Rykers K L, Geso M, Brown G M, Oliver L D
Department of Physical Sciences, East Melbourne Radiation Oncology Centre, Vic.
Australas Phys Eng Sci Med. 1998 Jun;21(2):73-8.
In this work a method of using Kodak X-Omat V film to measure beam profiles for dynamically wedged fields is presented. Also, the profiles determined by film measurement are compared with those measured with an ion chamber (0.12 cm3 Scanditronix RFA 300 RK) and an array of silicon diodes (11 channel Scanditronix linear diode array). The beam investigated is a 6 MV photon beam from a Varian 2100 C linear accelerator. The geometric method of positioning film and determining the central axis (CAX) position of the beam yielded results which agreed to within 1 mm with the software determined position of the CAX. The profiles measured by film agreed well with the ion chamber measured profiles in terms of overall field size, position, penumbral width, height and position of maximum and profile shape between the 20% dose levels. Film profiles deviated most from ion chamber profiles in the post-penumbra regions. Linear diode array (LDA) measured profiles matched ion chamber profiles in the post-penumbra regions, field size and general profile shape. In the region of maximum dose differences in dose of up to 4% were seen along with horizontal shifts of around 2 mm between LDA and ion chamber profiles.
在这项工作中，提出了一种使用柯达X-Omat V胶片测量动态楔形野射束轮廓的方法。此外，还将通过胶片测量确定的轮廓与使用电离室（0.12 cm³ 扫描电子管RFA 300 RK）和硅二极管阵列（11通道扫描电子管线性二极管阵列）测量的轮廓进行了比较。所研究的射束是来自瓦里安2100 C直线加速器的6 MV光子束。通过几何方法定位胶片并确定射束的中心轴（CAX）位置，其结果与软件确定的CAX位置在1 mm范围内相符。在20%剂量水平之间，胶片测量的轮廓在总野大小、位置、半值层宽度、高度以及最大值位置和轮廓形状方面与电离室测量的轮廓吻合良好。胶片轮廓在半值层后区域与电离室轮廓偏差最大。线性二极管阵列（LDA）测量的轮廓在半值层后区域、野大小和总体轮廓形状方面与电离室轮廓匹配。在最大剂量区域，LDA和电离室轮廓之间出现了高达4%的剂量差异以及约2 mm的水平偏移。
