医用诊断X射线半价层的测量

Measurement of half-value layer for medical diagnostic X-ray

介绍了医用诊断X射线半价层测量的原理与曲线拟合法、平均值法、内插法、作图法等四种测量方法,结合实验数据分析了平均值法、内插法和拟合法的特点。医用诊断X射线束通常为“宽束”,曲线拟合法测量半价层需考虑积累因子的影响,通过调整吸收片厚度能快速计算出半价层;平均值法对于宽束X射线在较大的吸收片厚度范围内多次测量不能减小误差;内插法测量时内插间距的选择直接影响测量结果;采用平均值法和内插法时,所选吸收片厚度应使K/K0分布在1/2两侧。

This paper introduces the principle of medical diagnostic X-ray half valence layer measurement and four kinds of measurement methods such as curve fitting,average value method,interpolation method and drawing method.Combined with the experimental data,the characteristics of average value method,interpolation method and fitting method are analyzed.The medical diagnostic X-ray beam is usually"wide beam".When measuring the half-value layer by curve fitting method,the influence of buildup factor should be taken into account,and the half-value layer can be calculated quickly by adjusting the thickness of absorption film;the average value method cannot reduce the error for multiple measurements of wide beam X-ray within a large thickness range of absorption film;the selection of interpolation distance in the measurement of interpolation method directly affects the measurement result;When the average method and interpolation method are used,the thickness of the selected absorption plate shall be such that K/K0 is distributed on both sides of 1/2.