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In this paper we report about the demonstration of the nuclear track imaging capabilities of Ag-activated phosphate glass. A 375 nm laser and confocal laser scanning microscopy (CLSM) were respectively used for track excitation and detection. Specifically, the blue and orange radiophotoluminescent (RPL) tracks and dose distributions observed after irradiation with soft X-rays, gamma rays and heavy charged particles (HCPs) are examined. In addition, the origins of the reductions in RPL efficiency for high-dose X-ray irradiation and for irradiation with HCPs with high linear energy transfer (LET) values are investigated via a CLSM and a conventional fluorescent reader and discussed. © 2017 Elsevier B.V., Embargo Period 12 months

We investigate the physical and dosimetric characteristics of Ag-activated phosphate glass exposed to proton beams with various energies. We present time-resolved blue and orange radiophotoluminescent (RPL) spectra and examine the dependence of the peak wavelengths and RPL area intensities on gate time. Moreover, we consider various micro-scale 3D patterns written on Ag-activated glass by a focused proton beam and evaluate their orange and blue RPL axial-profiles using two-photon excitation microscopy. Finally, we discuss the remarkable broadening of the Bragg curve observed in Ag-activated glass and argue that it should be attributed to the saturation effect and/or non-linearity effect from the viewpoint of the relation between the dose delivered and the signal.

Silver-activated phosphate glass has long been used as passive-type solid state dosimeter for both individual and environmental dose monitoring. The principle is classified as radio-photoluminescence (RPL) whose mechanism is different from TSL and OSL. The RPL dosimeter has excellent characteristics such as stable sensitivity, negligible fading and reliable repeatability in radiation dose measurement. In Japan it is named “Glass Badge” and has come into wide use in individual dose monitoring services. In order to contribute to restoration of the contaminated area in Fukushima new-type glass dosimeters have been developed and the fruits of this work have led to various applications.

We investigate the characterisation and comparison of micro-scale patterns in silver-activated phosphate glass and lithium fluoride (LiF) single crystal written by a proton beam with an energy range of 1.7–4.5 MeV. A variety of micro-scale structures based on blue and orange luminescent Ag-related colour centres in Ag-activated glass and green and red luminescent F-aggregated colour centres in LiF are visualised by combining single- and two-photon confocal microscopes equipped with a blue continuous wave (cw) laser diode and a femtosecond (fs) laser in the near-infrared (NIR) region, respectively. Two- and three-dimensional (2D and 3D) reconstructed images are analytically evaluated using lateral/axial RPL intensity mapping. In addition, the origins of different RPL intensity profiles in a plateau region along the axial direction in both materials are examined and discussed.

We report the demonstration of a variable periodic time operated fibre-coupled dosimetry system using Ag-activated phosphate glass based on radiophotoluminescent (RPL) phenomenon. In order to overcome the inevitable “build-up” effect occurring in RPL glasses during and after X-ray irradiation, pertinent experiments are designed and carried out. The RPL intensities for four successive sequences, namely, the pre-dose, X-ray exposure, build-up and optical bleaching processes, are examined for the orange and blue RPL bands. Build-up curves and corresponding build-up rates are measured for different excitation wavelengths, analytically evaluated, and compared with those of a real-time fibre plastic scintillation dosimetry system. In addition, the orange RPL signal dependence on temperature and variable interval is examined for three successive sequences. The quick response of the dosimetry system developed here to the on/off switching operations is confirmed using seven successive sequences.

Silver-activated phosphate glass (Ag+-glass), which is commonly employed as a radiophotoluminscence (RPL) dosimeter, was applied as a fluorescent nuclear track detector (FNTD). The heavy ions from C to Fe ions were detected as fluorescent nuclear tracks under a confocal microscope. The detection linear energy transfer (LET) threshold was estimated to be 5 keV/μm in water. The fading effect was observed in which the fluorescent intensity decreases with repeated laser scans. The Ag+-glass has good potential applicability as the FNTD for the high LET range (5–200 keV/μm) in radioimmunotherapy and space radiation dosimetry uses.

Silver ion-activated phosphate glass (Ag+-glass) has a good potential for application to radiation dosimetry in various radiation fields due to its multifunctional properties as a detector. The Ag+-glass provides three independent signals of radiophotoluminescence, optical absorption, and nuclear track. The combination of these signals allows the dynamic range of the measured dose (10 μGy–10 kGy) and linear energy transfer ( 1 MeV/μm) to be widened.Silver ion-activated phosphate glass (Ag+-glass) has a good potential for application to radiation dosimetry in various radiation fields due to its multifunctional properties as a detector. The Ag+-glass provides three independent signals of radiophotoluminescence, optical absorption, and nuclear track. The combination of these signals allows the dynamic range of the measured dose (10 μGy–10 kGy) and linear energy transfer ( 1 MeV/μm) to be widened.

Ag-activated phosphate glass, which is the most commonly known radiophotoluminescent (RPL) material, has the capability to operate not only dosimeters but also two- and three-dimensional (2D and 3D) dose imaging detectors in the same host. This passive detector is based on radiation-induced, optically active nano-scale defects. In this work, the transient-state optical properties of the blue and orange RPL were investigated using a time-resolved spectrum technique for 137Cs and 60Co gamma-ray-irradiated Ag-activated phosphate glass. Specifically, the blue RPL intensity with a decay time of 5 ns as a function of the depth at the vicinity of the surface was systematically examined to clarify an accurate dose distribution within the glass. Moreover, a feasibility study into the use of an RPL Ag-activated phosphate glass detector for fluorescent nuclear track imaging was demonstrated using a confocal fluorescence image microscope for the first time.