應用同心圓搖擺機模擬呼吸狀態劑量分布的可行性評估

凝膠劑量計為相對劑量計之一，其優勢為可完整呈現三維劑量計讀結果。近來NIPAM凝膠劑量計發展極具潛力，在研究應用上有極穩定及準確的結果。應用動態假體模擬放射治療時體內器官位移是未來發展趨勢，對於肺部或上腹部腫瘤之劑量分布預估量測，及肺部立體定位放射治療手術之術前評估尤其重要。本研究應用同心圓搖擺機模擬呼吸狀態時的器官位移，使用NIPAM凝膠劑量計進行模擬肺部或上腹部腫瘤實際放射治療的情況，並利用MRI進行影像收集，後續應用MATLAB程式進行計讀分析。結果發現在模擬呼吸頻率為3秒⁄次，照野為4x4 cm^2的動態劑量曲線分布結果，100%劑量區與2x2 cm^2的TPS結果相似。此量測結果與臨床具有器官位移疑慮之放射治療計畫製作安全照射範圍界定原則一致，顯示NIPAM凝膠劑量計搭配動態假體模擬呼吸狀態劑量分布是可行的。

關鍵字

NIPAM凝膠劑量計；器官位移

並列摘要

Gel dosimeter is one of the ways to measure dosage relatively; its advantages are the only true 3-D dosimeters and at the same time a phantom that can measure absorbed dose distribution in a full 3-D geometry. Recently, there is a potential in developing NIPAM gel dosimeter, and applying it in research with consistency and accuracy. The application of dynamic phantom to simulate movement of internal organs during radiation therapy is the future trend. Therefore, dynamic phantom is important to the estimation of dosage distribution in lung or upper abdomen tumors as well as the evaluation of patient for SBRT of throax. This research applies concentric swing machine to simulate movement of organs while breathing; then uses NIPAM gel dosimeter to simulate the process of radiation therapy on lung or upper abdomen tumors. Images are collected using MRI and further analyzed using MATLAB. The result from the simulation has a respiratory period of 3 seconds / time, and its field is a 4x4 cm^2 curve showing dynamic dosage distribution. The result is similar between areas with 100% dosage and 2 × 2 cm^2 of TPS. The measurement results are consistent with and provide strong support for organ motion in clinical radiation therapy plans to help define regulation boundaries of radiation safety margin. This shows NIPAM gel dosimeter with dynamic phantom to simulate dosage distribution while breathingis possible.

並列關鍵字

NIPAM polymer gel dosimeter ； organ motion ； MRI

國際替代計量

應用同心圓搖擺機模擬呼吸狀態劑量分布的可行性評估

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