Irradiated glass and thermoluminescence yield: Dosimetric utility reviewed

https://doi.org/10.1016/j.radphyschem.2020.108680Get rights and content

Highlights

  • Review of thermoluminescence yield of doped glass media for dosimetric applications.

  • Focuses on radiotherapeutic regime, addressing the various challenges of modern practices in radiation dosimetry.

  • Origin of the underpinning defects emphasised.

Abstract

With numbers of efforts being made towards harnessing the thermoluminescence yield of doped glass media for dosimetric applications, predominantly in the radiotherapeutic regime, review is provided of the background to this, tracing developments leading to the present day. Included are an examination of the relative strengths of the various TLD currently on offer and that of glass fabrications, commercial Ge-doped optical fibre as well as novel fibres fabricated from Ge-doped glass. The demands that modern radiotherapeutic dose delivery systems are placing upon these passive forms of dosimetry are reviewed together with the various responses arising from current efforts. Also reviewed are the basis of the luminescence yield, citing the defect types occurring in silica, even in the absence of extrinsic dopants.

Introduction

Numerous applications in the health sector rely on controlled delivery of incident energy, present focus being on the harnessing of luminescence from irradiated glass-based dosimeters. Review is made herein of developments that have directly contributed to the thermoluminescence work that has been recently presented at ICDA-3 by the group of Bradley, exploring prospects for future utilisation of glass-based systems. Examples of prominent challenges include: tumour therapeutics, maximising target dose while preserving surrounding healthy tissue (IAEA, 2016); radiosurgery, offering fine-beam scalpel-like spatial acuity (to within 1 mm); image-guided radiology interventions; radionuclide theranostics, combining diagnosis and therapy. Apparent is the dependency on source type, configuration and collimation, the emissions interacting in tissue, thereby depositing dose. Of particular note are the several advances in dose delivery that are placing ever increasing demands on the systems of dosimetry; consider for instance accommodating the spatial resolution needs of say small field in vivo dosimetry in an aqueous medium at high dose-rates. The glass-based TL systems offer attractions that include the robust nature of the medium, their impervious nature both to water and the EMF of MRI-guided linacs, also acknowledging the high spatial resolutions that can be attained.

In the therapeutic regime, discrepancy in radiation delivered to the target can have highly adverse effects, the QA responsibilities being obvious. In this and other examples within radiation medicine, there is continuing need for enhanced accuracy and precision in the delivery and measurement of the optimum radiation dose. As with any other form of radiation dosimetry, developments towards utilising the luminescence yield of irradiated glass entails quantitative methods in determining the energy deposited within the medium (Attix, 1986).

Section snippets

Choices in dosimetry

In regard to the choices confronting the user, the many possibilities are far too great to cover in detail in any one short review. However, the more striking issues can best be illustrated through consideration of the most prominent of radiation monitoring devices, namely the ionization chamber (IC). The IC, regarded as the ‘gold standard’ quality assurance (QA) instrument throughout the realm of radiation medicine, utilizes relatively high voltages (i.e. several hundred or more), precluding

The luminescence of glass-based media

Media such as insulators and semi-conductors have the important ability to retain part of the absorbed radiation, metastable states being of the form of traps of electron-hole pairs, subsequently to be released (following stimulation) in forms that include infrared/visible light or ultraviolet (UV) light, otherwise referred to as luminescence. Luminescence comprises of the phenomenon of fluorescence and phosphorescence, both dependent on time delay between stimulation and light emission (Jarnet

The basis of Ge-doped SiO2 optical fibre TLDs

Ge-doped SiO2 optical fibres (also variously doped glass beads) are in active development, with numerous published TL investigations (see for instance, Benabdesselam et al., 2013a,b; Bradley et al., 2014; Jafari et al., 2014a, Jafari et al., 2014b; Nawi et al., 2015; Bradley et al., 2015, 2016). The basis of the luminescence is underpinned by molecular structure and composition, with the various associated trapping centres and activation energy reviewed by Bradley et al. (2012). SiO2, be it

Developments in fabrication of silica-based thermoluminescence dosimeters

As inferred, over the past three years we have been exploring the association between design and performance of silica-based media. Our efforts stemmed from the earlier adventitious use of commercially available Ge-doped single mode telecommunication fibres (SMF) in such applications, the design of these being entirely unrelated to the needs to which the fibres were put (see for instance, Hashim et al., 2010). The SMFs, as well as other telecommunication fibres such as multi-mode fibres (MMF,

The use of Ge-doped SiO2 optical fibre TLDs

The use of commercially available Ge-doped SiO2 optical fibres as dosimeters, with spatial resolution down to the order of 100 μm have been discussed by Rahman et al. (2012), representing a non-tissue equivalent Bragg-Gray cavity. The potential of Ge-doped SiO2 optical fibres and glass beads for particular application in small-field radiotherapy dosimetry has been researched by a number of authors (Benabdesselam et al., 2013a,b; Jafari et al., 2014a, Jafari et al., 2014b; Bradley et al., 2017;

Conclusions

The work represented herein is the result of a great many efforts by numbers of researchers; the glass fabrications work in itself derives from the work of a large collaborative group, centred on the University of Surrey and the University of Malaya. The push has been towards controlling the various influences and issues that guide the effective development of silica based media as TLDs. In particular, we have discussed fabrication issues and how these can influence defect types and

Declaration of competing interest

The authors have no conflict of interests to report.

References (53)

  • T. Kirby et al.

    Mailable TLD system for photon and electron therapy beams

    Int. J. Radiat. Oncol. Biol. Phys.

    (1986)
  • F. Moradi et al.

    Investigation on various types of silica fibre as thermoluminescent sensors for ultra-high dose radiation dosimetry

    Sens. Actuators A Phys.

    (2018)
  • N.M. Noor et al.

    Radiotherapy dosimetry and the thermoluminescence characteristics of Ge-doped fibres of differing germanium dopant concentration and outer diameter

    Radiat. Phys. Chem.

    (2016)
  • N. Ramli et al.

    Characterization of amorphous thermoluminescence dosimeters for patient dose measurement in X-ray diagnostic procedures

    Radiat. Phys. Chem.

    (2015)
  • Z.S. Rozaila et al.

    Ge and B doped collapsed photonic crystal optical fibre, a potential TLD material for low dose measurements

    Radiat. Phys. Chem.

    (2016)
  • L. Skuja

    Isoelectronic series of twofold coordinated Si, Ge, and Sn atoms in glassy SiO 2: a luminescence study

    J. Non-Cryst. Solids

    (1992)
  • N.H. Yaakob et al.

    Low-dose photon irradiation response of Ge and Al-doped SiO2 optical fibres

    Appl. Radiat. Isot.

    (2011)
  • E. Yoshimura et al.

    Optically stimulated luminescence of magnesium aluminate (MgAl2O4) spinel

    Radiat. Meas.

    (2006)
  • N.N. Zulkepely et al.

    Preliminary results on the photo-transferred thermoluminescence from Ge-doped SiO2 optical fiber

    Radiat. Phys. Chem.

    (2015)
  • F.H. Attix

    Gamma and X‐Ray Interactions in Matter, Introduction to Radiological Physics and Radiation Dosimetry

    (1986)
  • M. Benabdesselam et al.

    Performance of Ge-doped optical fiber as a thermoluminescent dosimeter

    IEEE Trans. Nucl. Sci.

    (2013)
  • D. Bradley et al.

    Doped silica fibre thermoluminescence measurements of radiation dose in the use of 223Ra

    Appl. Radiat. Isot.

    (2017)
  • R. Chen et al.

    Theory of Thermoluminescence and Related Phenomena

    (1997)
  • N. Chiodini et al.

    Optical transitions of paramagnetic Ge sites created by x-ray irradiation of oxygen-defect-free Ge-doped SiO 2 by the sol-gel method

    Phys. Rev. B

    (1999)
  • E. Dianov et al.

    Near-UV photosensitivity of germanosilicate glass: application for fiber grating fabrication

  • A. Entezam et al.

    Thermoluminescence response of Ge-doped cylindrical-, flat-and photonic crystal silica-fibres to electron and photon radiation

    PLoS One

    (2016)
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