Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a 60Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium.

No abstract

Using tailor-made sub-mm dimension doped-silica fibres, thermoluminescent dosimetric studies have been performed for α-emitting sources of RaCl (the basis of the Bayer Healthcare product Xofigo®). The use of RaCl in the palliative treatment of bone metastases resulting from late-stage castration-resistant prostate cancer focuses on its favourable uptake in metabolically active bone metastases. Such treatment benefits from the high linear energy transfer (LET) and associated short path length (<100µm) of the α-particles emitted by Ra and its decay progeny. In seeking to provide for in vitro dosimetry of the α-particles originating from theRa decay series, investigation has been made of the TL yield of various forms of Ge-doped SiO fibres, including photonic crystal fibre (PCF) collapsed, PCF uncollapsed, flat and single-mode fibres. Irradiations of the fibres were performed at the UK National Physical Laboratory (NPL). Notable features are the considerable sensitivity of the dosimeters and an effective atomic number Z approaching that of bone, the glass fibres offering the added advantage of being able to be placed directly into liquid. The outcome of present research is expected to inform development of doped fibre dosimeters of versatile utility, including for applications as detailed herein.

No abstract

In this paper we report, the characteristics of PTTL after irradiation with 60Co gamma rays as a function UV light exposure wavelength, gamma irradiation dose, and UV light exposure time were determined for Ge-doped SiO2 optical fibers. The efficiency of dose reassessment for this fiber was compared to standard thermoluminescence detector, TLD100. Experiments show that the method works well with the UV lamp of 254 nm within region of doses between 3 to 50 Gy, but could be applied for higher and lower doses as well. The effect of exposure time of UV radiation on the PTTL signal was studied from 5 to 120 minutes to determine the highest sensitivity and the limit of the dose. The efficiency of dose reassessment with 10 Gy of gamma irradiation expose to UV light for 15 minutes relative to PTTL values of about 27.0% and 2.3% for Ge-doped SiO2 optical fiber and TLD100.