The disclosure is related an apparatus and method for producing a panoramic radiograph of a target object using a three dimensional (3D) radiograph of the same object. The apparatus may include a communication circuit and a processor. The communication circuit may be configured to receive 3D radiograph digital data of the 3D radiograph. The processor may be configured to generate a plurality of x-ray projection images of the target object by performing forward-projection on voxels associated with the target object, and to combine the generated x-ray projection images to produce the panoramic radiograph of the target object.