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，以使其在临床上充分发挥其相对于光子治疗的特征优势。目前在临床测试中的方法依赖于核成像技术，这需要复杂且昂贵的探测器系统。此外，基于核的方法不提供剂量最大值（布拉格峰）和发射信号之间的直接相关性。在我们的方法中，我们打算利用压力脉冲和相关的声波所引起的离子停止在组织（因此电离声学），以测量离子的范围与超声方法。这种技术承诺一个简单和直接的可能性，在体内和实时的，传统的超声回波的肿瘤区域的特征信号的个别布拉格峰提供最先进的激光束照射计划。挑战需要在临床条件下的小压力脉冲，如第一次实验测试所示。该项目的目标是实验证明弱电离声信号的检测和其利用的布拉格峰位置的准确识别在临床条件下。为此，我们将开发新的方法，电离声检测的时间，特别是频域，然后进行广泛的验证和改进质子束。这一目标将通过使用强度调制能量沉积来实现，该能量沉积最初可以在光声装置上开发。在这个项目的第二部分，我们将在适当的能量和束流条件下在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，旨在将布拉格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。虽然该项目的重点是质子束，但电离声技术也可以应用于较重的离子。

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.