The reduction of unnecessary x-ray exposure during intraoral examinations

Abstract

A cone-collimating device that collimates the beam to a rectangle, eliminates plastic-pointer scatter, controls aluminum-filter and air scatter, and can be used with the techniques currently employed is described for use with dental x-ray apparatus. The cone is constructed of radio-opaque materials that collimate the primary beam to a rectangular field. The cone was designed in 2 parts; the proximal (round) part was made of 16-gauge steel tubing, 7.5 cm in dia, and the distal part of 18-gauge coldrolled steel. Rectangular collimation of the beam reduces the primary irradiated skin surface area by 36% from that of the 2.75-in. dia circular beam, so that the gonadal dose should be 55% less when the maxillary incisor area is irradiated. The metal cone effectively controls the aluminumfilter and air scatter outside the primary beam area. With the reduction in the volume of tissue irradiated, there is much less tissue scatter, and an appreciable improvement in the quality of film contrast was noticed. It was concluded that the use of a rectangular collimated field of 4.5 by 5.5 cm with a roentgen-opaque metal cone is a practical method for considerably reducing unnecessary exposure in periapical intraoral roentgenographic examinations. (TCO)