Aim: A new strategy is introduced for a double-head gamma-camera to calculate and to correct for attenuation distribution from count rates of backscattered radiation of 99mTc in the human thorax/myocardium setting. The intention was to gain segmented and calibrated images of distribution employing the structures of lungs and other tissues, so that attenuation may be subsequently corrected by the method of Chang
Methods: Acquisition was done simultaneously in three energy window for 99mTc to receive both emitted and scattered radiation. The acquire projections were used to calculate the attenuation distribution and to execute a scatter correction by the method of Ogawa et. al. By measuring phantoms and evaluating a set of patient studies, quality for both of the approaches towards attenuated distribution and the quality of attenuation correction was tested and an optimal setting for parameters involved was selected.
Results: The procedure adequately approaches the correction for both emitted and scattered radiation in SPECT, as experienced in phantom and patient studies. Clinical usefulness was preliminary documented in selected cases. In normal perfusion, distribution was more homogeneous. Perfusion defects appeared more definitive. Problems occurred in high adjacent non-target activity (e.g., in the gallbladder) and with low count rate statistics.
Conclusion: Myocardial 99mTc MIBI SPECT may be effectively corrected for both attenuation a scatter without an additional transmission device.