Effects of x-radiation on fibreoptic endoscopes

Fibreoptic endoscopes exposed to x-radiation showed increased optical density of the fibre bundles with a reduction in light transmission. The length irradiated was important as well as the total dose, and there was a linear relationship between the dose/length product (Rm) and the loss of light transmission. The minimum light transmission acceptable for performing Endoscopic retrograde cholangiopancreatography (ERCP) was found to be 57% of that through an unused fibre bundle, and this degree of damage occurred after a total dose of 33.9 Rm. The radiation dose to the duodenoscope during ERCP examination was measured. The endoscope sheath was shown to have screening properties, with a transmission factor of about 30% for the Olympus JFB-1 and about 11% for the JFB-2 and JFB-3 instruments. The actual dose received by the fibre bundle of an Olympus JFB-2 duodenoscope was 0.084 R per ERCP and the mean dose-length product to the fibre bundle was calculated as 0.028 Rm per ERCP. Some degree of recovery of light transmission occurred while a duodenoscope was 'resting'. The expected life of a duodenoscope was estimated to be about 1200 examinations, but might be much less than this in units where greater radiations doses and longer exposures were used, and the endoscope was in constant use. Ways of minimising the radiation exposure during ERCP and prolonging the useful life of the duodenoscope are outlined. (author)