Cancer Therapy and Research Center, Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, TX 78229-4427, USA.
J Appl Clin Med Phys. 2012 Sep 6;13(5):3960. doi: 10.1120/jacmp.v13i5.3960.
A Monte Carlo model of the Novalis Tx linear accelerator equipped with high-definition multileaf collimator (HD-120 HD-MLC) was commissioned using ionization chamber measurements in water. All measurements in water were performed using a liquid filled ionization chamber. Film measurements were made using EDR2 film in solid water. Open rectangular fields defined by the jaws or the HD-MLC were used for comparison against measurements. Furthermore, inter- and intraleaf leakage calculated by the Monte Carlo model was compared against film measurements. The statistical uncertainty of the Monte Carlo calculations was less than 1% for all simulations. Results for all regular field sizes show an excellent agreement with commissioning data (percent depth-dose curves and profiles), well within 1% of difference in the relative dose and 1 mm distance to agreement. The computed leakage through HD-MLCs shows good agreement with film measurements. The Monte Carlo model developed in this study accurately represents the new Novalis Tx Varian linac with HD-MLC and can be used for reliable patient dose calculations.
利用水腔电离室进行测量，对配备了高清多叶准直器（HD-120 HD-MLC）的 Novalis Tx 医用直线加速器进行了蒙特卡罗建模。所有的水中测量均使用充满液体的电离室完成。固体水 EDR2 胶片则用于进行场射野剂量测量。利用机头或 HD-MLC 定义的开方野与测量结果进行对比。此外，还将蒙特卡罗模型计算出的叶片间和叶片漏射线与胶片测量结果进行了比较。所有模拟的蒙特卡罗计算统计不确定性均小于 1%。所有规则射野尺寸的结果均与验证数据（百分深度剂量曲线和射野轮廓）吻合良好，相对剂量差异在 1%以内，距离误差在 1mm 以内。通过 HD-MLC 的计算漏射线与胶片测量结果吻合良好。本研究中开发的蒙特卡罗模型能够准确地描述配备了 HD-MLC 的新型 Novalis Tx 医用直线加速器，并可用于可靠的患者剂量计算。
