Changes in the optic glass-fiber due to x-ray irradiation

Changes occur in the color of the image and the glass, if the fiberscope is frequently exposed over prolonged periods to x-irradiation. This problem may occur when x-ray are used to monitor the position of the fiberscope and its attachments. The purpose of this study is to define the relationship between x-ray irradiation and the morphologic properties and photochromatic transmission properties of the glass bundles of the flexible fiberscope. Special attachments were made for above studies. Scanning electron microscopy and electron spin resonance techniques were used to determine the nature of the changes and their reversibility. Comparative diagnostic x-ray dosimetry between the surfaces of the thorax and lumen of the tracheo-bronchial tree were accomplished by Thermoluminescent Dosimeters during thoracic fluoroscopy. Light transmission changes in the optic glass fiber were observed at more than 5 R, color changes were observed at more than 25 R and morphological changes were observed at more than 75 R of x-ray irradiation. Electron spin resonance absorption changes appeared in the optic glass-fiber at more than 100 R. The shape of these curves were proportional to x-ray dose. The irradiation dose to the skin in 1 minute, multiplied by three is equal to the irradiation dose to the segmental and subsegmental bronchus in 15 minutes by the results of comparative in vivo Radiation Dosimetry Study. For optimum results, 15 minutes of fluoroscopy by a TV machine a week is the limit of radiation doses to the same fiberscope by the results of above studies. (auth.)