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Fig. 3 | EJNMMI Physics

Fig. 3

From: Algorithms for joint activity–attenuation estimation from positron emission tomography scatter

Fig. 3

One iteration of joint estimation: an electron density estimate is used for attenuation correction in MLEM scatter-to-activity (step 1) and subsequent trues-to-activity (step 2) updates. Then, the activity distribution estimate is used as a source term in MLGA scatter-to-attenuation (step 3) and MLTR trues-to-attenuation (step 4) updates. In low-attenuation cases, only steps 2 and 3 are used in each iteration, while all steps are used in high-attenuation cases

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