET scanner in 2D mode. BMI and ABD dosed rest scans were blindly reviewed for image quality using a 5-point scale (ranging 1 = non-diagnostic and 5 = excellent). Results The mean BMI=29.7±4.7, range 24.6 to 46.5. The mean rest dosage was 43.0 vs 35.6 for BMI & ABD respectively, p Conclusions Using the difference in count rate found on the pt ACTS and the TBS and a correction factor we were able to reduce the pt dose of Rb82 by 17.3% without impacting image quality across the entire BMI range. This method reduces radiation exposure and helps manage TEV.