2016_Imaging for Physicists

OSEM (ordered subset EM)

 Accelerated version of ML-EM  LOR data are partitioned in S disjoint subsets

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N J J , ,1 , ,   ⊂

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S

LOR

 Commonly, projections are divided into subsets with different views, or azimuthal angles  ML-EM algorithm for data from one subset only  Each subset processed in well-defined order  Convergence accelerated by factor ≈ S

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ESTRO Teaching Course Advanced Imaging: PET – Reconstruction, Contouring