Practical joint reconstruction of activity and attenuation with autonomous scaling for time-of-flight PET.

Practical joint reconstruction of activity and attenuation with autonomous scaling for time-of-flight PET. Phys Med Biol. 2020 Apr 27;: Authors: Li Y, Matej S, Karp JS Abstract Recent research showed that attenuation images can be determined from emission data, jointly with activity images, up to a scaling constant when utilizing the time-of-flight (TOF) information. We aim to develop practical CT-less joint reconstruction for clinical TOF PET scanners to obtain quantitatively accurate activity and attenuation images. In this work, we present a joint reconstruction of activity and attenuation based on MLAA (maximum likelihood reconstruction of attenuation and activity) with autonomous scaling determination and joint TOF scatter estimation from TOF PET data. Our idea for scaling is to use a selected volume of interest (VOI) in a reconstructed attenuation image with known attenuation, e.g., a liver in patient imaging. First, we construct a unit attenuation medium which has a similar, not necessarily the same, support to the imaged emission object. All detectable LORs intersecting the unit medium have an attenuation factor of e-1≈ 0.3679, i.e., the line integral of linear attenuation coefficients is one. The scaling factor can then be determined from the difference between the reconstructed attenuation image and the known attenuation within the selected VOI normalized by the unit attenuation medium. A four-step iterative joint reconst...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research