MULTIPLE SCATTERING THEORY APPLIED TO ELECTRON DOSIMETRY

多重散射理论应用于电子剂量测定

• 批准号: 3182030
• 负责人: DAVID JETTE
• 金额: $ 11.64万
• 依托单位: INSTITUTE OF APPLIED PHYSIOLOGY/MEDICINE
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-09-02 至 1989-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3182030
• 关键词: clinical biomedical equipment; computed axial tomography; computer assisted patient care; mathematical model; neoplasm /cancer radiation therapy; particle beam; radiation therapy dosage

Electron beams are increasingly coming into use in the radiation treatment of cancer, because their rapid dose falloff minimizes irradiation of critical healthy tissues beyond the target volume. Unfortunately, for treatment planning purposes it is not yet possible to calculate the absorbed dose distribution precisely, particularly in the presence of tissue inhomogeneities and body curvature. In penetrating the body, high-energy electrons suffer a great many collisions and follow a tortuous, although mainly forward, path. It has only been recently that a number of investigators have begun to apply Fermi-Eyges multiple scattering theory to the problem of electron dosimetry, recognizing that this theory describes the behaviour of the electron beam as a reasonable first approximation, at least in a homogeneous or horizontally layered medium. It is the purpose of the proposed research to develop and apply Fermi-Eyges theory in a way which allows the accurate calculation of electron dose distributions in the presence of tissue inhomogeneities and body curvature using directly the data from computerized tomography (CT) scans. The goal is to achieve an accuracy of 5%, and preferably of 3%, in the practical calculation of electron dose in the most complicated situations likely to be encountered clinically. The method of the proposed research is to develop the Fermi-Eyges theory to a high accuracy, to simplify it mathematically into a practical computational algorithm, and to refine and verify the algorithm through experiments. The key to the theoretical work is the concept of representative electron path, and in addition it will be necessary to include in the computational algorithm a number of secondary effects which are ignored by Fermi-Eyges theory. For the experimental work, four phantoms providing progressively more complicated configurations of inhomogeneities will be use; the dose distribution throughout the phantom will be recorded on radiographic film, and thermoluminescent dosimetry (TLD) will be used to maintain the accuracy of the film dosimetry. CT scans will be used to describe the more complicated phantom configurations to the computational algorithm.

电子束在放射治疗中的应用越来越广泛。 癌症，因为它们的快速剂量衰减将辐射降至最低 关键的健康组织超过目标体积。不幸的是，对于 治疗计划的目的目前还不能计算 精确的吸收剂量分布，特别是在存在 组织不均匀和身体弯曲。在穿透身体时， 高能电子经历了多次碰撞，并经历了曲折的、 虽然主要是向前，但路径。直到最近，才有一些 研究人员已经开始将费米-艾格斯多重散射理论应用于 电子剂量学问题，认识到这一理论描述了 电子束的行为作为一个合理的一级近似，在 在均匀或水平分层的介质中最少。这就是目的 在某种程度上发展和应用费米-艾格斯理论的拟议研究 这使得能够准确地计算电子剂量分布在 组织不均匀和体曲率的存在直接使用 来自计算机断层扫描(CT)的数据。我们的目标是实现 在实际计算中，精度为5%，最好是3% 可能遇到的最复杂情况下的电子剂量 从临床上看。 提出的研究方法是将费米-艾格斯理论发展到 高精度，把它从数学上简化成一个实用的 计算算法，并通过对算法进行提炼和验证 实验。理论工作的关键是 具有代表性的电子路径，此外，还需要 在计算算法中包括许多次要效果，这些次要效果 都被费米-艾奇斯理论所忽视。对于实验工作，有四个 幻影提供了逐渐复杂的配置 将使用不均匀；整个体模的剂量分布 将记录在射线胶片上，并进行热释光剂量测定 将使用热释光(TLD)来保持胶片剂量测量的准确性。CT 扫描将用于描述更复杂的幻影配置 到计算算法。