A tunnel computerised tomographic scanner comprising: a supporting structure; a rotor supported by the supporting structure and rotatable relative to the supporting structure about an axis of rotation, the rotor surrounding a detecting zone through which the axis of rotation passes; a motor connected to the rotor for driving its rotation about the axis of rotation; an X-ray emitter mounted on the rotor; an X-ray detector mounted on the rotor, on an opposite side of the detecting zone relative to the X-ray emitter, the X-ray detector comprising at least one scintillator which has at least one emission face from which the scintillator emits light in the visible spectrum when it is struck by X-rays; an electronic processing unit connected to the X-ray detector and programmed to combine main images acquired by the X-ray detector, in a plurality of separate angular positions of the rotor around the axis of rotation, for reconstructing a three-dimensional structure of an object placed in the detecting zone; wherein: the X-ray detector also comprises a plurality of video cameras which are connected to the electronic processing unit, each video camera being positioned in such a way as to frame at least one portion of the scintillator, for acquiring one after another operating images, in the visible spectrum, of the respective portion of the scintillator; characterized in that: each of at least two separate video cameras of said plurality of video cameras substantially frame and detect light emitted from each zone of the at least one emission face of the scintillator, and the electronic processing unit is programmed to obtain each main image by combining all of the operating images obtained by the video cameras. a supporting structure; a rotor supported by the supporting structure and rotatable relative to the supporting structure about an axis of rotation, the rotor surrounding a detecting zone through which the axis of rotation passes; a motor connected to the rotor for driving its rotation about the axis of rotation; an X-ray emitter mounted on the rotor; an X-ray detector mounted on the rotor, on an opposite side of the detecting zone relative to the X-ray emitter, the X-ray detector comprising at least one scintillator which has at least one emission face from which the scintillator emits light in the visible spectrum when it is struck by X-rays; an electronic processing unit connected to the X-ray detector and programmed to combine main images acquired by the X-ray detector, in a plurality of separate angular positions of the rotor around the axis of rotation, for reconstructing a three-dimensional structure of an object placed in the detecting zone; wherein: the X-ray detector also comprises a plurality of video cameras which are connected to the electronic processing unit, each video camera being positioned in such a way as to frame at least one portion of the scintillator, for acquiring one after another operating images, in the visible spectrum, of the respective portion of the scintillator; characterized in that: each of at least two separate video cameras of said plurality of video cameras substantially frame and detect light emitted from each zone of the at least one emission face of the scintillator, and the electronic processing unit is programmed to obtain each main image by combining all of the operating images obtained by the video cameras. the X-ray detector also comprises a plurality of video cameras which are connected to the electronic processing unit, each video camera being positioned in such a way as to frame at least one portion of the scintillator, for acquiring one after another operating images, in the visible spectrum, of the respective portion of the scintillator; characterized in that: each of at least two separate video cameras of said plurality of video cameras substantially frame and detect light emitted from each zone of the at least one emission face of the scintillator, and the electronic processing unit is programmed to obtain each main image by combining all of the operating images obtained by the video cameras.