Alexander Andrew, Soisson Emilie, Renaud Marc-André, Seuntjens Jan
Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4, Canada.
Med Phys. 2012 Aug;39(8):4820-31. doi: 10.1118/1.4736423.
Despite promising research in modulated electron radiotherapy (MERT), an applicator to produce modulated electron beams and associated treatment planning software is still not commercially available. This work investigated an optimization process in treatment planning for the McGill few leaf electron collimator (FLEC) MERT delivery device. In addition, the possibility of combining MERT with photon fields was examined to investigate mixed beam radiotherapy.
A FLEC direct aperture optimization (DAO) method, in which FLEC apertures and weights were iteratively optimized was created. The authors evaluated the performance of DAO against our previous technique for generating FLEC plans and with commercially available photon beam optimization algorithms using a basic target and organ at risk geometry. The authors applied the DAO technique on a sarcoma treatment to evaluate clinical parameters. Finally, the authors examined the merit of mixing the DAO generated FLEC electron fields with photon fields to improve the dosimetry of the sarcoma treatment.
In relation to the alternative plans, the DAO generated sarcoma MERT plan was competitive in its ability to reduce the dose to OAR but weaker in its ability to highly conform the dose to the target volume. The addition of photon fields improved the quality of the MERT plan in terms of OAR sparing and target conformality.
The DAO approach yielded deliverable FLEC-based MERT plans with a limited number of fields. The approach combined with photon optimization added flexibility, where the mutual benefits of each radiation type was used in unison to improve plan quality.
尽管在调制电子放疗（MERT）方面有前景可观的研究，但用于产生调制电子束的施源器及相关治疗计划软件仍未实现商业化。本研究探讨了麦吉尔少叶电子准直器（FLEC）MERT输送装置治疗计划的优化过程。此外，还研究了将MERT与光子野相结合以探索混合束放疗的可能性。
创建了一种FLEC直接孔径优化（DAO）方法，其中FLEC孔径和权重经过反复优化。作者使用基本靶区和危及器官的几何结构，将DAO的性能与我们之前生成FLEC计划的技术以及市售光子束优化算法进行了评估。作者将DAO技术应用于肉瘤治疗以评估临床参数。最后，作者研究了将DAO生成的FLEC电子野与光子野混合以改善肉瘤治疗剂量学的优点。
与替代计划相比，DAO生成的肉瘤MERT计划在降低危及器官剂量的能力方面具有竞争力，但在使剂量高度适形于靶区体积的能力方面较弱。添加光子野在保护危及器官和靶区适形性方面提高了MERT计划的质量。
DAO方法产生了基于FLEC的可交付MERT计划，且射野数量有限。该方法与光子优化相结合增加了灵活性，两种辐射类型的优势得以共同发挥以提高计划质量。
