Scatter correction for first-pass radiocardiography

The effect of the dual window scatter subtraction method was tested for first-pass radiocardiography using 99Tcm. The photopeak window of 126-154 keV (20%) and Compton window of 93-125 keV (30%) were used. The set of scattered images was multiplied by a factor of 0.4 and subtracted from the primary images. The size of the correction was tested by recalculation among a group of 16 patients sent for cardiac output studies for various reasons. The average of the percentage increase following correction was 4.0% (range -1.1 to 11.7%). The size of scatter correction was rather small in individual patients, but consistent for the group of patients as a whole. There was a statistically significant difference between the raw and corrected cardiac output values.