Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Time efficient scatter correction in Time-Of-Flight PET image reconstruction
We are currently modifying our previously developed Tube of response High resolution OSEM Reconstruction (THOR), see ref , to make full use of the available Time-of-Flight (TOF) information. The most critical point in this context is accurate and computational efficient TOF Scatter Correction (TOF-SC). Here, we report on our approach to solving this issue.
Four different, partly newly developed approaches to estimation of scatter time distribution have been investigated: A. Simple scatter scaling: this approach assumes that scattered and unscattered events have identical time distribution within each single LOR. B. Attenuation based SC (new approach): in this approach the object is modeled as a set of “scatter points”. Each scatter point is also assumed to be a scatter source. C. Attenuation and activity based SC (new approach): in this approach a small set of “emission points” for approximation of the given activity distribution is introduced. Calculations are similar to B except that scatter sources are determined as projections of emission points onto straight lines connecting selected scatter point and detectors. D. TOF-SSS Time-Of-Flight extension of Single Scatter Simulation by Watson.
All four approaches have been integrated into THOR and tested in dedicated phantom and patient studies. Approach A does not yield quantitatively correct scatter distributions for big objects. Approach B is superior to A but notable artifacts remain in the presence of high-contrast. Approach C is able to eliminate part of these artifacts but requires more computation time. Approach D is the most accurate and computationally most expensive.
Our preliminary results indicate that attenuation based SC might be the best compromise between computation time and image quality for a wide range of applications.
 A. Lougovski, F. Hofheinz, J. Maus, et al., Physics in Medicine
and Biology 59(3), 561 (2014)
Keywords: PET; TOF-PET; Scatter Correction; TOF-SC
NuklearMedizin 2017, 26.-29.04.2017, Dresden, Germany