Laser acceleration of protons for radiation therapy

描述(申请人提供)：我们提出的研究目标是使用高强度、短脉冲激光将质子加速到230 MeV的治疗能量。这一关键目标的成功完成将为开发取代质子加速标准模式的激光加速器打开大门。这可能会使质子治疗的剂量学优势以一种经济高效的方式在癌症管理中得到普遍使用。虽然理论结果表明治疗能量是可以获得的，但关键问题是在实验上向薄靶提供足够的强度，而不产生过多的预等离子体或损害靶后表面的物理完整性。这需要非常高的激光对比度，其定义为主脉冲的强度与较弱的预脉冲的强度之比，这是这些激光器的一个特征。这一提议的具体目的是1)将质子加速到治疗能量，2)进行理论模拟来指导实验过程，完善理论模型，并确认我们对基于激光的质子加速机制的理解。这将是第一次使用激光强度进行研究，预计激光强度将产生治疗能量的质子。在我们提出的方法中，我们将使用倍频来提高对比度以消除预等离子体效应，并系统地研究一系列2D参数空间来确定激光强度和靶厚度对质子能量的影响。产生的最大质子能量将使用飞行时间和分光计进行测量，并与几个不同目标的这两个变量相关联。将更详细地研究产生更大质子能量的参数空间区域。理论模拟将指导实验工作，同时根据实验结果进行改进。在过去的50年里，质子疗法已被证明与X射线疗法相比，对癌症的局部控制效果类似或更好。然而，由于它的价格是它的十倍以上，它并不是广泛可用的。这项研究将进行第一个关键步骤，以确定是否可以通过使用新的加速技术大幅降低成本。

DESCRIPTION (provided by applicant): The goal of our proposed research is to use high-intensity, short-pulse lasers to accelerate protons to a therapeutic energy of 230 MeV. The successful completion of this critical goal would open the door to the development of a laser-accelerator that would replace standard modes of proton acceleration. This would potentially allow the dosimetric advantages of proton therapy to become available in a cost-effective manner for general use in the management of cancer. While theoretical results indicate that therapeutic energies are attainable, the critical issue is to experimentally deliver a sufficient intensity to a thin target without creating an excessive preplasma or compromising the physical integrity of the rear target surface. This requires a very high laser contrast, which is defined as the ratio of the intensities of the main pulse and a weaker prepulse, which is a feature of these lasers. The specific aims of this proposal are 1) to accelerate protons to therapeutic energies, and 2) conduct theoretical simulations to guide experimental procedure, refine theoretical models, and confirm our understanding of laser-based proton acceleration mechanisms. This will be the first study using laser intensities which are predicted to yield protons of therapeutic energies. In our proposed method, we will use "frequency-doubling" to improve the contrast to eliminate preplasma effects and systematically study a series of 2D parameter spaces to determine the effect of laser intensity and target thickness on proton energy using several different targets. The maximum resulting proton energy would be measured, using time-of-flight and a spectrometer, and correlated to these two variables for several different targets. Regions of parameter space resulting in greater proton energies will be studied in greater detail. Theoretical simulations will guide experimental work, while themselves being refined based on experimental results. Over the past 50 years, proton therapy has been shown to give similar or better local control of cancer than X-ray therapy. However, because it costs more than ten times as much, it is not widely available. This research will conduct the first critical step in determining if the cost can be dramatically reduced through the use of new acceleration technology.