Disclosed are various approaches for generating synthetic computer tomography (CT) images using magnetic resonance imaging A patient body outline (PBO) of a patient is obtained. Then, a magnetic resonance image set in a limited field of view (MRI-in-LFOV) of the patient is converted into a synthetic computed tomography (CT) image set in limited field of view (syn-CT-in-LFOV) of the patient. Next, the syn-CT-in-LFOV is expanded to a synthetic CT image set in full field of view (syn-CT-in-FFOV) of the patient based at least in part on the PBO.