目的:这项研究的目的是确定PTWBeamscan程序在利用多个检测器从平坦滤波自由光束轮廓确定拐点时的准确性。
方法:具有6FFF和10FFF光子能量和10厘米的真光束线性加速器,15cm和20cm场尺寸用于该研究。使用PTW的729、1,500和1,600以及Starcheck系统进行了轮廓测量,带有Beamscan系统的Pinpoint3D,和直线加速器的好象.在Excel电子表格和Beamscan软件中都使用一阶导数来分析原始测量数据以定位拐点,并计算FWHM。研究了Excel表格计算与软件程序之间的拐点和FWHM的准确性。
结果:对于729阵列中的10X10cm2,X6FFF和X10FFF能量的最大FWHM差异为5.16mm和5.04mm,分别。对于具有15×15cm2场大小的1,600个SRS阵列,最大差异为2.26mm。10X10cm2和20X20cm2场尺寸的手动和软件分析之间的FWHM差异在729,1,500,1,600SRS,Starcheck,精确定位3D,和PID。相比之下,在15×15cm2场尺寸的场宽度差异中没有检测到上升或下降模式。同样,除了1600个SRS阵列之外的所有探测器,一阶导数的峰值出现在15X15cm2场大小的腔室位置。
结论:测量的分辨率越高,拐点和FWHM的准确性越高。无论测量分辨率如何,波束扫描软件提供的FWHM更接近各自的标称场大小。在所有探测器中,使用ExcelStarcheck和EPID获得的结果与软件分析获得的值吻合良好。因此,结果表明,Beamscan软件在确定FFF光束轮廓的拐点方面是如此准确,并用于常规轮廓分析。
OBJECTIVE: The goal of this study is to determine the accuracy of the PTW Beamscan program in determining the inflection point from Flattening Filter Free Beam Profile utilizing Multiple Detectors.
METHODS: True Beam Linear Accelerator with 6FFF and 10FFF Photon Energies and 10 cm, 15 cm and 20 cm Field Sizes were used for this study. Profile measurements were taken with PTW\'s 729, 1,500, and 1,600 and the Starcheck system, the Pinpoint 3D with Beamscan system, and Linac\'s EPID. The first-order derivative was utilized in both the Excel spreadsheet and Beamscan software to analyse raw measured data to locate inflection point and the FWHM was calculated. The accuracy of inflection points and FWHM between the Excel sheet calculation and the software program were investigated.
RESULTS: For 10X10 cm2 in the 729 Array, the greatest differences in FWHM were 5.16 mm and 5.04 mm for the X6 FFF and X10 FFF Energies, respectively. The largest difference was 2.26 mm for 1,600 SRS arrays with a 15×15 cm2 field size. The difference in FWHM between Manual and software analysis for 10X10 cm2 and 20X20 cm2 Field Sizes is in decreasing order for detectors from 729, 1,500, 1,600 SRS, Starcheck, Pinpoint 3D, and EPID. In contrast, there is no climbing or declining pattern detected in the difference in Field Width for the 15×15 cm2 Field Size. Similarly, for all detectors except the 1,600 SRS array, the peak of the first-order derivative occurs at the chamber position for a 15X15 cm2 field size.
CONCLUSIONS: The higher resolution of measurement yields more accuracy in inflection point and the FWHM. Irrespective of measurement resolution, the Beamscan software provided the FWHM closer to the respective nominal Field Size. Out of all detectors, results obtained with Excel Starcheck and EPID are good in agreement with values obtained by the software analysis. Thus, it is shown that Beamscan software is so accurate in determining inflection point of a FFF beam profile and used for routine profile analysis.