Radiotherapy Centre West, PO Box 432, NL-2501 CK, The Hague, The Netherlands.
Phys Med Biol. 2010 Aug 21;55(16):4601-14. doi: 10.1088/0031-9155/55/16/S13. Epub 2010 Jul 29.
This study presents data for verification of the iPlan RT Monte Carlo (MC) dose algorithm (BrainLAB, Feldkirchen, Germany). MC calculations were compared with pencil beam (PB) calculations and verification measurements in phantoms with lung-equivalent material, air cavities or bone-equivalent material to mimic head and neck and thorax and in an Alderson anthropomorphic phantom. Dosimetric accuracy of MC for the micro-multileaf collimator (MLC) simulation was tested in a homogeneous phantom. All measurements were performed using an ionization chamber and Kodak EDR2 films with Novalis 6 MV photon beams. Dose distributions measured with film and calculated with MC in the homogeneous phantom are in excellent agreement for oval, C and squiggle-shaped fields and for a clinical IMRT plan. For a field with completely closed MLC, MC is much closer to the experimental result than the PB calculations. For fields larger than the dimensions of the inhomogeneities the MC calculations show excellent agreement (within 3%/1 mm) with the experimental data. MC calculations in the anthropomorphic phantom show good agreement with measurements for conformal beam plans and reasonable agreement for dynamic conformal arc and IMRT plans. For 6 head and neck and 15 lung patients a comparison of the MC plan with the PB plan was performed. Our results demonstrate that MC is able to accurately predict the dose in the presence of inhomogeneities typical for head and neck and thorax regions with reasonable calculation times (5-20 min). Lateral electron transport was well reproduced in MC calculations. We are planning to implement MC calculations for head and neck and lung cancer patients.
本研究提供了数据，用于验证 iPlan RT 蒙特卡罗（MC）剂量算法（德国 Feldkirchen 的 BrainLAB）。MC 计算结果与铅笔束（PB）计算结果和模体中的验证测量结果进行了比较，这些模体使用肺等效材料、空气空腔或骨等效材料模拟头颈部和胸部，以及在 Alderson 人体模型中进行。在均匀模体中测试了 MC 对微多叶准直器（MLC）模拟的剂量准确性。所有测量均使用电离室和带有 Novalis 6 MV 光子束的柯达 EDR2 胶片进行。在均匀模体中，用胶片测量和 MC 计算得到的剂量分布在椭圆形、C 形和曲折形射野以及临床调强放疗（IMRT）计划中非常吻合。对于完全封闭 MLC 的射野，MC 比 PB 计算更接近实验结果。对于大于不均匀性尺寸的射野，MC 计算与实验数据吻合良好（在 3%/1mm 以内）。在人体模型中的 MC 计算与适形射野计划的测量结果吻合良好，与动态适形弧和 IMRT 计划的吻合也合理。对 6 例头颈部和 15 例肺癌患者进行了 MC 计划与 PB 计划的比较。我们的结果表明，MC 能够在具有典型头颈部和胸部不均匀性的情况下准确预测剂量，计算时间合理（5-20 分钟）。MC 计算中很好地再现了侧向电子输运。我们计划对头颈部和肺癌患者实施 MC 计算。
