A method for generating a positron emission tomography (PET) attenuation correction map. The method includes obtaining a magnetic resonance (MR) image dataset of a subject of interest, obtaining a positron emission tomography (PET) emission dataset of the subject of interest, segmenting the MR image dataset to identify at least one object of interest, determining a volume of the object of interest, and generating a PET attenuation correction map using the determined volume. A medical imaging system and a non-transitory computer readable medium are also described herein