(NCI) Developing an Intermediate Energy Linac for Robotic Radiotherapy

 描述（由申请人提供）：使用广泛非共面射束的机器人放射治疗已被证明可有效显著改善放射治疗剂量测定，从而改善治疗结果。然而，目前通过射波刀实施该技术是低效的，并且在剂量学上不是最佳的。这严重限制了有资格接受机器人放射治疗的患者数量和接受治疗的患者可实现的临床结果。为了克服这些限制，我们建议开发一种新型的机器人放射治疗系统，可以有效地利用非共面输送空间的全部潜力来治疗大多数放射治疗患者。创新点：该系统在以下方面具有高度创新性：1）集成了光束定向和注量优化。2)显著更紧凑的直线加速器，以允许后束。3)灵活的字段大小 和MLC分辨率，以有效地治疗大多数目标尺寸。4)集成体积成像系统。本计画旨在设计一个硬件平台，以实现此机器人放射治疗系统。为了减小机架尺寸，需要显著减小直线加速器长度以及源与MLC之间的距离。我们建议设计一个新的2 MV源，以减少直线加速器的长度，并提供治疗所需的剂量率。物理MLC叶片厚度不能显著小于1 mm。为了在治疗距离上实现高MLC分辨率，射波刀在主准直器和MLC之间使用了一个垫片，增加了机架尺寸。我们建议消除间隔，但不同的焦点到肿瘤的距离（FTD），以实现所需的字段大小和MLC分辨率。这需要在巨大的解空间中进行优化，这是4p算法唯一证明的能力。体积成像是现代放射治疗不可或缺的组成部分，但不幸的是，现有的机器人系统中缺少。拟议的新直线加速器将能够从相同的2 MV直线加速器提供kV成像束，与机架或治疗床安装的成像器结合，将允许体积成像，以实现更精确的肿瘤靶向。目的：一曰：产生2 MV X射线的加速器原型设计2：设计结合成像系统3：为整个临床系统开发概念设计影响：第一阶段项目的成功将导致第一个2 MV直线加速器的设计，该加速器能够在100 cm和kV成像束处产生具有竞争力的>800 cGy/min的高剂量率，用于图像引导放射治疗。这为一种新的机器人放射治疗系统提供辐射计划铺平了技术道路，其剂量适形性超过了现有的X射线平台。更重要的是，显着增加的字段大小，吞吐量和体积成像能力将允许新的机器人系统竞争一个更大的市场，包括传统的直线加速器，比利基市场CyberKnife目前命令。

 DESCRIPTION (provided by applicant): Robotic radiotherapy using extensively non-coplanar beams has been shown effective to significantly improve radiation therapy dosimetry that leads to improved treatment outcome. However, current implementation of this technique by CyberKnife is inefficient and not optimal dosimetrically. This has severely limited both the number of patients eligible for robotic radiotherapy and the achievable clinical outcome for those who have been treated. In order to overcome these limitations, we propose to develop a novel robotic radiotherapy system that can efficiently utilize the full potential of the non-coplanar delivery space to treat the majority of radiotherapy patients. Innovation: The proposed system is highly innovative in the following aspect: 1) Integrated beam orientation and fluence optimization. 2) Significantly more compact linac to allow posterior beams. 3) Flexible field sizes and MLC resolution to efficiently treat most target sizes. 4) Integrated volumetric imaging system. This project is proposed to design a hardware platform materializing such robotic radiotherapy system. In order to reduce the gantry size, both the linac length and the distance between the source and the MLC need to be significantly reduced. We propose to design a new 2 MV source to reduce linac length and provide the required dose rate for treatment. The physical MLC leaf thickness cannot be substantially thinner than 1 mm. To achieve a high MLC resolution at the treatment distance, a spacer is used in CyberKnife between the primary collimator and the MLC, increasing the gantry dimension. We propose to eliminate the spacer but vary the focus-to-tumor distances (FTD) to achieve desired field size and MLC resolution. This requires optimization in an enormous solution space, a capacity uniquely demonstrated by the 4p algorithm. Volumetric imaging has been an indispensable component of modern radiotherapy but unfortunately missing from existing robotic systems. The proposed new linac will be able to deliver kV imaging beams from the same 2 MV linac, which in combination with gantry or couch mounted imagers will allow volumetric imaging for more precise tumor targeting. Aims: 1: Prototypical design of the accelerator to produce 2 MV X-rays 2: Design incorporated imaging system 3: Develop a conceptual design for the entire clinical system Impact: Success of the Phase I project would lead to the design of the first 2 MV linear accelerator capable of producing a competitively high dose rate of >800 cGy/min at 100 cm and kV imaging beams for image guided radiotherapy. This paves the technical path to a new robotic radiotherapy system delivering radiation plans with dose conformality surpassing existing X-ray platforms. More importantly, the significantly increased field size, throughput and the volumetric imaging capacity would allow the new robotic system to compete for a much larger market, including that for conventional linacs, than the niche market CyberKnife currently commands.