Abstract: A method for dimensional measurement of a vessel (100) of a subject that is a bodily fluid-conducting vessel comprising: receiving image data comprising a three-dimensional medical image containing the vessel; obtaining from the image data an image patch (130) that is a two-dimensional image containing a transverse cross-section of the vessel (100); generating from the image patch (130), a set of rays (R1 to RX), wherein each ray (R1 to RX) is a straight line, one end contacting a centre point (140) of the outer footprint (150) of the vessel (100) and at the other end extending beyond the outer footprint (150) of the vessel (100), wherein each ray (R1 to RX) has a different direction; determining for each ray (R1 to RX) an image intensity profile of the image patch (130) along the ray as a function of distance from the centre point (140); determining from the image intensity profile along each ray (R1 to RX), one or more of a ray wall thickness (RXwt), a ray lumen radius (RXlr), a ray outer radius (RXor); det