Combined radiation acoustics and ultrasound imaging for real-time guidance in radiotherapy

放射治疗可以是许多类型癌症的高效治疗。实现这一目标的一个主要障碍是 完全治愈的希望是当前的递送过程，其中通常暴露最初计划的肿瘤区域 电离辐射随时间的固定模式，而与目标变形、器官运动或功能无关。到 为了避免遗漏，通过增加规划来处理该前馈过程中的几何不确定性， 肿瘤周围的边缘，但必然导致不必要的暴露未涉及的组织，这可能导致 致人衰弱的毒性我们假设正常组织受到的有害辐射剂量可能会显著增加， 通过使用反馈系统来减少，该反馈系统将“知道”肿瘤的形状和位置以及肿瘤的位置。 和输送过程中辐射剂量的强度。这一框架需要具备独特的能力， 在辐射递送期间，同时对吸收剂量和靶向肿瘤解剖结构进行成像，这不是 这在现有技术下是可能的。 辐射物理学中的一种已知现象是由于辐射的热膨胀而产生声波。 吸收穿透性辐射后的物质。检测该辐射诱导的声信号 从临床治疗光束中分离的方法最近已经被证明，但还没有在临床上实现。该信号 作为治疗光束的结果在真实的时间中“免费”存在。信号可以用 超声检测器检测并处理以揭示沉积能量/剂量的位置和强度。 此外，超声技术也早已被建立用于医学成像和监测。 肿瘤大小、形状和位置，而不引入电离辐射。 因此，我们建议将辐射声学和超声成像的联合收割机测量结合起来， 集成系统，采用先进的矩阵阵列探头，实时确定输送的体积 根据当天的肿瘤形状和位置调整放射剂量，并最终优化肿瘤靶向， 在线反馈。该系统将在体模和临床前模型中进行优化。其次，它的可行性和 多功能性将用于治疗肝脏和胰腺肿瘤，这两个侵袭性癌症部位， 由于变形和生理运动引起的剂量错位不仅损害肿瘤根除， 影响患者的重要功能和后续治疗结果。 影响声明：我们的目标是实施新的，安全的，简单的，具有成本效益的技术和方法， 引导放射治疗输送，可提供同时的肿瘤跟踪和剂量补偿 能力的这些技术将在肝癌和胰腺癌的试点临床研究中进行评估， 证明翻译的可行性和潜力。如果成功，这种反馈技术将有一个 对个性化放射治疗和实现最佳治疗结果产生重大影响。

Radiotherapy can be a highly effective treatment for many types of cancers. A major impediment to achieving its full curative promise is the current delivery process, where typically the originally planned tumor area is exposed to a fixed pattern of ionizing radiation over time irrespective of target deformations, organ motion, or function. To avoid misses, geometric uncertainties in this feedforward process are dealt with by increasing the planning margin around the tumor, but of necessity result in unnecessary exposure of uninvolved tissue which can lead to debilitating toxicities. We hypothesize that the unwanted radiation dose to normal tissues could be significantly reduced by using a feedback system that would “know” the shape and location of the tumor as well as the location and intensity of the irradiated dose during delivery. This framework would require the unique ability to simultaneously image the absorbed dose and the targeted tumor anatomy during radiation delivery, which is not possible with currently existing technologies. A known phenomenon in radiation physics is the generation of acoustic waves due to thermal expansion of a substance following the absorption of penetrating radiation. Detection of this radiation induced acoustic signal from clinical treatment beams has been recently demonstrated but has not been clinically realized. That signal exists “for free” in real time as a consequence of the treatment beam. The signal can be measured with ultrasound detectors and processed to reveal the location and intensity of the deposited energy/dose. Furthermore, ultrasound technologies have also long been established for medical imaging and monitoring of tumor size, shape and location, without introducing ionizing radiation. Therefore, we propose to combine measurements of radiation acoustics and ultrasound imaging in an integrated system using advanced matrix array probes to determine in real-time the volumetric delivered radiation dose with respect to that day’s tumor shape and location, and ultimately to optimize tumor targeting via online feedback. The system will be optimized in phantoms and preclinical models. Then, its feasibility and versatility will be tested for treatment of tumors in the liver and the pancreas, two aggressive cancer sites where misplaced dose due to deformation and physiological motion not only compromises tumor eradication but also affects vital functions in the patient and subsequent treatment outcomes. Impact statement: We aim to implement new, safe, simple, cost effective technology and methods for online guidance of radiotherapy delivery that can provide simultaneous tumor tracking and dose compensation capabilities. These technologies will be evaluated in a pilot clinical study of liver and pancreatic cancers to demonstrate feasibility and potentials for translation. If successful, this feedback technology will have a significant impact on personalizing radiotherapy delivery and achieving optimal treatment outcomes.