Ionoacoustics in time and frequency domain: A novel method for direct in vivo measurement of the Bragg peak position in ion beam therapy

射程验证是离子治疗中的关键问题，使其能够在临床上充分发挥其相对于光子治疗的独特优势。目前正在进行临床测试的方法依赖于核成像技术，这需要复杂而昂贵的探测器系统。此外，基于核的方法不能提供最大剂量(布拉格峰)和发射信号之间的直接关系。在我们的方法中，我们打算利用离子在组织中停止时产生的压力脉冲和相关的声波(因此是离子声学)来用超声波方法测量离子范围。这项技术提供了一种简单而直接的可能性，可以在活体和实时地将肿瘤区域的常规超声回波与最先进的铅笔束照射方案提供的单个布拉格峰的特征信号相关联。这一挑战需要在临床条件下使用较小的压力脉冲，如第一次实验测试所示。本项目的目标是实验演示微弱电离声信号的检测及其在类似临床条件下用于准确识别Bragg峰位置的应用。为此，我们将在时间上，特别是在频域上开发新的电离声探测方法，然后对质子束进行广泛的验证和改进。这一目标将通过使用强度调制能量沉积来实现，该沉积最初可以在光声装置中开发。在这个项目的第二部分，我们将在具有适当能量和束流条件的质子加速器上进行实验。最后，我们将致力于开发新的图像重建技术，旨在将Bragg峰位置与超声图像相关联，从而为未来在肿瘤治疗中部署这一独特且有前景的技术铺平道路。尽管该项目的重点是质子束，但离子声学技术也可以应用于更重的离子。

Range verification is the crucial issue in ion therapy to enable full clinical exploitation of its characteristic advantages over photon therapy. Methods currently under clinical testing rely on nuclear imaging techniques, which require complex and costly detector systems. Moreover, nuclear-based methods do not provide direct correlation between the dose maximum (Bragg peak) and the emission signal. In our approach, we intend to make use of the pressure pulse and related acoustic wave induced by ions stopping in tissue (hence ionoacoustics) to measure the ion range with ultrasound methods. This technique promises a simple and direct possibility to correlate, in vivo and in real-time, the conventional ultrasound echo of the tumor region with the characteristic signal of individual Bragg peaks delivered with the most advanced pencil-beam irradiation schemes. The challenge entails the small pressure pulse at clinical conditions, as shown in first experimental tests. The goal of this project is to demonstrate experimentally the detection of the weak ionoacoustic signal and its utilization for accurate identification of the Bragg peak position under clinical-like conditions. For this purpose, we will develop new methods of ionoacoustic detection in time and, in particular, frequency domain, and then perform extensive validation and refinement at proton beams. The goal will be achieved by using an intensity modulated energy deposition, which can be initially developed at an optoacoustic setup. In the second part of this project we will pursue experiments at proton accelerators with appropriate energies and beam conditions. Finally, we will engage in the development of new image reconstruction techniques, aiming at correlating the Bragg peak position with an ultrasound image, thus paving the way towards future deployment of this unique and promising technique in tumor therapy. Although the project is focused on proton beams, the ionoacoustic technique could also find application for heavier ions.