Nor Haliza Yaakob

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

We have investigated the thermoluminescent response and fading characteristics of germanium- and aluminium-doped SiO(2) optical fibres. These optical fibres were placed in a solid phantom and irradiated using 6 and 10 MV photon beams at doses ranging from 0.02 to 0.24 Gy delivered using a linear accelerator. In fading studies, the TL measurements were continued up to 14 days post-irradation. We have investigated the linearity of TL response as a function of dose for Ge-, Al-doped optical fibre and TLD-100 obtained for 6 and 10 MV photon irradiations. We have concentrated on doses that represent a small fraction of that delivered to the tumour to establish sensitivity of measurement for peripheral exposures in external beam radiotherapy.

Thermoluminescence response of Ge- and Al-doped optical fibers subjected to low-dose electron irradiation

In this paper, we report quantitative features of the thermoluminescence (TL) responses of commercially available Ge- and Al-doped optical fibers subjected to low-dose electron irradiation. The TL response of Ge-doped optical fibers increases monotonically over the investigated dose range 0.02–0.24 Gy. The Ge-doped optical fibers have a greater response than the Al-doped optical fibers by a factor of at least 15. Results for the doped fibers are also compared with results for TLD-100.

Effective Atomic Number of Ge-Doped and Al-Doped Optical Fibers for Radiation Dosimetry Purposes

Optical fibers have been demonstrated by this group to show promising thermoluminescence (TL) properties with respect to ionizing radiation. Present research has focused on commercially produced single-mode telecommunication optical fibers manufactured by CorActive (Canada) either in the form of SiO2 optical fibers doped with either Ge or Al. Control of radiation dose is essential in performing an experiment in a biomedical context. One important aspect in this is the tissue equivalence of the dosimetric material. Mixtures or compounds that are similar in their radiation interaction characteristics to the soft tissue, bone or any other body constituents can be identified for this purpose. Effective atomic number of a medium prescribes its detection efficiency and tissue equivalence. To obtain the effective atomic number of the doped fibers, SEM (Scanning Electron Microscope) and EDXRS (Energy Dispersive X-ray Spectroscopy) analysis was performed to acquire the composition of the element inside the optical fibers. From our investigation, the value of Zeff is in the range of 11.5-13.4 and 11.7-13.7 for Ge-doped and Al-doped respectively (value of Zeff in soft tissue is 7.5 and Zeff for bone is between 11.6-13.8). Given that Ge- and Al-doped optical fibers are not soft-tissue equivalent, the assessment of dose deposition in such media would need to be corrected for an expected over-response. However, the value of Zeff is within the range of bone, making the optical fiber a strong candidate for use in skeletal radiation dosimetry.

Thermoluminescence energy response of germanium doped optical fibre using Monte Carlo N-particle code simulation

Over the last decade, the investigation of thermoluminescence (TL) dosimetry has expanded enormously. Many phosphor materials have been studied, become commercially available and have been applied to many areas of ionizing radiation dosimetry. This study is focusing on energy response of commercially available silicon dioxide optical fibre subjected to photon irradiation. The result obtained will be compared with energy response of TLD 100. The TL response of various photon energy, ranging from 20 keV to 6 MeV, was investigated as energy absorbed in the TL material. The study was carried out using Monte Carlo N‐Particle transport code version 5 (MCNP5). The inputs parameters include in this study are geometry specification, source information, material information and tallies. Tally F6 is use in this simulation. Even though the same pattern of response can be seen from each material, the simulation shows that the fibre optic had a greater response than TLD 100 in the lower energy ranges but slightly lower response than TLD 100 in the higher energy ranges.

Photon irradiation response on Ge and Al-Doped SiO2 optical fibres

Recently, research groups have reported a number of radiation effects on the applications of SiO2 optical fibres with possible use as dosimeter material because these optical fibre provide a good basis for medical radiation dosimetry. The objective of this study is to investigate the thermoluminescence response and fading characteristic for germanium and aluminium doped SiO2 optical fibres with photon irradiation. These optical fibres are placed in solid phantom and irradiated to 6 and 10 MV photon beam at dose ranging from 0.06 Gy to 0.24 Gy using Primus MLC 3339 linear accelerator at Hospital Sultan Ismail, Johor Bahru. In fading studies, the TL measurements were continued up to 14 days period. The optical fibres will produce glow curves whereby the information is then analyzed. Al and Ge‐doped optical fibres have a linear dose‐TL signal relationship that is proportionality between the TL signal and the doses. Comparison for TL response between different linear accelerator showed a good agreement becaus...