A binary image reconstruction method is provided to identify metal objects in a computer tomography (CT) image. The method includes providing a suitably programmed computer, providing a CT image, where the CT image includes intensity data, and the suitably programmed computer is used to determine a first range of attenuation coefficient values and a second range of attenuation coefficient values in the intensity data, where when a difference between the first range of attenuation coefficient values and the second range of attenuation coefficient values is less than a pre-determined gradient threshold value, a boundary of a metal object in the CT image is determined.