INDIVIDUAL MONITORING AND ITS QUALITY ASSURANCE USING THERMOLUMINESCENT CASO4DY TEFLON TAPE DOSIMETERS IN INDIA

CaSO4:Dy Teflon thermoluminscence dosemeters have been fabricated indi genously in continuous tape form. TL response of the tape dosemeters t o beta and gamma radiations has been studied as a function of the dose meter thickness to arrive at its optimum value. A single 80 mg.cm-2 th ick tape dosemeter (51 nun x 17 mm) along with a mica strip replaces t he earlier use of three 200 mg.cm-2 thick disc dosemeters for routine individual monitoring. The tape cards have been in field use for two a nd a half years. The performance characteristics of the cards under la boratory and field conditions are discussed. Dose computation algorith ms have been developed to give whole-body dose (mGy) and skin dose (mG y) for photons and beta radiation respectively from the TL outputs of three dosimetric elements under 1000 mg.cm-2 Cu+Al composite filter, 1 80 mg.cm-2 Perspex and an open region in a cardholder. Results of the Quality Assurance Programme, covering various TL monitoring stations i n India, are also presented. Based on ANSI criteria, only one outlier was observed over the past seven years.