A Doppler ultrasound system, comprising: an ultrasound probe configured to transmit an ultrasound beam through a bodily vessel for generating imaging data illustrative of an ultrasound image of a fluid flow through the bodily vessel; a vessel Fiber-Optic RealShape sensor configured to be introduced into the bodily vessel for generating sensing data informative of a reconstructed shape of the vessel Fiber-Optic RealShape sensor within the bodily vessel, relative to the ultrasound probe; a Fiber-Optic RealShape sensor controller configured to control a generation of the reconstructed shape of vessel Fiber-Optic RealShape sensor, an ultrasound probe controller configured to generate imaging data, from received ultrasound wave, illustrative of the ultrasound image of bodily vessel; characterized by a Doppler ultrasound controller being configured, in response to the generation o: the imaging data by the ultrasound probe controller and in response to the generation of the sensing data by the vessel Fiber-Optic RealShape sensor, to estimate a parametric relationship between the fluid flow through the bodily vessel and a transmission of the ultrasound beam through the bodily vessel by the ultrasound probe, based on a registration between the ultrasound probe and the vessel Fiber-Optic RealShape sensor, wherein the Doppler ultrasound controller is configured to estimate the parametric relationship from a shape of the bodily vessel as well as a position and an orientation of the bodily vessel within the ultrasound image from said sensing data and imaging data, and in that the Doppler ultrasound controller is further arranged to derive a Doppler measurement of the fluid flow through the bodily vessel from said estimation of the parametric relationship. an ultrasound probe configured to transmit an ultrasound beam through a bodily vessel for generating imaging data illustrative of an ultrasound image of a fluid flow through the bodily vessel; a vessel Fiber-Optic RealShape sensor configured to be introduced into the bodily vessel for generating sensing data informative of a reconstructed shape of the vessel Fiber-Optic RealShape sensor within the bodily vessel, relative to the ultrasound probe; a Fiber-Optic RealShape sensor controller configured to control a generation of the reconstructed shape of vessel Fiber-Optic RealShape sensor, an ultrasound probe controller configured to generate imaging data, from received ultrasound wave, illustrative of the ultrasound image of bodily vessel; characterized by a Doppler ultrasound controller being configured, in response to the generation o: the imaging data by the ultrasound probe controller and in response to the generation of the sensing data by the vessel Fiber-Optic RealShape sensor, to estimate a parametric relationship between the fluid flow through the bodily vessel and a transmission of the ultrasound beam through the bodily vessel by the ultrasound probe, based on a registration between the ultrasound probe and the vessel Fiber-Optic RealShape sensor, wherein the Doppler ultrasound controller is configured to estimate the parametric relationship from a shape of the bodily vessel as well as a position and an orientation of the bodily vessel within the ultrasound image from said sensing data and imaging data, and in that the Doppler ultrasound controller is further arranged to derive a Doppler measurement of the fluid flow through the bodily vessel from said estimation of the parametric relationship.