Investigation of silica-based TL media for diagnostic x-ray dosimetry

Abstract

We focus on the development of Ge-doped silica thermoluminescent dosimeters with sensitivity superior to that of the LiF (Mg,Ti) phosphors popularly used in x-ray diagnostic imaging dosimetry, the latter typically being referred to through use of the product identifier TLD-100. Of interest are Ge-doped silica telecommunication fibres (SMF) and tailor-made doped photonic crystal fibres (PCFc), the latter Ge-doped or also co-doped with boron. The PCFs are formed of capillaries that at high temperatures and under vacuum are made to collapse inwards (PCFc), the internal walls fusing and generating strain-related defects. To-date, the fabricated SMF, PCFc-Ge and PCFc-Ge-B have been observed to provide TL yields which weight-for-weight are some 2, 10 and 15x that of TLD-100. In present study we test the linearity of TL yield for x-ray doses from 0.1- to 10mGy, use being made of an x-ray tube operated at 80 kVp, an operating potential typically selected in chest radiography. For a dose of 10mGy, a study of energy dependence has been conducted using x-ray tube potentials of 80 kVp 100 kVp, and 120 kVp, with inherent filtration 0.9mm Al measured at 75 kVp, and total filtration of 2.8mm Al at 80 kVp.