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Three-gamma annihilations as a new modality in PET

We argue that the positron annihilations into three photons, although quite rare, might still be used as a modality in positron emission tomography imaging. This is possible, because the amount of information gained when the three decay photons are detected is significantly larger than in the case of 511 keV two-gamma annihilation. Feasibility and performance of the new technique is assessed by numerical calculations. Examples of three-gamma images obtained in Monte Carlo simulations are presented.