多野照射射束蕊剂量分布的线性模型

LINEAR MODEL OF DOSE DIETRIBUTION IN INNER AREA IRRADIATING BY MULTI-FIELDS

根据高能光子射线蕊区剂量分布的特点提出了线性线束的概念。线性线束是①射束轴百分深度量为Ｐ（Ｘ）＝ａ＋ｂＸ：②正入射时同深度点百分深度量相等的线束。文中给出线件束交叉照射时重叠区剂量计算方法。并把楔形野、斜入射等统一用线性来处理，导出了单楔板多楔角计算公式等有用的公式。最后通过一实例介绍本模型使用基本方法并讨论了结果的可靠性。线性模型可用于对已有照野设计方案靶区剂量分布的分析，也可用于指导合理布野和给剂量使靶区剂量分布均匀化。

The Iinear beam model is proposed according to the characteristicsof high energy photon beams. This model of a radiation linear beam is that(1)Thepercent depth doses on the beam axis can be described by P(x)= a+ bx,(2)THE PDDsof the points which located at same depths are equal.The equations of calcuiatingdose distributiou Was Show ed for mulliple linear beams,The Wedge field andobligue beam were treated as linear, too. A example was desscribed to expldin the application of the model in detail Its result wds compared with that obtained by TPS.The linearr mo can ba used to estimate the dose distribution and also can help the doctor arra position and the dose of each field in order to make dosedistibution uniforrnly.