^(60)Co放射治疗共面相邻野预留间隔设计的实验研究

Experimental study on planning prepared separation of adjacent fields in 60 Co radiotherapy

目的 :验证几何计算法设计60 Co相邻野预留间隔的准确性 ,探讨更精确的设计方法。方法 :通过模拟测量绘制线束扩展函数曲线 ,与几何计算法计算结果对照比较 ;利用线束扩展函数曲线 ,计算不同射野宽度相邻野组合预留间隔计算值与测量值偏差。结果 :①两种方法得出的线束扩展函数曲线有明显差异。②两小野组合计算值低于测量值 ,两大野组合计算值高于测量值 ,大野与小野或两个中等野组合计算值与测量值偏差较小。结论 :几何计算法设计60 Co相邻野预留间隔有偏差 。

Objective:To check the accuracy of prepared separation obtained by geometric calculation method and to explore the more accurate method. Methods: The different bean spread function curves drawn by simulated measurement compare with the results of geometric calculation method.Through the curves, the deviations of calculated separation and measured separation of different adjacent fields were obtained.Results:①The beam spread function curves drawn by two kinds of methods have marked differences.②The calculation value was less than measured value in two small size fields;The calculation value was more than measured value in two large size fields;The calculated value was equal to measured value in one large size and one small size fields or two middle fields.Conclusions:There is deviation in planning prepared separation of adjacent fields in 60 Co therapy by geometric calculation method,so,the penumbra overlapping method is more accurate.