Adequacy of annealing duration in reducing the background counts of personnel monitoring TLD cards: a study

A case study was undertaken to resolve the problem of high background counts of annealed TLD cards at one of the TLD Laboratory observed during handling the over exposure report (OER) received from various accredited laboratories for Non-DAE institutions. In order to verify the appropriateness of annealing procedures adopted by the Laboratory, a detailed study was conducted using four sets of cards exposed to various dose levels. It was found that inadequate annealing time than the standardized protocol duration of 4h at 230 deg C leads to larger standard deviation and enhanced background, which may slowly build up with repeated use and result in rejection of the dosimeter from field use. Hence it is recommended that annealing procedure of TLD cards must be strictly followed as per standardized protocol. (author)