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Purpose: To grasp the radiation dose level from installation of γ-knife and its protective performance before it was used in medicine, and to improve the radiation monitoring system and quality control project with installation and application of γ-knife.Materials and methods: A head γ-knife typed OUR was used as the study object, other test tools such as SG-102 environmental X-γ dosimeter,451P radiation survey dosimeter, PTW UNIDOS dosimeter, chamber(0.125cm3 and 0.015cm3), φ 160cm PMMA spherical phantom and films(MD-55 and Kodak EDR2) were adopted.Results: (1) The dose rate measured from operation position, observation window were 45 μ Gy/h and 200 μ Gy/h respectively, while each 60Co medical source was being delivered from lead shielding container to the shielding body ofγ-knife, and the effective doses received from operators were (5.0-16) μ Sv in the course of sources installing(integral of 30min).(2) It is shown that the dose rate measured from the shielding surface of γ-knife, middle line of the surface of γ-knife therapy bodys shielding door, the location up and down of the the doors middle line were (0.35-21) μ Gy/h, 140 μ Gy/h, 79.7 μ Gy/h and 75.4 μ Gy/h respectively when the γ-knife was in the state of non-therapy.Simultaneously, the highest dose rate of the position 100cm away from the shielding body was 4.0 μ Gy/h in the same non-irradiation state.(3) The dose rate near thetreatment room wall facing the fnrst scatter field was (550-2570) μ Gy/h and the dose value outside this wall was (0.6-3.5) μ Gy/h in the radiotherapy with φ 18mm collimator, while the dose rate from the second scatter field were (5-30) μ Gy/h near the wall inside and (0.10-0.30) μ Gy/h near the wall outside in this treatment state.In addition, the radiation dose rate measured near the treatment room door were 12 μ Gy/h(inside) and 0.89 μ Gy/h (outside).(4) It is illustrated that the error between mechanical center and radiation field center of the γ-knife was 0.28mm, the focus dose rate was 351cGy/min(φ 18mm), the disparity between the projected dose and therapeutic dose was-1.0% and the ratio of focus radiation dose with "0"collimator versus "φ 18mm"collimator was 0.1%.Otherwise, relative helmet index(K) and penumbra of collimator(P) were measured, and they were described as follows: K(φ 18/ φ8)=1.000,K(φ14/φ18)=0.980,K(φ8/φ18)=0.897 and K(φ4/φ18) =0.570 while Pφ4, Pφ8, Pφ14 and Pφ18 were (2.0-3.2) mm, (2.8-5.2) mm, (3.1-7.3) mm and (3.7-8.9) mm respectively.(5) Basic safety and interlock were set to meet the clinic requirement and to avoid accidental irradiation.Conclusions: Firstly, The basic protective performance and safety should meet the relative requirements of γ-knife technical standard before.it was used in clinic.Secondly, all the performance should be tested in the normal application so as to assure the radiation safety and credible radiotherapy with the γ knife.