An improved HarshawTLD™ extremity dosimeter – DXTRAD beta ring

Abstract

An improved HarshawTLD™ extremity dosimeter system that is rugged in design and easy to wear is presented. This dosimeter is improved from the earlier version (2008) for personnel beta monitoring while still having full range photon performance. The dosimeter style, referred to as DXTRAD, is small in size and has identification by means of a circular barcode. It consists of a detector composed of a thin 7 mg cm −2 monolayer of HarshawTLD-700H ( 7 LiF:Mg,Cu,P) powder and a ring cap with a 3.3 mg cm −2 entrance window. The use of the TLD-700H TLD material provides a good beta energy response as well as a flat energy response from low energy x-rays to high energy gamma rays. A new assembly tool that improves the consistency of dosimeter geometry and ruggedness for warm and cold sterilization is also developed. With the optimized design, this dosimeter is capable of meeting the stringent energy and angular response requirements of the Physikalisch Technische Bundesanstalt (PTB) for both betas and photons. Presented in this paper are the ISO-12974 and PTB type tests as well as additional operational tests, such as residue, reuse, warm and cold sterilization, and environmental leakage.