The purpose of this study is to introduce and demonstrate a novel graphical method to determine effective bremsstrahlung focal spot size and shape of the therapeutic beam from a linear accelerator. The energy distribution within the beam spot allows in determining effective bremsstrahlung size and shape of beam spot. The transverse and radial dose profiles were measured for a range of field sizes in an isocentric setup. The Length of direct focal region (LDFR) on either side of profiles were determined through the de-convolution of dose profile. The graph plotted for LDFR versus field size helps in determining properties of beam spot. The dimensions of FWHM of effective bremsstrahlung focal spot were found elliptical in nature close to the order of 1 mm. This method allows determination of FWHM of the effective bremsstrahlung focal spot that fairly falls within the range of dimension of FWHM of beamspot published in literature.

本研究的目的是介绍和展示一种新的图形方法，用于确定有效轫致辐射焦斑大小和治疗光束的形状。直线加速器。束斑内的能量分布允许确定束斑的有效韧致辐射尺寸和形状。横向和径向剂量分布是在等中心设置中测量的一系列场大小。通过剂量分布的去卷积确定分布两侧的直接焦点区域 (LDFR) 的长度。LDFR 与场大小的关系图有助于确定束斑的特性。发现有效轫致辐射焦斑的 FWHM 的尺寸本质上是椭圆形的，接近 1 mm 的数量级。该方法允许确定有效轫致辐射焦斑的 FWHM，该焦斑完全落在文献中公布的束斑 FWHM 尺寸范围内。