An x-ray system comprising an x-ray source, a single essentially round collimator, a camera, a detector and a monitor, means for moving the collimator in a plane generally parallel to the plane of the collimator and the collimator comprising a central aperture that allows all the radiation to pass through, an outer annulus that reduces the radiation passing through at an amount depending on the material and the thickness of the material and an inner annulus between the central aperture and the outer annulus, with thickness changing as a function of the distance from the center, starting at thickness zero on the side of the central aperture and ending at the thickness of the outer annulus on the side of the outer annulus.
