以三維光學電腦斷層掃描儀與聚合物凝膠劑量計驗證治療計畫

Using Three-dimensional Optical Computed Tomography and olymer gel dosimetry on dose verification

李佳駿(Jia-jing Lee)

指導教授 ： 張淵仁

中臺科技大學/健康科學院/醫學工程暨材料研究所/碩士(2012年)

摘要

放射治療技術發展迄今，如何確保放射治療時劑量的正確性與精確性，實為目前最為重要的課題。而目前商用之劑量驗證工具，大多為一維量測工具(游離腔ion chamber)或二維量測工具(底片Film), EPID, array of detectors等。對於近年來高劑量梯度、低能量但高線性治療設備(例如IMRT, TOMO, Cyber Knife)正子治療或是近接治療方式之劑量驗證，顯得捉襟見肘。
相較之下，凝膠劑量計擁有記錄全場三維劑量分佈之優勢，可以紀錄三度空間連續劑量分佈，尤其是凝膠劑量計(Gel dosimeter) 因空間解析度高，可使用多種劑量讀出工具計讀三維劑量分佈，因此是一項極具有潛力的劑量驗證工具。
本研究採用三維雷射光學電腦斷層掃描儀進行聚合物凝膠之掃描與三維劑量影像重建，並使用IMRT施予3*3cm2 , 5Gy之單區域照野治療計畫照射。採用的劑量計為使用NIPAM單體所製備之低毒性聚合物凝膠劑量計，假體尺寸為直徑ϕ10cm，高度為10cm。照射完畢後以三維雷射光學電腦斷層掃描儀對聚合物凝膠進行掃描，接著採用MATLAB進行三維劑量影像重建，最後與治療計畫進行劑量分佈驗證。
在本實驗結果顯示，以NIPAM聚合物凝膠進行單區域照野之劑量分佈與治療計畫劑量比較，以Gamma 評估法進行劑量評估，可以獲得DTA (Dose to agreement) 4mm，劑量誤差(dose difference percentage) 4%標準下97.6%通過率。另外，等劑量曲線圖也用來作比較分析。由凝膠劑量計量測得到的劑量分佈與治療計畫之劑量分佈相比較顯示60%以上之百分劑量曲線有高度吻合姓。由此顯示NIPAM 凝膠劑量計是極具潛力的劑量驗證工具，未來將有助於三維劑量驗證工具之發展。

關鍵字

凝膠劑量計 ； 三維影像重建 ； 雷射光學電腦斷層掃瞄儀 ； 放射治療 強度調控放射治療

並列摘要

In the development of radiation therapy, how to ensure the correctness and accuracy of a given dose in radiation treatment is still an important issue. Nowadays, all commercial dose verification tools are either one-dimensional, such as ion chamber, or two-dimensional such as Film, EPID, and array of detectors. In facing recently developing high-dose gradient treatment equipment, such as IMRT, TOMO, and Cyber Knife, proton therapy or brachytherapy treatment, it seems not to afford the requirement of dose requirement.

Oppositely, the gel dosimeter has the advantages of recording continuously three-dimensional (3-D) dose distribution. Especially, due to its high spatial resolution, gel dosimeter can be used for variety of read-out tools. Therefore, it is a very potential dose verification tool.

This study adopted a three-dimensional laser optical computed tomography (3-D OCT) scanner for the scanning of polymer gel dosimeter. And the three-dimensional dose reconstruction was performed after scanning. The IMRT was used as a radiation source to irradiate a single square field 3

並列關鍵字

IMRT ； laser optical CT scanners ； radiation therapy ； the gel dosimeter ； three-dimensional image reconstruction

參考文獻

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