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目的对医科达生产的6、10、15 MV高剂量率医用电子加速器机房的主要屏蔽体防护核算进行探讨。方法根据《放射治疗机房的辐射屏蔽规范第2部分:电子直线加速器放射治疗机房》(GBZ/T 201.2-2011)等提供的有关方法进行防护核算。结果 10 MV 2200 cGy/min和15 MV 600 cGy/min X射线对某一加速器治疗室主屏蔽(如北墙)厚度应分别为2590、2624 mm;对副屏蔽(如南墙)厚度应分别为1240、1138 mm;散射角20°时,10、15 MV X射线经患者一次散射对北墙主屏蔽直接相连的次屏蔽区(厚度1840 mm)的周围剂量当量率分别为4.89、3.05μSv/h;防护门应至少为110 mm含硼5%聚乙烯(内层)和17 mm Pb(外层)。结论对医科达生产的6、10、15 MV高剂量率某医用电子加速器机房,周围墙体和顶板主屏蔽防护可只对X射线15 MV 600 cGy/min进行核实;副屏蔽只对X射线10 MV2200 cGy/min进行核实(应注意患者一次散射散射角的影响,可适当调整至30°);防护门屏蔽核算则对15 MV 600cGy/min治疗状态下进行防护核算;不需要对6、10、15 MV 3种治疗模式逐一核算。
Objective To discuss the main shield protection measures of the medical electron accelerator room with the high dose rate of 6, 10, 15 MV produced by the medical science. Methods According to the “Radiation Shielding Room for Radiation Therapy Part 2: Electronic Linear Accelerator Radiation Therapy Room” (GBZ / T 201.2-2011) and other methods provided for protection accounting. Results The thickness of X-ray radiation shielding masters (such as the north wall) of an MVA should be 2590 and 2624 mm, respectively; the thickness of the secondary shielding (eg, the south wall) should be 1240 and 1138 mm. At the scattering angle of 20 °, the equivalent dose rates of the secondary shielded area (1840 mm in thickness) directly connected to the main wall of the north wall with 10,15 MV X-rays by one-time scattering by patients were 4.89 and 3.05 μSv / h, respectively The protective door should be at least 110 mm thick with boron 5% polyethylene (inner) and 17 mm Pb (outer). Conclusion The main shielding of medical electron accelerator room, the surrounding wall and the roof of the medical high-dose 6,10,15 MV dose rate X-ray can be verified only by 15 MV 600 cGy / min; the secondary shielding only affects X-ray 10 MV2200 cGy / min to verify (should pay attention to the scattering angle of the first scattering of patients, may be appropriately adjusted to 30 °); protection door shielding accounting 15 MV 600cGy / min treatment under the protection of accounting; does not require 6,10, 15 MV 3 kinds of treatment mode one by one accounting.