Radiation Dosimetry for Cleft Palate Patients

Abstract

Cleft palate patients receive a considerable x—ray exposure in the course of diagnosis of many of the problems related to speech, dental, and medical study of their congenital anomalies. The x-ray dosage is a result of still films and cineradiographic studies. In addition, specialized laminagraphic and tomographic procedures are now being used. Additional radiation exposure occurs during and after cleft palate therapy. If the therapy is surgical in nature, postsurgical radiographic examinations are desirable to evaluate the efficacy of the procedure performed and to determine whether further surgery is indicated. When therapy is prosthetic in nature, cineradiographic examinations of the prosthesis are utilized (using television image orthicon fluoroscopy) during the impression-making and the fabrications stages and again after completion of treatment. In general, however, radiation exposure should be kept to an absolute minimum, consistent with the objective of obtaining the required diagnostic information. To this end, we have established the following radiographic procedure which incorporates as many precautions and safeguards as possible. Description of Equipment As shown in Figure 1, the basic radiographic equipment consists of 150 kv x-ray generator, and a heavy duty X-ray tube which is mounted on a ceiling-hung C-arm. The opposite end of the C—arm holds a high gain image intensifier with a coupled television image orthicon camera. The radiation field is limited by an adjustable collimator. Directly in front of the collimator is a thin ionization chamber which covers the entire radiation field. This is connected by means of a cable to a measuring and recording instrument in the control room (Figure 2)