Cover Imaging for Physicists

Iterative reconstruction: ML-EM

ESTRO Teaching Course Advanced Imaging: PET – Reconstruction, Contouring

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Iterative reconstruction

●

Discrete representation of data and image

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Expectation maximization (EM)

algorithm offers deter-

mination of

maximum likelihood (ML)

estimate of the image

Image space

Projection space

Current

image

estimate

Estimated

Projection

Measured

Projection

Forward

projection

Comparison

Error

Projection

Back-

projection

Update

estimate

Error

Image