Changes in optic glass-fibers due to X-ray irradiation

The purpose of this study was to clarify the relationship between x-ray irradiation and changes in the functional properties of flexible fiberscopes. Scanning electron microscopy, electron spin resonance, and thermoluminescent dosimetry techniques were used to determine the nature of the changes and their possible reversibility. Decreases in light transmission were observed at exposures above 5 roentgens (R), color changes were observed above 25 R, and electron spin resonance absorption changes occurred above 100 R. These changes were proportional to the x-ray doses. The x-ray exposure rates of the segmental and the subsegmental bronchi are about 20 percent that of the patient's thoracic skin surface. The above-mentioned studies showed that, for optimal results, a fiberscope should not be exposed to more than 15 minutes of fluoroscopy by a TV apparatus per week.