In this study, the beam characteristics of a Euromechanics add-on MLC that has been installed on a Varian CLINAC 2100 C/D linear accelerator are presented. This was the first installation of 60-leaf PMLC from Euromechanics Company worldwide and all mechanical and dosimetric parameters were measured before clinical use of this kind of MLC. Mechanical tests were executed for different gantry and collimator angles. Leaf position accuracy and leaf gap reproducibility were checked with four different tests. The leaf transmissions, collimator (Sc), phantom (Sp), total (Sc,p) scatter factors, output of the machine, beam profiles for off-axis ratios, central axis depth dose, flatness, symmetry and penumbra have been measured for different field sizes pre and post MLC installation in 6 and 18 MV-mode. To evaluate the effect of new data on clinical plans, different beam setup configurations conformed with MLC and custom blocks were planned on CT images of thorax a CIRS phantom model 002LFC in the same treatment planning system. Leaf position in picket fence test found to be in range between 4.89–5.02 cm instead of nominal 5 cm, however the results of this test with EPIDs image and PIPSpro software showed the higher deviation rather than the results reported from the tests with EBT3 films. The measured data showed that on average Sc,p and Sc were increased 0.22% (P=0.86) and 0.34% (P=0.86) for 6 MV and 0.37% (P=0.84) and 0.42% (P=0.88) for 18 MV beams for different field sizes, respectively. Good agreement was observed between the PDD and profile curves pre and post MLC installation that was expected based on no changes in beam energy and geometry of the collimators. Based on the mechanical and dosimetry results which have been achieved from our different standard tests, it was found no significant differences between pre and post MLC installation values. This indicates, installation and using this system is clinically acceptable.

在这项研究中，介绍了安装在瓦里安 CLINAC 2100 C/D 直线加速器上的 Euromechanics 附加 MLC 的光束特性。这是欧洲机械公司在全球范围内首次安装的 60 叶 PMLC，并且在这种 MLC 临床使用之前测量了所有机械和剂量学参数。对不同的机架和准直器角度进行了机械测试。叶位置准确性和叶间隙可重复性通过四种不同的测试进行检查。叶片透射率、准直器 (Sc)、体模 (Sp)、总 (Sc,p) 散射因子、机器的输出、离轴比的光束轮廓、中心轴深度剂量、平坦度、对称性和半影已被测量为在 6 和 18 MV 模式下安装 MLC 前后不同的场尺寸。为了评估新数据对临床计划的影响，符合 MLC 的不同光束设置配置和定制块是在同一治疗计划系统中对胸部 CT 图像进行规划的 CIRS 体模模型 002LFC。发现栅栏测试中的叶子位置在 4.89-5.02 厘米之间，而不是名义上的 5 厘米，但是使用 EPID 图像和 PIPSpro 软件的测试结果显示出更高的偏差，而不是使用 EBT3 薄膜的测试报告的结果。测量数据显示，6 MV 的 Sc,p 和 Sc 平均增加 0.22% (P=0.86) 和 0.34% (P=0.86)，18 MV 增加 0.37% (P=0.84) 和 0.42% (P=0.88)分别用于不同场大小的 MV 波束。在 PDD 和 MLC 安装前后的剖面曲线之间观察到良好的一致性，这是基于准直器的光束能量和几何形状没有变化而预期的。根据我们不同标准测试获得的机械和剂量测定结果，发现 MLC 安装前和安装后值之间没有显着差异。这表明，安装和使用该系统在临床上是可以接受的。