ELECTRON DOSE CALCULATION USING THE BIPARTITION

电子束现在广泛用于放射治疗， 癌症，因为它们的快速剂量下降最大限度地减少了辐射的关键 治疗体积以外的健康组织。不幸的是为了治疗 规划目的，目前还不可能定期计算 准确的吸收剂量分布，特别是在存在 局部组织的不均匀性，例如气腔、骨和肺。 拟议研究的总体目标是开发电子剂量- 对于大多数情况来说足够精确的计算算法 预期临床上会遇到复杂的情况，但 实用的意义上说，能够在计算机化的 治疗计划系统（计算时间足够短）。的目标 该项目是在这些计算机算法中实现5%的准确度， 或优选3%。 电子输运的双分配模型已经被开发出来， 这一模式将通过纳入最近的多个- 描述前向束电子的散射理论。这 将通过使用物理学的基本定律来实现， 结合所得公式的数学简化， 以在保持精度的同时获得短的计算时间。的 随着综合模型的发展，其准确性将不断得到检验 通过EGS 4蒙特卡罗计算，以及后来的项目， 医用电子线阵剂量分布实验 加速器

Electron beams are now in widespread use in the radiation treatment of cancer because their rapid dose falloff minimizes irradiation of critical healthy tissues beyond the treatment volume. Unfortunately, for treatment planning purposes it is not yet possible to routinely calculate the absorbed dose distribution accurately, particularly in the presence of localized tissue inhomogeneities such as air cavities, bone, and lung. The overall goal of the proposed research is to develop electron dose- calculation algorithms which are sufficiently accurate for the most complicated situations expected to be encountered clinically, yet practical in the sense of being able to be implemented in a computerized treatment planning system (short enough calculation time). The goal of the project is to achieve in these computer algorithms an accuracy of 5%, or preferably 3%, throughout the treatment volume. A Bipartition Model for electron transport has already been developed, and this model will be extended through incorporation of recent multiple- scattering theories describing the forward-directed beam electrons. This will be accomplished through use of the basic laws of physics in conjunction with mathematical simplification of the resulting formulas, to obtain short calculation times while maintaining accuracy. The accuracy of the combined model as it develops will continually be checked through EGS4 Monte Carlo calculations and, later into the project, with experimental dose distributions using a medical electron linear accelerator.