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. The PCIT operates at 500mA current with real time current range from 90-100mA, dose rate of 3.03 MGy/hour and energy at 8.9KeV. The source to Source Surface Distance (SSD) was at 6.0 cm, with a field size of 20mm × 8mm diameter of a half circle. The TL response was measured using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader was obtained to a preheat temperature of 150 °C for 5 s, the output signal being acquired at a temperature ramprate of 35 °Cs-1, acquisition time of 10 s and a maximum temperature of 400 °C each of the FF samples. All reading was taken under N2 gas flow, suppressing oxidation and potential triboluminescence. The proposed FF shows the excellent TL response for high energy irradiation and good reproducibility and exhibits a very low rate of fading and low variation background signal. From these results, the proposed FF can be used as a radiation dosimeter in remote radiation sensing and favorably compares with the widely used of LiF based dosimeter on common medical radiotherapy application.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.