Langer M, Brown R, Urie M, Leong J, Stracher M, Shapiro J
Harvard Joint Center for Radiation Therapy, Boston, MA 02115.
Int J Radiat Oncol Biol Phys. 1990 Apr;18(4):887-93. doi: 10.1016/0360-3016(90)90413-e.
The problem of choosing weights for beams in a multifield plan which maximizes tumor dose under conditions that recognize the volume dependence of organ tolerance to radiation is considered, and its solution described. Structures are modelled as collections of discrete points, and the weighting problem described as a combinatorial linear program (LP). The combinatorial LP is solved as a mixed 0/1 integer program with appropriate restrictions on normal tissue dose. The method is illustrated through the assignment of weights to a set of 10 beams incident on a pelvic target. Dose-volume restrictions are placed on surrounding bowel, bladder, and rectum, and a limit placed on tumor dose inhomogeneity. Different tolerance restrictions are examined, so that the sensitivity of the target dose to changes in the normal tissue constraints may be explored. It is shown that the distributions obtained satisfy the posed constraints. The technique permits formal solution of the optimization problem, in a time short enough to meet the needs of treatment planners.
考虑了在多野计划中为射束选择权重的问题，即在认识到器官对辐射耐受性的体积依赖性的条件下使肿瘤剂量最大化，并描述了其解决方案。将结构建模为离散点的集合，并将加权问题描述为组合线性规划（LP）。组合LP作为混合0/1整数规划来求解，并对正常组织剂量有适当限制。通过为入射到盆腔靶区的一组10个射束分配权重来说明该方法。对周围的肠、膀胱和直肠设置剂量体积限制，并对肿瘤剂量不均匀性设置限制。研究了不同的耐受性限制，以便探索靶区剂量对正常组织约束变化的敏感性。结果表明，所获得的分布满足所提出的约束条件。该技术允许在足够短的时间内对优化问题进行形式化求解，以满足治疗计划者的需求。
