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Proceedings Paper

Joint reconstruction of activity and attenuation with autonomous scaling for time-of-flight PET
Author(s): Yusheng Li; Samuel Matej; Joel S. Karp
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Paper Abstract

Recent research showed that the attenuation can be determined from emission data, jointly with reconstructed activity images, up to a scaling constant when utilizing the time-of-flight (TOF) information. We aim to develop practical joint reconstruction for clinical TOF PET scanners with autonomous scaling determination and joint TOF scatter estimation from TOF PET data, to obtain quantitatively accurate activity and attenuation images. In this work, we present a joint reconstruction of activity and attenuation based on MLAA with autonomous scaling determination. Our idea is to use a segmented region 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 imaging patient. All detectable LORs intersecting the unit media have an attenuation factor of e−1 ≈ 0.3679, i.e., the line integral is one. The scaling factor can then be determined by comparing the reconstructed attenuation image and the unit attenuation medium within the segmented known region(s). A three-step iterative joint reconstruction algorithm is developed. In each iteration, first the activity is updated using TOF OSEM from TOF list-mode data; then the attenuation image is updated using XMLTR—a modified MLTR from non-TOF LOR sinograms; a scaling factor is determined based on the segmented region(s) and both activity and attenuation images are updated using the estimated scaling. We implement the joint reconstruction with autonomous scaling, and evaluate using 3-D simulations. The joint reconstructions are also compared with the reference reconstruction with true attenuation image. In summary, we present a joint reconstruction of activity and attenuation with autonomous scaling. The scaling determination at each iteration allows the joint reconstruction to obtain a unique and faithful solution of activity and attenuation.

Paper Details

Date Published: 28 May 2019
PDF: 5 pages
Proc. SPIE 11072, 15th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, 110721H (28 May 2019); doi: 10.1117/12.2534849
Show Author Affiliations
Yusheng Li, Univ. of Pennsylvania (United States)
Samuel Matej, Univ. of Pennsylvania (United States)
Joel S. Karp, Univ. of Pennsylvania (United States)


Published in SPIE Proceedings Vol. 11072:
15th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine
Samuel Matej; Scott D. Metzler, Editor(s)

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