本部門為提昇放射線治療技術與醫療品質，新添乙部Siemens PRIMUS直線加速器（ 10/15 MV 雙光子能量），因空間及治療流程考量， 原鈷六十治療室（ LAI ）擬裝設移入原 LA Ⅱ之 6/10 MV 雙光子能量直線加速器，原鈷六十治療機則予移入隔鄰空間。 舊有按鈷六十能量（ LA Ⅰ）及 10 MV 光子（ LA Ⅱ）計算的屏蔽建構物， 包括屏蔽厚度、迷宮長度、鉛門設計…等，由於放射線能量提昇及空間重新規劃等因素，必須重新計算與評估。 本論文根據 NCRP49、51、33、102 號報告書及 ICRP60 號報告書與行政院原子能委員會游離輻射防護安全標準，考慮整體空間之主射束與二次輻射量及法規劑量限制後，需補強屋頂厚度、迷宮長度及鉛門厚度。計算的過程及相關屏蔽問題將在文中討論。

　　　　　For upgrade radiotherapy techniques and medical quality, our departmentreplaces Co-60 unit （ room LA Ⅰ） with the linear accelerator （ 6/10 MV dualenergy, moved from room LA Ⅱ） and set up an new Siemens PRIMUS linearaccelerator （ linac, 10/15 MV dual energy ） in LA Ⅱ. The Co-60 unit will moveto another compartment. Since the higher radiation energy of linacs and newarrangement of the treatment room, the previous shielding including thethickness of barriers and lead door, the length of maze....etc, need bere-evaluated. Calculations are based on NCRP49,51,33,102,ICRP60 and AEC doseconstraint, and the results show the shielding deficientcy on ceiling, maze andlead door. The process of the calculation and relative shielding problems willbe discussed in this paper.