title: Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry.
abstract: An investigation has been made of glass beads and optical fibres as novel dosimeters for small-field photon radiation therapy dosimetry. Commercially available glass beads of largest dimension 1.5 mm and GeO2-doped SiO2 optical fibres of 5 mm length and 120 µm diameter were characterized as thermoluminescence dosimeters. Results were compared against Monte-Carlo simulations with BEAMnrc/DOSXYZnrc, EBT3 Gafchromic film, and a high-resolution 2D-array of liquid-filled ionization chambers. Measurements included relative output factors and dose profiles for square-field sizes of 1, 2, 3, 4, and 10 cm. A customized Solid-Water® phantom was employed, and the beads and fibres were placed at defined positions along the longitudinal axis to allow accurate beam profile measurement. Output factors and the beam profile parameters were compared against those calculated by BEAMnrc/DOSXYZnrc. The output factors and field width measurements were found to be in agreement with reference measurements to within better than 3.5% for all field sizes down to 2 cm2 for both dosimetric systems, with the beads showing a discrepancy of no more than 2.8% for all field sizes. The results confirm the potential of the beads and fibres as thermoluminescent dosimeters for use in small photon radiation field sizes.
authors.affiliation: Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK. Radiology Department, Faculty of Medicine, Kabul Medical University, Kabul, Afghanistan.
authors.forename: S M
authors.initials: SM
authors.lastname: Jafari
authors.forename: A I
authors.initials: AI
authors.lastname: Alalawi
authors.forename: M
authors.initials: M
authors.lastname: Hussein
authors.forename: W
authors.initials: W
authors.lastname: Alsaleh
authors.forename: M A
authors.initials: MA
authors.lastname: Najem
authors.forename: R P
authors.initials: RP
authors.lastname: Hugtenburg
authors.forename: D A
authors.initials: DA
authors.lastname: Bradley
authors.forename: N M
authors.initials: NM
authors.lastname: Spyrou
authors.forename: C H
authors.initials: CH
authors.lastname: Clark
authors.forename: A
authors.initials: A
authors.lastname: Nisbet
mesh_terms: D005336:Fiber Optic Technology / Q000295:instrumentation*; D005857:Germanium / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D006801:Humans; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D017785:Photons; D012822:Silicon Dioxide / Q000737:chemistry; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods; D014867:Water / Q000737:chemistry
chemical_list: D005857:Germanium; D014867:Water; C040516:germanium oxide; D012822:Silicon Dioxide