I. Introduction
Small field of view detectors based on position sensitive photomultiplier tubes (PSPMTs) coupled to pixelized scintillators offer improved spatial resolution compared to the standard Anger camera and have been used in the last decade in dedicated small field of view (FOV) systems for single photon emission computed tomography (SPECT) [1], [2]. Their main applications are planar and tomographic imaging of small animals in the laboratory environment and clinical scintimammography for the early detection of small breast tumors [3]. However, SPECT images still suffer from low contrast as a result of photon scatter, which affects the quantification of SPECT images [4]. The standard method for excluding the scatter component in pixelized scintillators is the application of an energy window around the central photopeak channel of each crystal cell, but small angle scattered photons still appear in the photopeak window and they are included in the reconstructed images. A number of scatter correction techniques [5]–[10] have been proposed in order to estimate the scatter component. These techniques have not yet been applied in pixelized scintillators, where most groups use the standard one-photopeak window for scatter correction. Furthermore, scatter correction is applied not only to phantom but to animal experiments as well. In this paper, we have assessed three subtraction techniques that use a different approach in order to calculate the scatter component and subtract it from the photopeak image: the dual energy window subtraction technique (DEWST), the convolution subtraction technique (CST), and a deconvolution technique (DT). All techniques are compared to the standard method. Such a comparison based on real data has yet to be published.