本研究探討直線加速器治療時,由進行單次治療與一個月的治療時,造成治療室額外的環境劑量。利用熱發光劑量計,進行醫用直線加速器Elekta 6D Axesse的環境劑量測量。每月治療室環境劑量的偵測,利用TLD-100進行評估,單次治療的環境劑量偵測,利用TLD-100H進行評估,TLD-100及TLD-100H的校正使用6 MV的光子進行照射。每月治療室環境劑量測量,將TLD-100布於距離地板高度為280公分的天花板上,並進行一個月的環境劑量測量,前後進行3次的測量,評估其治療室每個月的額外環境劑量分布。單次治療室放射治療環境劑量測量,為利用一鼻咽癌體積調控旋弧治療,於腫瘤等高平面布TLD-100H劑量偵測點,並進行治療,前後進行三次治療,取三次結果平均,得到單次放射治療造成的治療室環境劑量。每月治療室環境劑量測量TLD-100布64個劑量測量點於治療室內及治療室門口,TLD-100H布82個劑量測量點於治療室內及低背景輻射實驗室,並討論其測量結果及熱發光劑量計TLD-100H之最小可測劑量(MDD)。於治療室內結果分析,利用二維劑量曲線圖及三維劑量曲線圖輔以表示,於TLD-100偵測治療室內每月環境劑量的結果,第一個月的劑量為2.97±0.05 Sv/mo,第二個月的劑量為3.32±0.02 Sv/mo,第三個月的劑量為3.44±0.05 Sv/mo。單次放射治療的環境劑量為0.42±0.07 Sv/fraction。TLD-100H最低可測劑量為0.60 mGy。
Environmental radiations of Axesse linac room at Medical University Hospital were assessed using Thermoluminescent dosimeters (TLD) during long time survey. TLD-100H and TLD-100 were calibrated using linac 6 MV photons. 82 measurement point of TLD-100H and 64 measurement points of TLD-100 were conducted for environmental monitoring. Environmental kerma rates were visualized using colored two-dimentional graphical representations during long time survey. Environmental radiations in treatment room were up to 2.97±0.05 Sv/mo, 3.32±0.02 Sv/mo and 3.44±0.05 Sv/mo. The environmental kerma in NPC radiation treatment were up to 0.42±0.07 Sv/fraction. The minimum detectable dose of TLD-100H was 0.60 mGy/fraction, respectively.