1. A method of determining a local patient dose applied to a patient in a diagnostic computed tomography scan of an area of interest of the patient, the method comprising the steps of: segmenting an image of an area of interest of the patient, wherein the image of the area of interest is determined from scan data obtained in the diagnostic computed tomography scan; determining a fluence map on the basis of the image of the area of interest; and using the segmented image and the fluence map to determine a dose image showing local patient doses applied to the patient in the scan.