2026-11-092026-11-09https://scholars.csmu.edu.tw/handle/123456789/38216In resent years, domestic medical center pushed to assemble medical electron linear accelerator (linac) in order to practice intensity modulated radiation therapy (IMRT). However, running linac will generate high energy neutrons, which will induce decay gammas. In this work, neutron field will be mapped for the Varian 21Ex (Varian Associates, Palo Alto, CA) of Chung Shan Medical University Hospital (CSMUH) which can produce 6 and 15MV x-ray. Neutron fluence were evaluated using 115In(n,γ)116mIn，及197Au(n,γ)198Au reaction as well as wrapped with Boron polyethylene (BPE) in the treatment room. The SAND II code will be utilized to check the various groups of neutron spectra. This work also identifies radioactive hot spots to which advisory for radiation protection can be assessed.國內各醫學中心近年來加快裝設醫用直線加速器，進行強度調控放射治療，惟運轉中的高能加速器會有巨量中子自靶區外釋，造成治療室的中子輻射場大幅增加，並衍生放射性核種，這些高達15MV的linac對病人重要器官，工作人員所造成的等價劑量預期將極為可觀，本計畫以始活化法(threshold foil activation analysis)度量中山醫學大學附設醫院放射腫瘤科，15及6 MeV的Varian 21Ex醫用直線加速器內中子輻射及劑量，利用金片及銦片產生的115In(n,γ)116mIn，及197Au(n,γ)198Au反應，進行不同照野下的佈點，再以硼套包覆金片及銦片來測量各中子群能譜，最後以美國醫學物理學會轉換因子來估計中子劑量及運用 SAND II程式驗證各群中子場分布，進而對醫學中心之加速器現場提出必要的輻射防護建議。Project