A novel supervised learning method to generate CT images for attenuation correction in delayed pet scans

•A reconstruction network is developed to convert PET raw data into pseudo PET image.•An elaborate network is designed to generate CT image for attenuation correction in PET image reconstruction. Inputs of the network are the two pseudo PET images in the first and delayed scan, and the CT image in the first scan. The network can output an estimated CT image in the delayed scan.•This method only requires one CT scan and therefore significantly reduces the X-ray radiation dose received by the patient in delayed PET imaging.