新型聚合物凝膠劑量計DEMBIG之研究

The Study of A New Polymer Gel Dosimeter-DEMBIG Gel

姜繼宗(Chi-tsung Chiang)

指導教授 ： 謝栢滄

中臺科技大學/健康科學院/放射科學研究所/碩士(2010年)

摘要

聚合物凝膠劑量計是具有三度空間劑量分佈的量測工具，適合運用於放射治療中，作為劑量驗證工具。本研究主要在開發低毒性與高劑量反應的凝膠劑量計，以光學電腦斷層掃瞄儀（optical-computed-tomography，簡稱OCT）及核磁共振造影((Magnetic Resonance Image，簡稱MRI))兩項計讀方法做為凝膠劑量計定量量測。實驗第一部分為(1) 以DEMBIG凝膠為基礎配方，利用田口方法的原點直線式（zero-piont proportional）比較不同配方的劑量反應敏感度與線性度，尋找最適化的配方。(2) 以此配方進行劑量反應線性度、劑量反應穩定度、能量及劑量率依存性的探討。實驗第二部分為以磁振造影(MRI)做為凝膠劑量計定量量測，(1) 以DEMBIG凝膠最適配方，利用兩點法公式（two-piont method）計算凝膠反應值R2，尋找最適掃描參數。(2) 以MRI最適掃描參數進行DEMBIG凝膠劑量計臨床輻射特性之探討。(3) 驗證放射手術中心劑量之分佈。
本研究自製的DEMBIG gel劑量計重要成果分述如下:
一、 完成DEMBIG gel劑量計最適化配方之探討。
二、 完成DEMBIG gel劑量計以MRI量測工具最適參數之探討。
三、 完成DEMBIG gel劑量計使用兩套計讀工具(MRI、單點雷射凝膠計讀系統)在臨床輻射特性之探討。
四、 臨床放射手術劑量分布的驗證與治療計畫相比較誤差為3.9%(0-25Gy)。
五、 DEMA單體毒性低於其他凝膠劑量計，有潛力成為新型凝膠劑量計。

關鍵字

磁振造影 ； DEMBIG ； 聚合物凝膠劑量計 ； 最適方法

並列摘要

Polymeric gel dosimeters are being used to verify three-dimensional (3D) dose distributions of different types of radiotherapy treatments, especially the radiosurgery. The study of major in lowest toxic and high dose response of polymeric gel dosimeters and readout by optical computed tomography. The first year of the study is (1)using zero-point proportional of Taguchi method, when based on DEMBIG gel composition, found the optimal gel composition that has best sensitivity and linearity of dose response curve by difference gel composition. (2)To observe the dose response sensitivity, dose response stability, energy and dose rate dependency of the optimal gel composition, DEMBIG gel.
The second year of the study is (1) using two-point formulation, when based on optimal gel composition of DEMBIG, found the optimal scan parameter of MRI that has best sensitivity and linearity of DEMBIG gel. (2) Using optimal scan parameter of MRI to observe the properties of DEMBIG gel in clinical. The third purpose of the study is verify three-dimensional (3D) dose distributions of radiosurgery base on optimal gel composition and optimal scan parameter of MRI.

The results of this study were obtained：
1. The optimal gel composition of DEMBIG gel was established by Taguchi method.
2. Establishment of an single beam OCT system.
3. The optimal scan parameter of MRI was established.
4. Establishment of properties of DEMBIG gel in clinical.
5. The dose difference is 5% in three-dimensional (3D) dose distributions of radiosurgery.
The DEMBIG gel has lower toxicity in polymer gel dosimeter.

並列關鍵字

DEMBIG ； MRI ； Optimization method ； Polymer gel dosimeter

參考文獻

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Nature 166 146–7