Evaluation of Radiation-sensitive Composite Gels in Clinical Dose Verification

應用於臨床劑量驗證的輻射敏感性組合凝膠之評估

陳妍利(Yen-Li Chen) ； 謝栢滄(Bor-Tsung Hsieh) ； 徐惠麗(Huey-Lih Shyu) ； 謝玲鈴(Ling-Ling Hsieh)

《中華放射線技術學雜誌》 39卷1期 (2015/03) Pp. 46-51

摘要

本研究探討輻射敏感性組合凝膠經由輻射照射誘發化學變化，並搭配磁振造影量測技術作為三維凝膠劑量計可行性評估。比較兩種輻射敏感性組合凝膠-BANG®-3及NIPAM（N-isopropylacrylamid）在不同深度劑量差異性及採用伽瑪演算法計算伽瑪通過率。研究結果顯示商品化BANG®-3凝膠於不同深度之劑量差異為0.58%~5.68%，而客製化NIPAM凝膠則為0.31%~1.13%。另外，伽瑪演算法以3%/3 mm的可接受條件下評估劑量剖面的通過率，兩種凝膠在深度40 mm深度位置的通過率都可達到95%以上。在30 mm~70 mm的深度，伽瑪劑量通過率亦可保持在95%以上。然而BANG®-3凝膠由於容器邊緣產生氧擴散效應，抑制凝膠聚合反應現象較明顯，因此在容器邊緣附近劑量具較低通過率。研究結果發現客製化NIPAM凝膠與商品化BANG®-3凝膠均具有好的劑量準確性，適用於放射治療中例行性的三維劑量劑量驗證。

關鍵字

輻射敏感組合凝膠 ； 磁振造影 ； 伽瑪演算

並列摘要

Radiation-induced chemical changes in the radiation-sensitive composite gels used in three-dimensional dosimeters were investigated associated with magnetic resonance imaging (MRI) in this study. Dose accuracy was quantitatively evaluated to compare two radiation-sensitive composite materials using the gamma evaluation technique. Dose discrepancies at various depths were also evaluated. The dose differences varied from 0.58% to 5.68% for commercial BANG®-3 gel and 0.31% to 1.13% for NIPAM (N-isopropylacrylamide) gel. Gamma evaluation of the planar dose profile resulted in pass rates all exceeding 95% for BANG®-3 and NIPAM gels at 40 mm depth when 3%/3 mm acceptance criterion was used in the axial plane. Gamma pass rates over 95% were also maintained at depths of 30 mm to 70 mm for the two gels. However, BANG®-3 gel exerted a slight obvious oxygen diffusion effect through the container cap, inhibiting polymerization and thus, producing lower pass rate near the edge of container. The validation of NIPAM gel and commercial BANG®-3 gel confirmed their suitability for routine use in the three-dimensional dose verification of radiotherapy.

並列關鍵字

Radiation-sensitive composite gels ； NIPAM ； BANG® ； MRI ； gamma evaluation