Assessment of scatter components in multispectral PET imaging

High resolution images in PET based on small individual detectors are obtained at the cost of poor sensitivity and significant scatter in the detectors. These drawbacks can be partially overcome by acquiring low-energy events and by using more efficient energy-dependent scatter correction methods. The feasibility of multispectral scatter correction was assessed by analyzing projection response functions measured in several energy windows to extract scatter components. While the fraction of well-positioned events drops from 90% in the photopeak region to less than 20% in the lower windows, the detector scatter fraction increases from 5% to 60% in the same range. By independent restoration of the latter component in every energy window, nearly 90% of all detected events can be recovered. Multispectral acquisition, therefore, is a promising approach for recovering sensitivity without loss of resolution in high resolution PET