Strategies for accurate attenuation correction with single photon transmission measurements in 3D PET

Publisher Website
Google Scholar
Abstract
3D PET systems benefit from using single photon sources for transmission measurements as this reduces dead time and improves the photon flux, and therefore the signal-to-noise ratio, in the attenuation (CL) correction data. However, uncollimated point source measurements will include a large (/spl sim/50%) scatter component which biases the /spl mu/ values. No single approach will necessarily be able to mitigate against this for different scanning scenarios. The authors have investigated five approaches to scatter removal and/or correction using a /sup 137/Cs source for transmission data: (i) rescaling the measured data, (ii) energy window methods, (iii) restricting the polar acceptance angle (/spl theta/), (iv) collimating the source (ECAT ART only), and (v) segmentation and reassignment with expected /spl mu/ values. The results indicate that physical collimation of the ECAT ART point source and segmentation on the fixed ring EXACT 3D produce quantitatively useful data.