Division of Medical Physics and Biophysics, Department of Radiation Oncology, Dana-Farber Cancer Institute/ Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
J Appl Clin Med Phys. 2010 Jan 28;11(1):3057. doi: 10.1120/jacmp.v11i1.3057.
One of the applications of MatriXX (IBA Dosimetry) is experimental verification of dose for IMRT, VMAT, and tomotherapy. For cumulative plan verification, dose is delivered for all the treatment gantry angles to a stationary detector. Experimental calibration of MatriXX detector recommended by the manufacturer involves only AP calibration fields and does not address angular dependency of MatriXX. Angular dependency may introduce dose bias in cumulative plan verification if not corrected. For this reason, we characterized angular dependency of MatriXX and developed a method for its calibration. We found relatively large discrepancies in responses to posterior vs. anterior fields for four MatriXX (Evolution series) detectors (up to 11%), and relatively large variability of responses as a function of gantry angle in the gantry angle ranges of 91 degrees-110 degrees and 269 degrees-260 degrees. With our calibration method, the bias due to angular dependency is effectively removed in experimental verification of IMRT and VMAT plans.
MatriXX（IBA 剂量学）的应用之一是对调强放疗（IMRT）、容积旋转调强放疗（VMAT）和螺旋断层放疗（tomotherapy）的剂量进行实验验证。对于累积计划验证，需要将所有治疗机架角度的剂量输送到一个固定的探测器上。制造商推荐的 MatriXX 探测器的实验校准仅涉及 AP 校准场，并未解决 MatriXX 的角度依赖性。如果不进行校正，角度依赖性可能会导致累积计划验证中的剂量偏差。出于这个原因，我们对 MatriXX 的角度依赖性进行了特征描述，并开发了一种对其进行校准的方法。我们发现四个 MatriXX（Evolution 系列）探测器的后向与前向场的响应存在较大差异（高达 11%），并且在机架角度范围为 91 度-110 度和 269 度-260 度时，响应随机架角度的变化也较大。通过我们的校准方法，可以有效地消除在 IMRT 和 VMAT 计划的实验验证中由于角度依赖性引起的偏差。
