An Image processing system (IPS) and related method and imaging arrangement (IAR). The system (IPS) comprises an input interface (IN) for receiving i) a 3D input image volume (V) previously reconstructed from projection images (π) of an imaged object (BR) acquired along different projection directions and ii) a specification of an image structure in the input volume (V). A model former (MF) of the system (IPS) is configured to form, based on said specification, a 3D model (m) for said structure in the input 3D image volume. A volume adaptor (VA) of the system (IPS) is configured to adapt, based on said 3D model (m), the input image volume to so form a 3D output image volume (V′).