A system for providing a live 3D image of a body lumen, comprising: a flexible surgical tool having attached thereto, at least one optic fiber with shape sensing sensors formed therein; at least one processor; an optics module operably connected to the at least one processor, and comprising a light source; an x-ray system comprising an x-ray source operably connected to the at least one processor; at least one memory operably connected to the at least one processor; and at least one program of instruction encoded on the at least one memory, the at least one program of instruction executable by the at least one processor to: interrogate the shape sensors using the light source in the optics module and determine the 3D shape of a flexible surgical tool in the body lumen using optical shape sensing, the body lumen being a blood vessel and the flexible surgical tool conforming to said blood vessel; take a 2D x-ray image of the body lumen using said x-ray system, at least one of said body lumen and said surgical tool being radiopaque; register the determined 3D shape of the flexible surgical tool to the x-ray image, wherein the registering step comprises segmenting a 2D image of the flexible surgical tool in the x-ray image and recovering the pose of the 3D shape of the flexible surgical tool relative to the x-ray source; and display the 3D shape of the flexible surgical tool with x-ray features from the 2D x-ray image super-posed thereon. a flexible surgical tool having attached thereto, at least one optic fiber with shape sensing sensors formed therein; at least one processor; an optics module operably connected to the at least one processor, and comprising a light source; an x-ray system comprising an x-ray source operably connected to the at least one processor; at least one memory operably connected to the at least one processor; and at least one program of instruction encoded on the at least one memory, the at least one program of instruction executable by the at least one processor to: interrogate the shape sensors using the light source in the optics module and determine the 3D shape of a flexible surgical tool in the body lumen using optical shape sensing, the body lumen being a blood vessel and the flexible surgical tool conforming to said blood vessel; take a 2D x-ray image of the body lumen using said x-ray system, at least one of said body lumen and said surgical tool being radiopaque; register the determined 3D shape of the flexible surgical tool to the x-ray image, wherein the registering step comprises segmenting a 2D image of the flexible surgical tool in the x-ray image and recovering the pose of the 3D shape of the flexible surgical tool relative to the x-ray source; and display the 3D shape of the flexible surgical tool with x-ray features from the 2D x-ray image super-posed thereon. interrogate the shape sensors using the light source in the optics module and determine the 3D shape of a flexible surgical tool in the body lumen using optical shape sensing, the body lumen being a blood vessel and the flexible surgical tool conforming to said blood vessel; take a 2D x-ray image of the body lumen using said x-ray system, at least one of said body lumen and said surgical tool being radiopaque; register the determined 3D shape of the flexible surgical tool to the x-ray image, wherein the registering step comprises segmenting a 2D image of the flexible surgical tool in the x-ray image and recovering the pose of the 3D shape of the flexible surgical tool relative to the x-ray source; and display the 3D shape of the flexible surgical tool with x-ray features from the 2D x-ray image super-posed thereon.