Accurate, easy-to-commission radiotherapy beam models

描述(由申请人提供)：蒙特卡罗是一种用于治疗头部设计、机器校准和图像引导放射治疗等领域的高精度放射治疗方法。例如，精密放射治疗的最新发展要求更准确的剂量计算，以实现充分的临床效益。蒙特卡洛可以满足这一需求。不幸的是，蒙特卡洛的实现极其困难。这项研究的目的是消除蒙特卡罗广泛临床应用的这一障碍。关键的要求是要有一个准确的、易于调试的处理梁模型。调试是确定与该光束特有的测量结果相匹配的模型参数的过程。按照目前的方法，一位不熟悉这种方法的临床物理学家需要几个月的时间才能投入使用一台标准的8束加速器。这太长了，令人无法接受。这项提议是为了证明波束模型可能既准确又易于调试。这将通过3个具体目标来完成：1.通过使用研究加速器上的测量来测试模拟关键加速器组件(目标和散射箔)的准确性，证明蒙特卡罗足够准确地验证束流模型(1%)，该加速器在为束流提供准确能量方面是独一无二的。2.将实验与蒙特卡罗相结合，建立临床束流粒子通量(粒子数、能量、方向)的详细地图，具有前所未有的精度(2%)。来自三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束流不对称，将使用蒙特卡罗转换为通量图。3.使用从常规测量中提取的参数开发梁模型，每根梁的调试时间不到一天。准确度将使用通量图和剂量测量进行评估。实际结果将是一对束流模型，一个用于电子，一个用于X射线，易于调试，满足现代放射治疗的严格精度要求，并适用于当今临床上的大部分放射治疗单位。这将使全国各地的诊所能够利用这一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.