| Summary: | 碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 101 === Polymer gel dosimeters have characteristics of three-dimensional (3D) dose distribution and suitable to be used in radiation therapy dose verification. However, when the radiation dose is less than 1000 mGy, the polymerization reaction of the polymer gels are not proportional to the absorbed dose. Therefore, this study aimed to improve the use of high atomic compound polymer gel dosimeter sensitivity, and develop suitable diagnostic radiology of low-dose (mGy) polymer gel dosimeters.
In the study, we used NIPAM, MAGAT and BANG®-3 gel dosimeters doped with high atomic radiation sensitizer to compare sensitivity enhancement ratio with X-ray computed tomography, and investigated basic characteristics of various gel dosimeters via optical computed tomography. The results indicated when the irradiation dose ranges from 0 to 3.0 Gy, BANG®-3 gel dosimeter has lowest radiation sensitivity. The iodinated contrast agent was leads to maximum sensitivity enhancement ratio in different high atomic radiation sensitizer. However, the energy dependence was 11.11% in 120 kVp conditions. When irradiation dose ranges from 0 to 120.0 mGy, the sensitivity gains of NIPAM (5% (w/w) gelatin, 5% (w/w) NIPAM, 3% (w/w) bis-acrylamide, and 5 mM THPC) and MAGAT (4% MAA, 9% gelatin, and 10 mM THPC) gel dosimeters with 1.00 M iodine were 255% and 115%, respectively. Due to 5-5-3, 5 mM NIPAM gel dosimeter has the highest sensitivity gain and stability; therefore, NIPAM gel dosimeter was better than MAGAT gel dosimeter in low dose diagnostic radiation applications. In summary, it was found that 5-5-3, 5 mM NIPAM gel dosimeter can be used as an alternative conventional dosimeter for the determination three-dimensional dose distribution.
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