Laser acceleration of protons for radiation therapy

描述（由申请人提供）：我们拟议研究的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激光加速器的发展打开大门，激光加速器将取代质子加速的标准模式。这将潜在地允许质子治疗的剂量测定优势以具有成本效益的方式用于癌症管理的一般用途。虽然理论结果表明，治疗能量是可以达到的，关键问题是实验提供足够的强度薄的目标，而不会产生过多的preplasma或损害后靶表面的物理完整性。这需要非常高的激光对比度，其被定义为主脉冲和较弱的预脉冲的强度之比，这是这些激光器的特征。该提案的具体目标是：1）将质子加速到治疗能量，2）进行理论模拟以指导实验程序，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。 这将是第一个使用激光强度的研究，预计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，并系统地研究了一系列的二维参数空间，以确定激光强度和靶厚度对质子能量的影响，使用几个不同的目标。将使用飞行时间和光谱仪测量产生的最大质子能量，并将其与几个不同目标的这两个变量相关联。将更详细地研究导致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，质子治疗已被证明可以比X射线治疗更好地局部控制癌症。然而，由于它的成本是它的十倍以上，所以它并不广泛使用。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大降低成本。

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.