Individual Monitoring and Its Quality Assurance Using Thermoluminescent CaSO4:Dy Teflon Tape Dosemeters in India

CaSO4:Dy Teflon thermoluminescence dosemeters have been fabricated indigenously in continuous tape form. TL response of the tape dosemeters to ß and gamma radiations has been studied as a function of the dosemeter thickness to arrive at its optimum value. A single 80 mg.cm-2 thick tape dosemeter (51 mm x 17 mm) along with a mica strip replaces the 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 and a half years. The performance characteristics of the cards under laboratory and field conditions are discussed. Dose computation algorithms have been developed to give whole-body dose (mGy) and skin dose (mGy) for photons and ß radiation respectively from the TL outputs of three dosimetric elements under 1000 mg.cm-2 Cu+Al composite filter, 180 mg.cm-2 Perspex and an open region in a cardholder. Results of the Quality Assurance Programme, covering various TL monitoring stations in India, are also presented. Based on ANSI criteria, only one outlier was observed over the past seven years.