Schwarz Marco, Cattaneo Giovanni Mauro, Marrazzo Livia
Protontherapy Department, Trento Hospital, Via Al Desert 14, 38123 Trento, Italy; Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute of Nuclear Physics (INFN), Via Sommarive 14, 38123 Trento, Italy.
Medical Physics, San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milano, Italy.
Phys Med. 2017 Apr;36:126-139. doi: 10.1016/j.ejmp.2017.02.011. Epub 2017 Feb 24.
The application of high precision hypofractionated regimes (a.k.a. stereotactic body radiotherapy (SBRT)) to the treatment of lung cancer is a 'success story' of radiotherapy. From the technical perspective, lung SBRT is a challenging technique as all aspects of the treatment workflow, from imaging to dose calculation to treatment delivery, should be carefully handled in order to ensure consistency between planned and delivered dose. In this review such technical aspects are presented and discussed, looking at what has been developed over the years. The use of imaging techniques such as slow-CT, breath-hold CT, four-dimensional CT and mid-ventilation is reviewed, presenting the main characteristics of each approach but not necessarily to single out 'the best' solution. Concerning dose calculation, a number of studies clearly separate dose algorithms that should be considered inadequate for lung SBRT (e.g. simple pencil beam algorithms) from approaches such as convolution algorithms, Monte Carlo, and solution of the transport equation, that are much better at handling the combination of small fields and heterogenenous geometries that make dose calculation not trivial. Patient positioning and management of intrafraction motion have been two areas of significant developments, to the point where it is difficult to identify which solution represents the best compromise between technical complexity and clinical effectiveness. The review analyses several of these methods, outlining the residual uncertainties associated with each of them. Last but not least, two subjects are discussed, adaptive therapy and particle therapy, that may represent in the near future additional tools for the technical improvement of lung SBRT.
高精度大分割放疗方案（即立体定向体部放疗，SBRT）在肺癌治疗中的应用是放射治疗领域的一个“成功案例”。从技术角度来看，肺部SBRT是一项具有挑战性的技术，因为从成像到剂量计算再到治疗实施，治疗流程的各个方面都需要谨慎处理，以确保计划剂量与实际 delivered 剂量之间的一致性。在这篇综述中，将介绍并讨论这些技术方面的内容，回顾多年来的发展情况。将对慢CT、屏气CT、四维CT和中期通气等成像技术的应用进行综述，介绍每种方法的主要特点，但不一定会选出“最佳”解决方案。关于剂量计算，许多研究明确区分了一些被认为不适用于肺部SBRT的剂量算法（如简单铅笔束算法）与卷积算法、蒙特卡罗方法以及输运方程解法等，后者在处理小射野和异质几何结构组合方面表现更好，而这种组合使得剂量计算并非易事。患者定位和分次内运动管理一直是取得显著进展的两个领域，以至于很难确定哪种解决方案在技术复杂性和临床有效性之间达到了最佳平衡。该综述分析了其中几种方法，概述了每种方法存在的残余不确定性。最后但同样重要的是，讨论了自适应治疗和粒子治疗这两个主题，它们可能在不久的将来成为进一步提升肺部SBRT技术的额外工具。
