Scatter corrections for simultaneously acquired dual-isotope SPECT imaging using three windows

The authors investigated the feasibility of using a third energy window (EW) for rest /sup 201/Tl/stress /sup 99m/Tc scatter corrections in order to obtain improved quantification and image quality compared with dual-isotope myocardial perfusion imaging using two photopeak energy windows (PEWs). Three low energy ultra-high resolution parallel beam collimators were mounted on a triple-camera SPECT system and used to obtain planar and SPECT images. To obtain the relationships between the intermediate EW (IEW) and dual-isotope scatter EWs (SEWs), five different EWs, including an IEW (103 keV/spl plusmn/22%) between the dual-isotope PEWs, were used. Then, the scatter subtraction coefficients obtained from line source measurements with an anthropomorphic phantom were applied to the IEW's scatter correction. The IEW was used for the scatter correction for both isotopes. The crosstalk into each PEW measured with a cardiac phantom was similar in air; however, in water /sup 99m/Tc to /sup 201/Tl crosstalk was greater than twice of that in air. After attenuation and scatter compensation, the quantitative analysis and image quality were improved compared with dual-isotope imaging which used two PEWs, especially with /sup 201/Tl scans acquired in the presence of background activity. These results demonstrate that the IEW may be used for dual-isotope scatter compensation, and three window acquisition provides improved myocardial SPECT imaging in an anthropomorphic phantom.<
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