Which of the following reconstruction methods offers less noise and artifacts when compared to filtered back projection?

Ordered Subset Expectation Maximization (OSEM) is a reconstruction method commonly used in positron emission tomography (PET) that has been designed to address the shortcomings associated with filtered back projection (FBP). One of the critical issues with FBP is that it can produce noisy images and artifacts, particularly in regions with low counts due to the statistical nature of the PET data.

OSEM improves upon FBP by utilizing an iterative reconstruction process that optimally estimates the image from the acquired data. It does this by dividing the data into subsets and updating the image estimate in a manner that accounts for the statistical properties of the data being processed. This process results in a more refined image, with less noise and reduced artifacts, even in the presence of limited data. Additionally, OSEM can incorporate corrections for factors like attenuation and scatter, further enhancing image quality.

The other methods listed, such as Maximum Likelihood Expectation Maximization (MLEM), do offer improved quality over simple back projection, but OSEM is particularly noted for its efficiency in reducing noise when working with large datasets. Meanwhile, transmission scans are not directly comparable to these reconstruction techniques, as they serve a different purpose in the imaging process. MLEM, while effective, may be slower and