Glow Peak Analysis Of Pure And Ge-Doped Silica Flat Fiber At Ultra High Dose Electrons

Gentian silika leper (FF), dicadangkan sebagai pengesan asas dan novel bagi pengukuran sinaran untuk pendarkilau haba (PH) yang dihasilkan. Kajian ditumpukan kepada kesan tindakbalas PH bagi sampel FF dan keluk nyala bagi PH. Pemecut Linear (LINAC) digunakan bagi dos dalam julat radioterapi di antara 0.2 Gy-10.0 Gy, manakala pemecut elektron digunakan bagi dos yang teramat tinggi dalam julat 1 kGy sehingga 1 MGy. Tindakbalas PH terhadap dos, kesan bahan dopan, kesan kadar pemanasan dan parameter kinetik PH adalah dikaji. Didapati keluk nyala bagi FF beralih kepada suhu yang lebih tinggi, dengan peningkatan kadar pemanasan. Parameter kinetik menunjukkan kebergantungan dengan kadar pemanasan, bagi kedua-dua jenis FF samada tulin atau terdop Ge. Juga didapati model tenaga, Teori Kaviti Burlin (BCT) boleh digunakan bagi meramalkan tindakbalas tenaga FF dengan tepat. Silica flat fiber (FF) is being proposed as the basis for a novel radiation sensor of the thermoluminescence (TL) produced. The TL performance of the FFs and its respective glow curves were studied using a linear accelerator (LINAC) delivering doses of clinical radiotherapy within the range of 0.2-10.0 Gy. An electron accelerator (Alurtron®) was used to deliver the ultra-high dose. The TL dose response, dopant effect, heating rate effect and kinetic parameters of the deconvoluted glow peaks were investigated. The glow curve of FFs shifted to the higher temperature region as the heating rate increases. The kinetic parameters show dependence on the heating rate for both doped and un-doped FFs. It is found that the Burlin Cavity Theory (BCT) fit model can be used to predict the energy response of FF, accurately

Flat Ge-doped optical fibres for food irradiation dosimetry

Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%

Assessment of GeB Doped SiO2 optical fiber for the application of remote radiation sensing system

The research and development efforts on the silica (SiO2) optical fiber for application in radiation sensing and other dosimetry field have become quite active. The widely used LiF based dosimeter (TLD) has shown a relatively low reproducibility and there is a time delay in dose assessment which loses its capability as direct real-time dose assessment dosimeters unlike diodes. The macroscopic size of the optical fiber generally does not allow direct in vivo dose sensing in the inner organ for radiotherapy and medical imaging. A flat optical fiber (FF) with nominal dimensions of (0.08 x10 x 10) mm3 of pure silica SiO2 and GeO2 with Boron doped silica fiber SiO2 was selected for this research. The Germanium was used a dopant to enhance the flat optical fiber to reach much higher responsiveness and dose sensitivity in high energy and high dose irradiation. Together with this combination, both TLD dimension and dose assessment issues was hoped to be overcome. The research conducted by comparing the response of pure silica SiO2 flat optical fiber with a GeO2 with Boron doped silica SiO2 flat optical fiber. The FF sample was annealed at 400°C for one hour before irradiated. Kinetic parameters and dosimetric glow curve of TL response and sensitivity were studied with respect to the electron beam of high dose of micro beam irradiation of 1.0 kGy, 5.0 kGy, 10.0 kGy, 50.0 kGy, 100.0 kGy, 500.0 kGy, and 1.0 MGy using Singapore Synchrotron Light Source's (PCIT) beamline

Potential application of pure silica optical flat fibers for radiation therapy dosimetry

Pure silica optical flat fibers (FF) have been proposed as the basis for a novel radiation sensor by the measurement of the thermoluminescence (TL) produced. In this paper the TL performance of the FFs were studied. Using a linear accelerator (LINAC) delivering doses in the range 0.2–10.0 Gy, the TL dosimetric glow curves of the FFs were studied with respect to 6 MeV electron and 6 MV photon beams. When exposed to 6 MeV electron irradiation, the pure silica FFs displayed a supralinear response starting from 2 Gy up to 10.0 Gy. While for 6 MV photon irradiation, the FFs shows linear characteristic (f(D)=1) nearly up to 2 Gy. The TL intensity (Im) of the main peak of FFs is 1.5 times higher for 6 MeV electron beams than for 6 MV photon beams. The maximum peak temperature (Tm) it is not affected by the type of irradiation used at the same dose while the maximum TL intensity (Im) was found to be dependent on the type of radiation used. Overall results indicate that the pure silica FFs can be used as radiation sensors in the high-dose therapy dosimetry

Radioluminescence sensing of radiology exposures using P-doped silica optical fibres

In previous work we investigated the real-time radioluminescence (RL) yield of Ge-doped silica fibres and Al2O3 nanodot media, sensing electron- and x-ray energies and intensities at values familiarly obtained in external beam radiotherapy. The observation of an appreciable low-dose sensitivity has given rise to the realisation that there is strong potential for use of RL dosimetry in diagnostic radiology. Herein use has been made of P-doped silica optical fibre, 2 mm diameter, also including a 271 µm cylindrical doped core. With developing needs for versatile x-ray imaging dosimetry, preliminary investigations have been made covering the range of diagnostic x-ray tube potentials 30 kVp to 120 kVp, demonstrating linearity of RL with kVp as well as in terms of the current-time (mAs) product. RL yields also accord with the inverse-square law. Given typical radiographic-examination exposure durations from tens- to a few hundred milliseconds, particular value is found in the ability to record the influence of x-ray generator performance on the growth and decay of beam intensity, from initiation to termination

Thermoluminescence characteristics of flat optical fiber in radiation dosimetry under different electron irradiation conditions

Thermoluminescence (TL) flat optical fibers (FF) have been proposed as radiation sensor in medical dosimetry for both diagnostic and radiotherapy applications. A flat optical fiber with nominal dimensions of (3.226 × 3.417 × 0.980) mm3 contains pure silica SiO2 was selected for this research. The FF was annealed at 400°C for 1 h before irradiated. Kinetic parameters and dosimetric glow curve of TL response were studied in FF with respect to electron irradiation of 6 MeV, 15 MeV and 21 MeV using linear accelerator (LINAC) in the dose range of 2.0-10.0 Gy. The TL response was read using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader used includes; initial preheat temperature of 80°C, maximum readout temperature is 400°C and the heating rate of 30°Cs-1. The proposed FF shows excellent linear radiation response behavior within the clinical relevant dose range for all of these energies, good reproducibility, independence of radiation energy, independence of dose rate and exhibits a very low thermal fading. From these results, the proposed FF can be used as radiation dosimeter and favorably compares with the widely used of LiF:MgTi dosimeter in medical radiotherapy application