| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2003: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
We investigate small field dosimetry for Stereotactic radiosurgery(SRS) and stereotactic radiotherapy(SRT), using a radiophotoluminescent glass dosimeter. We obtained the following results in this study.
1.Dosimetric properties of a radiophotoluminescent glass rod dosimeter(GRD) and the application of the GRD to small field dosimetry
We investigated dosimetric properties of a GRD regarding the uniformity and reproducibility of signal, dose linearity, and energy- and directional dependence, for high-energy photon beams. It was found that the GRD is superior to a thermoluminescent dosimeter(TLD) ; (1)unlimited repeatable reading, (2)excellent signal uniformity and reproducibility, (3)little fading, (4)excellent dose linearity, (5)little energy- and directional dependence. We also applied the GRD to the small field dosimetry in high-energy photon beams from a linear accelerator-based radiosurgery system, Gamma-Knife, and Cyber-Knife. It was found that the GRD is a very useful detector for s
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mall field dosimetry, in particular, below 10 mm circular collimator fields.
2.Development and the application of a radiophotoluminescent glass plate dosimeter(GPD) for small field dosimetry
We developed a prototype GPD system as a new device for small field dosimetry in high-energy photon beams, with Asahi Techno Glass Company. The size of the GPD is 30 mm square by 1 mm thick and it is made of the same material as a GRD. The GPD system can measure both the dose profiles and the absorbed dose simultaneously. This device has an advantage over the GRD, a film dosimeter, and other detectors at this point. The GPD can measure with high resolution, which is determined by a pixel size of a cooling type charge-coupled device(CCD) camera. The GPD can also read out with a range of 0.1-100 Gy. The accuracy of readout is about 0.8% and 0.5% on 1 standard deviation for 0.1 and 1 Gy, respectively. We applied the GPD to small field dosimettry and examined the usefulness. It was found the GPD system is a very useful detector for small field dosimetry, by comparing it to film and various detectors, and EGSnrc Monte Garlo simulations. Another purpose of this study is to apply more wide glass plate detectors to intensity modulated radiation therapy(IMRT) dosimetry. Less
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