Implementation and testing of the dual photopeak window scatter correction method on a multi-headed SPECT system

The authors describe the implementation and testing of the dual photopeak window (DPW) scatter correction method on a multiheaded single photon emission computed tomography (SPECT) system. The DPW scatter correction method assumes that variations in the ratio of counts within two abutted energy windows which span the photopeak region is due solely to changes in the scatter fraction, and that there is a unique relationship between the ratio and the scatter fraction which is stable with time and location across the face of the cameras. A small variation in the window count ratio was observed across the camera faces, with rotation, and with time. The regression relation between window count ratio and scatter fraction was determined to have significant variation with time and location across the camera faces at large scatter fractions. The method was observed to give significant improvement in the contrast of spheres in acquisitions of a SPECT phantom. The variation in the regression relations at large scatter fractions raises concern for the quantitative accuracy of the contrast improvement when the DPW method is applied to energy windows which split the photopeak at the emission energy