The Potential of Doped Silica Telecommunication Fibre as a 1-D Detector for Radiation Therapy Dosimetry
A. T. Abdul Rahman 1,2, D. A. Bradley 1, A. T. Abdul Rahman 1*
1 Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH Surrey, UK
2 Schools of Physics and Material Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Campus of Negeri Sembilan, 72000 Negeri Sembilan, Malaysia
This work encompasses dosimetric studies of Ge-doped silica telecommunication fibre as a 1-D thermoluminescence (TL) system for therapeutic applications. The therapy modalities used are a superficial X-ray beam therapy facility, a synchrotron microbeam facility and an electron linear accelerator, covering the energy range from a few KeV to several MeV. The irradiations made included 90 kVp X-ray exposure delivered by a superficial X-ray unit, synchrotron radiation delivered at a mean energy of 109 keV and electron and photon beam irradiations delivered by an electron linac (9 - 20 MeV electrons and accelerating potentials of 6 - 15 MV for photons). The commercially available Ge-doped silica optical fibre dosimeter has been characterised. The dosimetric characteristics of includes, reproducibility, fading, dose response, reciprocity between TL yield and dose-rate and energy dependence. The commercially available Ge-doped silica optical fibres were subsequently found to produce a flat response to fixed photon and electron doses to within better than 3% (S.D) of the mean of the TL distribution. Also observed was that irradiated Ge-doped silica optical fibres only gave rise to small signal fading, with an average loss of TL signal of ~0.2% per day. In addition Ge-doped silica optical fibres have been also demonstrated to provide good reproducibility and reusability. In term of dose response, Ge-doped silica optical fibres have been shown to provide good dose response linearity from a fraction of 1Gy up to 2 kGy covering a comprehensive range of photon sources, from the traditional bremsstrahlung sources generated at kilovoltage to megavoltage potential, through to a synchrotron X-ray source applied in microbeam radiation therapy (MRT) investigations. Following understanding of the dosimeters characteristic from these characterisations, the dosimeters were tested in measure photoelectron enhancement from iodinated contrast media as might be applied in radiation synovectomy. Initial study of interface radiation dosimetry concerned measuring the dose enhancement that results from use of iodinated contrast media, demonstrated that Ge-doped silica optical fibres provide high sensitivity and the ability to measure the significant dose enhancement when using iodinated contrast media. The TL yields have been found to be some 65% greater in the presence of iodine than that obtained in its absence, measured in polyurethane and PMMA media. This study had successfully demonstrates the capabilities of the dosimeters investigated in various applications in radiation therapy dosimetry.
Abdul Rahman, A. T., Bradley, D. A., Doran, S. J., Thierry, B., Bräuer-krisch, E. & Bravin, A. 2010a. The Thermoluminescence Response of Ge-doped Silica Fibres for Synchrotron Microbeam Radiation Therapy Dosimetry. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors And Associated Equipment, 619, 167-170.
Abdul Rahman, A. T., Nisbet, A. & Bradley, D. A. 2010b. Dose-rate and the Reciprocity Law: TL Response of Ge-doped Sio2 Optical Fibers at Therapeutic Radiation Doses. Nuclear Instruments and Methods In Physics Research Section A: Accelerators, Spectrometers, Detectors And Associated Equipment, In Press, Corrected Proof.
A.T. Abdul Rahman, R.P. Hugtenburg, Siti Fairus Abdul Sani, A.I.M. Alalawi, Fatma Issa, R. Thomas, M.A. Barry, A. Nisbet, and D.A. Bradley. An Investigation of the Thermoluminescence of Ge-doped SiO2 Optical Fibres for Application in Interface Radiation Dosimetry. Abstract submission and presented at 8th IRRMA conference in Kansas City, United State of America, 26th June – 1st July 2011.
Fatma Issa, A.T. Abdul Rahman, R.P. Hugtenburg, D.A. Bradley and A. Nisbet. Ge-doped optical fibres as thermoluminescence dosimeters for LDR I-125 brachytherapy sources. Abstract submission and presented at 8th IRRMA conference in Kansas City, United State of America, 26th June – 1st July 2011.