Accurate, easy-to-commission radiotherapy beam models

描述（由申请人提供）：蒙特卡罗是一种高度精确的放疗方法，适用于治疗头设计、机器校准和图像引导放疗等领域。例如，近年来精密放射治疗的发展要求更高的精确剂量计算，以实现充分的临床效益。蒙特卡洛可以满足这种需求。不幸的是，蒙特卡罗非常难以实现。本研究的目的是消除蒙特卡罗临床广泛应用的这一障碍。关键的要求是一个精确的，易于调试的处理梁模型。调试是确定模型参数的过程，该参数与该光束特有的测量值相匹配。使用目前的方法，一个不熟悉这种方法的临床物理学家需要几个月的时间来调试一个标准的8束加速器。这段时间长得令人无法接受。该建议是为了证明光束模型既准确又易于调试。这将实现三个具体目标：1。通过测试模拟关键加速器组件（目标和散射箔）的精度，证明蒙特卡罗在验证光束模型方面是足够精确的（1%），使用研究加速器上的测量，在提供精确能量的光束方面是独一无二的。2. 结合实验与蒙特卡罗建立详细的粒子影响图（粒子数，能量，方向），以前所未有的精度（2%）为临床光束。来自3家主要制造商的加速器的详细测量，包括源和几何变化以及光束不对称，将使用蒙特卡罗转换为影响图。根据从常规测量中提取的参数开发光束模型，每个光束在一天内完成调试。将使用影响图和剂量测量来评估准确性。实际结果将是一对电子束模型，一个用于电子，一个用于x射线，它们易于调试，满足现代放射治疗的严格精度要求，并适用于今天诊所的大部分放射治疗单元。这将使全国各地的诊所能够利用这种最先进的临床工具的计算准确性。

DESCRIPTION (provided by applicant): Monte Carlo is a highly accurate method for radiotherapy in areas as diverse as treatment head design, machine calibration, and image-guided radiotherapy. For example, recent developments in precision radiotherapy require higher accuracy dose calculation to realize full clinical benefit. Monte Carlo can meet this demand. Unfortunately, Monte Carlo is extremely difficult to implement. The objective of this study is to remove this obstacle to widespread clinical use of Monte Carlo. The key requirement is an accurate, easily commissioned model of the treatment beam. Commissioning is the process of determining the parameters of the model that match the measurements peculiar to that beam. Using current methodology, a clinical physicist unfamiliar with the method would take months to commission a standard 8-beam accelerator. This is unacceptably long. The proposal is to prove beam models may be both accurate and easy to commission. This will be accomplished with 3 Specific Aims: 1. Prove Monte Carlo is sufficiently accurate for validating beam models (1%) by testing the accuracy for simulating the key accelerator components (target and scattering foils), using measurements on a research accelerator, unique in providing beams with accurate energies. 2. Combine experiment with Monte Carlo to establish detailed maps of particle fluence (particle number, energy, direction) of unprecedented accuracy (2%) for clinical beams. Detailed measurements on accelerators from the 3 major manufacturers, including source and geometry variations and beam asymmetry, will be converted to fluence maps using Monte Carlo. 3. Develop beam models with parameters extracted from routine measurements, with commissioning done in under a day per beam. Accuracy will be evaluated using the fluence maps and dose measurements. The practical result will be a pair of beam models, one for electrons, one for x-rays, which are easy to commission, meet the stringent accuracy requirement of modern radiotherapy, and apply to the bulk of radiotherapy units in clinics today. This will allow clinics around the country to take advantage of the computational accuracy of this state-of-the-art clinical tool.