Systems and methods for attenuation correction in time-of-flight (“TOF”) positron emission tomography (“PET”) imaging are provided. In some aspects, a provided PET system includes a plurality of detectors arranged about a bore configured to receive the subject, the plurality of detectors configured to acquire gamma rays emitted from the subject as a result of a radiotracer administered to the subject. The system also includes a data acquisition processor in communication with the plurality of detectors and configured to acquire TOF-PET data corresponding to acquired gamma rays. The system further includes an image reconstruction processor configured to process the acquired TOF-PET data with steps including estimating from the TOF-PET data, a posterior probability distribution of attenuation-corrected TOF-PET data, and reconstructing attenuation-corrected images from the posterior probability distribution of attenuation-corrected TOF-PET data. In some aspects, the image reconstruction processor is further configured to produce attenuation maps using the attenuation-corrected TOF-PET data.
