Innovations and the Use of Collimators in the Delivery of Pencil Beam Scanning Proton Therapy.
Innovations and the Use of Collimators in the Delivery of Pencil Beam Scanning Proton Therapy.
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DOI：
10.14338/ijpt-20-00039.1
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发表时间：
2021
影响因子：
1.7
通讯作者：
Smith BR
中科院分区：
文献类型：
--
作者：
Hyer DE;Bennett LC;Geoghegan TJ;Bues M;Smith BR
准直技术的发展已成为笔形束扫描（PBS）质子治疗中最近的焦点，通过特定场或特定能量层的准直来改善靶区的一致性和健康组织的保护。鉴于低能量治疗的准直器越来越受欢迎，这项工作的目的是总结最近的文献，集中在PBS的准直器的疗效，并强调临床和临床前准直器的发展。在这项工作中提出的准直器分为3类：每场孔径，多叶准直器（MLC），和滑杆准直器。对于每种情况下，系统设计和规划方法进行了总结和相互比较，从现有的文献。能量特定准直仍然是PBS中的一个新范例，并介绍了针对PBS定制的2种特定准直器，包括动态准直系统（DCS）和Mevion自适应孔径。PBS期间的准直可以改善目标一致性以及相关的健康组织和关键结构避免。在能量特定准直器和静态孔径之间，静态孔径由于仅准直射束的眼睛视图中的目标的最大投影而具有最差的剂量一致性，但仍然提供了对未准直治疗的改进。虽然外部准直器增加了次级中子的产生，但准直初级束的好处似乎超过了风险。最大的好处是低能量治疗部位。当前文献的共识支持在某些条件下在PBS中使用外部准直器，即低能量治疗或标称光斑尺寸较大的情况。虽然最近的许多研究描绘了一幅支持性的画面，但了解PBS中准直的局限性也很重要，这些局限性特定于每种准直器类型。能量特定准直的出现和范例为PBS质子治疗带来了许多希望。
The development of collimating technologies has become a recent focus in pencil beam scanning (PBS) proton therapy to improve the target conformity and healthy tissue sparing through field-specific or energy-layer–specific collimation. Given the growing popularity of collimators for low-energy treatments, the purpose of this work was to summarize the recent literature that has focused on the efficacy of collimators for PBS and highlight the development of clinical and preclinical collimators. The collimators presented in this work were organized into 3 categories: per-field apertures, multileaf collimators (MLCs), and sliding-bar collimators. For each case, the system design and planning methodologies are summarized and intercompared from their existing literature. Energy-specific collimation is still a new paradigm in PBS and the 2 specific collimators tailored toward PBS are presented including the dynamic collimation system (DCS) and the Mevion Adaptive Aperture. Collimation during PBS can improve the target conformity and associated healthy tissue and critical structure avoidance. Between energy-specific collimators and static apertures, static apertures have the poorest dose conformity owing to collimating only the largest projection of a target in the beam's eye view but still provide an improvement over uncollimated treatments. While an external collimator increases secondary neutron production, the benefit of collimating the primary beam appears to outweigh the risk. The greatest benefit has been observed for low- energy treatment sites. The consensus from current literature supports the use of external collimators in PBS under certain conditions, namely low-energy treatments or where the nominal spot size is large. While many recent studies paint a supportive picture, it is also important to understand the limitations of collimation in PBS that are specific to each collimator type. The emergence and paradigm of energy-specific collimation holds many promises for PBS proton therapy.