Abstract
With continuous improvements in spatial resolution of positron emission tomography (PET) scanners, small patient movements during PET imaging become a significant source of resolution degradation. This work explores incorporation of motion information into expectation-maximization (EM) reconstruction algorithms. An important issue addressed is the existence of lines-of-response (LORs) corresponding to no actual pairs of detectors and their motion-induced "interaction" with the detectable LORs. An example of this is a scanner design with gaps existing in between the detector beads. It is shown that to properly account for such LORs in histogram-mode and list-mode EM reconstructions, in addition to motion correction of the events, the algorithms themselves must be modified. This modification is implemented by including motion-compensated sensitivity correction factors. We are able to demonstrate experimentally that the proposed approach resolves image artifacts that can appear when the conventional purely event-driven motion correction technique is used. An alternate image-space-based method for calculation of motion-compensated sensitivity factors is also derived, applicable in both histogram-mode and list-mode reconstruction tasks, which has the potential of being considerably faster in presence of frequent motion, especially in high-resolution tomographs.
Original language | English (US) |
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Pages (from-to) | 2588-2596 |
Number of pages | 9 |
Journal | IEEE Transactions on Nuclear Science |
Volume | 51 |
Issue number | 5 II |
DOIs | |
State | Published - Oct 2004 |
Externally published | Yes |
Keywords
- Expectation-maximization (EM) algorithm
- Histogram-mode
- List-mode
- Motion compensation
- Positron emission tomography (PET) reconstruction
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Nuclear Energy and Engineering
- Electrical and Electronic Engineering