What term describes the process of generating a map of attenuation correction values for each pixel in a PET image?

The process of generating a map of attenuation correction values for each pixel in a PET image is termed a transmission scan. This involves using a source of radiation, often a radioactive isotope, to measure the attenuation of photons as they pass through the body. The data collected from this scan allow for the creation of a transmission map, which indicates how much the photons were attenuated by different tissues.

This attenuation map is critical for accurately reconstructing PET images because it corrects for the varying degrees of absorption of the emitted positron annihilation photons by the body's different tissues. When incorporated into the reconstruction algorithms, the attenuation correction improves the quantitative analysis and overall quality of the resulting PET images.

While the other terms listed refer to different reconstruction or imaging processing techniques, they do not define the process of generating attenuation correction maps specifically. Filtered Back Projection, for example, is a method for reconstructing images from projection data, while Maximum Likelihood Expectation Maximization and Ordered Subset Expectation Maximization are advanced iterative reconstruction techniques that utilize prior knowledge of the attenuation map but do not generate the map itself. Hence, the emphasis on transmission scan accurately represents the process in question.