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目的 探讨虚拟楔形板楔形角的验证 ;楔形因子与射线能量、照射野尺寸和楔形角大小之间的关系 ;虚拟楔形野、物理楔形野和平野百分深度剂量之间的关系。方法 对西门子公司Meva tronM加速器 6MV、Primus加速器 8、18MV 3种能量X射线 ,用RFA PLUS三维水箱、RK指形电离室分别测量其 15°、30°、45°和 6 0°虚拟楔形板的楔形角和不同大小照射野的楔形因子 ;用FDM 30 0黑度计、KodakXV 2检验胶片测量 6MVX射线 30°虚拟楔形野、物理楔形野和平野的百分深度剂量 ,归一到最大剂量点并进行比较。结果 4点法测得的虚拟楔形角与设定值有良好的一致性。不论射线能量、照射野大小和楔形角大小 ,虚拟楔形板楔形因子总是约等于 1,最大偏离为 0 .0 31;对于特定能量和照射野 ,大楔形角楔形因子较小楔形角略大 ;对于特定能量和楔形角 ,大野楔形因子较小野略大 ;虚拟楔形野深度剂量曲线非常接近平野 ,两者仅有很细微的差别。结论 4点法测量虚拟楔形板楔形角可作为日常质量保证手段。虚拟楔形野较物理楔形野治疗不仅简单易行 ,更可以节省加速器出束量。虚拟楔形野与平野的深度剂量曲线的一致性简化了治疗计划或者提高了楔形野实际治疗剂量精度。
Objective To study the verification of the wedge angle of the virtual wedge plate; the relationship between the wedge factor and the ray energy, the size of the irradiation field and the size of the wedge angle; and the relationship between the virtual wedge field, the physical wedge field and the field depth percentage. Methods Three energy X-rays of MeVa tronM accelerators and Primus accelerators of 8 and 18MV from Siemens Company were measured by using a RFA PLUS three-dimensional water tank and a RK finger ionization chamber. The 15 °, 30 °, 45 ° and 60 ° virtual wedge plates Wedge angles and wedges of different size fields; the FDM 30 blackness meter, the KodakXV 2 test film measured 6 MV X-rays 30 ° virtual wedge fields, physical wedge fields and field fields Percent depth dose normalized to the maximum dose point and Compare. Results The virtual wedge angle measured by the 4-point method was in good agreement with the set value. The wedge factor of the virtual wedge is always equal to about 1 and the maximum deviation is 0.031, regardless of the energy of the radiation, the size of the radiation field and the size of the wedge angle. The wedge angle of the large wedge angle wedge is slightly larger for a specific energy and irradiation field. For a specific energy and wedge angle, the wild wedge factor slightly larger slightly larger; virtual wedge field depth dose curve is very close to the plain, only a very small difference between the two. Conclusion The 4-point method of measuring wedge angle of the virtual wedge plate can be used as a daily quality assurance means. Virtual wedge than wild wedge wild treatment is not only simple and easy, but also can save the amount of accelerator output. Consistency of the depth dose curve between the virtual wedge field and the field field simplifies the treatment plan or increases the actual therapeutic dose accuracy of the wedge field.