| Summary: | 碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 102 === Purpose:Except the NIPAM polymer gel, dose verification in radiotherapy can only be performed in two-dimension using other modern measurement tools. Although the NIPAM polymer gel analyzed by magnetic resonance imaging (MRI) is the only one tool that can measure radiation dose and perform in three-dimension, this technique is still limited in clinical department of radiation oncology without MRI scanner. Recently, computed tomography (CT) is developed to analyze the NIPAM polymer gel. That can improve the 3D radiation dose verification development in general department of radiation oncology. In this study, we used the CT scanner in our department to create the gel dose curve that can perform the relationship of the radiation dose and the density of polymer gel. Materials and Methods:We made intensity modulated radiotherapy (IMRT) plans in home-designed phantom. The dose verifications of these treatment plans will be performed by both MatriXX and the NIPAM polymer gel, and the dose differences with the treatment planning system was estemated. This study present the 3D measurement of dose distribution delivered using IMRT technique and NIPAM polymer gel with X-ray CT as the dose reading tool. The changes of dose response curve between one-field exposure vs multiple-field exposure and X-ray CT vs CBCT were also analyzed in this study. Results:The images acquired with X-ray CT are less noisy and with fewer artifact than those acquired with CBCT. The passing rate of Gamma Index (3%/3mm or 5%/5mm or 7%/7mm) in high dose region (80% prescribed dose) and medium dose region (30~80% prescribed dose) are all larger than 90%. The sensitivity of the dose response curve in one-field exposure is 0.503CTN/Gy, and would be improved to 0.667CTN/Gy in multiple-field exposure. Conclusion:The CT scanner is more convenient, which can be used to analyzed the NIPAN polymer gel and increase the potential of the NIPAN polymer gel used in dose verification in radiotherapy.
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