Nuclear Metrology, Ecole Polytechnique, Université Libre de Bruxelles, Bruxelles, Belgium; Radiothérapy Department, Institut Jules Bordet, Bruxelles, Belgium.
Nuclear Metrology, Ecole Polytechnique, Université Libre de Bruxelles, Bruxelles, Belgium; Radiothérapy Department, Institut Jules Bordet, Bruxelles, Belgium.
Phys Med. 2019 Jan;57:207-214. doi: 10.1016/j.ejmp.2018.12.037. Epub 2019 Jan 15.
This paper studies the feasibility of using Monte Carlo (MC) for treatment planning of intraoperative electron radiation therapy (IOERT) procedure to get 3D dose by using patient's CT images.
The IOERT treatment planning was performed using the following successive steps: I) The Mobetron 1000® machine was modelled with the EGSnrc MC codes. II) The MC model was validated with measurements of percentage depth doses and profiles for three energies (12, 9, 6) MeV. III) CT images were imported as DICOM files. IV) Contouring of the planning target volume (PTV) and the organs at risk was done by the radiation oncologist. V) The medical physicist with the radiation oncologist, had chosen the same parameters of IOERT procedures like energy, applicator (type, size) and using or not bolus. VI) Finally, dose calculation and analysis of 3D maps was carried out.
The tuning process of the MC model provides good results, as the maximum value of the root mean square deviation (RMSD) was less than 3% between the MC simulated PDDs and the measured PDDs. The contouring and dose analysis review were easy to conduct for the classical treatment planning system. The radiation oncologist had many tools for dose analysis such as DVH and color wash for all the slides. Summation of the 3D dose of IOERT with other radiotherapy plans is possible and helpful for total dose estimation. Archiving and documentation is as good as treatment planning system (TPS).
The method displayed in this paper provides a step forward for IOERT Dosimetry and allows to obtain accurate dosimetry of treated volumes.
本研究旨在利用蒙特卡罗（MC）模拟方法，通过患者 CT 图像获取术中电子放射治疗（IOERT）计划的三维剂量分布，从而评估其可行性。
IOERT 治疗计划采用以下步骤进行：I）使用 EGSnrc MC 代码对 Mobetron 1000® 机器进行建模。II）通过对三种能量（12、9、6 MeV）的百分深度剂量和剂量分布进行测量，对 MC 模型进行验证。III）将 CT 图像以 DICOM 文件的形式导入。IV）由放射肿瘤学家对计划靶区（PTV）和危及器官进行轮廓勾画。V）医学物理师与放射肿瘤学家共同选择 IOERT 程序的相同参数，如能量、施源器（类型、大小）以及是否使用填充物。VI）最后，进行剂量计算和三维图谱分析。
MC 模型的调整过程提供了良好的结果，因为 MC 模拟的 PDD 与实测 PDD 之间的最大均方根偏差（RMSD）值小于 3%。经典治疗计划系统的轮廓勾画和剂量分析复查易于进行。放射肿瘤学家有许多剂量分析工具，如所有切片的剂量体积直方图（DVH）和彩色冲洗图。IOERT 的三维剂量与其他放射治疗计划的叠加有助于总剂量的估计。存档和文档记录与治疗计划系统（TPS）一样完善。
本文所述方法为 IOERT 剂量学提供了新的思路，可获得准确的治疗体积剂量分布。
