Kliauga P, Amols H, Lindborg L
Radiat Res. 1986 Feb;105(2):129-37.
The relationship between dose mean lineal energy and relative variance has been exploited previously to derive yD from the calculated variance in current measurements in steady and uniform radiation fields. Recently Kellerer and Rossi made the observation that utilization of two detectors can make the variance technique practicable in time-varying fields. We report here the first measurements of yD for 10 MeV X rays and 9 and 18 MeV electrons from a pulsed linear accelerator using the variance method. Two independent analog-to-digital converters were used to obtain data from two spherical proportional counters in synchrony with the beam pulse. The method is described in detail and results are reported for site diameters of 1/2, 1, and 2 microns. Data for an accurate determination of yD can be obtained with this technique in less than 1 min, making possible an essentially "on line" determination of yD or zD in a clinical situation.
剂量平均线能量与相对方差之间的关系先前已被用于从稳态和均匀辐射场中当前测量的计算方差推导yD。最近，凯勒勒和罗西观察到，使用两个探测器可使方差技术在时变场中切实可行。我们在此报告使用方差法对来自脉冲直线加速器的10 MeV X射线以及9 MeV和18 MeV电子的yD进行的首次测量。使用两个独立的模数转换器，与束脉冲同步从两个球形正比计数器获取数据。详细描述了该方法，并报告了1/2、1和2微米位点直径的结果。使用该技术可在不到1分钟的时间内获得用于准确测定yD的数据，从而有可能在临床情况下对yD或zD进行基本“在线”测定。
