A filter for use in lateral cephalography

A new filter was devised for density compensation and absorbed-dose reduction in cephalometric radiographs. It is composed of a rare earth screen that plays a role in depicting soft tissue shadows and cephalometric points. The greatest reduction of the absorbed dose was about one seventh at the tube side of the thyroid gland when it was included in the direct x-ray beam. Smaller collimation was the most important factor in reducing the absorbed dose.