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

范围验证是离子治疗中至关重要的问题，它可以使临床充分利用其优于光子治疗的特点优势。目前临床试验的方法依赖于核成像技术，这需要复杂和昂贵的探测器系统。此外，基于核的方法不能提供最大剂量（布拉格峰）与发射信号之间的直接相关性。在我们的方法中，我们打算利用离子在组织中停止引起的压力脉冲和相关声波（因此是离子声学）来用超声波方法测量离子范围。这项技术保证了一种简单而直接的可能性，可以在体内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所传递的单个布拉格峰的特征信号相关联。正如第一次实验测试所示，挑战在于临床条件下的小压力脉冲。该项目的目标是通过实验证明弱离子声信号的检测及其在临床条件下准确识别布拉格峰位置的利用。为此，我们将开发新的时间和频域离子声探测方法，然后在质子束上进行广泛的验证和改进。该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设置中开发。在这个项目的第二部分，我们将在质子加速器上进行适当的能量和光束条件的实验。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，从而为这种独特而有前途的技术在肿瘤治疗中的未来部署铺平道路。虽然这个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.