【作者】 王健；

【导师】 金人超；

【作者基本信息】 华中科技大学 ， 计算机应用技术， 2011， 硕士

【摘要】 调强放疗(IMRT)是一种高精度先进的放射治疗手段。IMRT能达到在对肿瘤周围关键组织最少照射的情况下达到对肿瘤更高的照射剂量。如何达到直线加速器的最小的剂量照射输出和最少的多页准直器叶片移动成为强度图矩阵分解的主要目标。通过达到这类目标可以提高放疗的效果,减少放疗时间,降低病人治疗时痛楚,延长机器寿命,总之,优化目标的达成,实际意义非凡。通过对各种强度矩阵分解算法的详细研究,而挑选可适应度高,优化结果令人满意的网络流图方法对强度矩阵进行分解。在对网络图算法的研究中,通过实现调强放疗的强度矩阵分解的优化,提出三点改进:首先,对网络图算法的网络图H的递归约束和一些令外的算法中的普遍用到的网络最大流算法进行改进,将其从一般的最快SPFA网络流算法提升到使用更为迅速的动态规划模型求解。不仅解决了SPFA算法频繁调用出去队列带来的效率损失,并且将算法复杂度从O ( n2)降低至O (n)。从根本上解决了大量约束计算的瓶颈问题。其次,对网络图算法的在高维的强度矩阵分解中存在的频繁递归问题,这些频繁调用递归很大程度影响了放疗的分解效率。通过对原始的完全递归算法进行合理的递归次数限制来增进算法效率。最后,对于放疗多页准直器中存在的射线散射,衍射,特别是舌槽效应,我们设计子野选择优化算法,在网络流算法的基础上改进算法的有序选择每行的子野状态,变成有约束选择最优算法达到优化子野形状达到增强放疗效果目的。实验结果表明以上三点改进在IMRT强度矩阵分解中取得不错的效果,时间复杂度的降低,放疗实施效率的提高,放疗剂量的准确性的提升均表明不错的改进效果。更多还原

【Abstract】 IMRT(Intensity Modulated Radiotherapy) was a accuracy machine to be used for cancer treating, The most importantly, IMRT can issued the possibility of higher intensity of radiation of tumor and better protection of vital tissue around. The intensity map can be linear divided into kinds of 0-1 matrix, from where our target is to choose the lest TNMU(total number of Monitor unit) and NS(Number of Segment)Through the comparing of some kinds of intensity Map decomposition algorithm, the network flow algorithm is the best choice for its wide adoption, applauded result. In the researching of intensity Map network flow decomposition algorithm, propose three improvements in the detail of the algorithm.First, in the network flow algorithm, the algorithm for computing the max flow of each node of network is commonly used in the constriction and some other constriction computing, we promoted the algorithm from SPFA(Shortest Path Fastest Algorithm) to Dynamic programming,decreased the complication from O ( n2) to O (n).Second, For network flow algorithm in decomposition of high-dimension intensity matrix, frequent recursion existing in computing cause quite a waste of time, Compared to the original completely recursion algorithm, we used reasonable recursion number limit to enhance the efficiency of the algorithm.Final, The negative effects of scattering, diffraction, tongue and grooves effect cause the IMRT radiation lost, Design a segment selection optimization algorithm to optimize the shape to enhance radiation effect purposeThe result of experiment showed some good improvements, the time complication was reduced, the efficiency of the whole algorithm is enhanced, and Accuracy of radiotherapy is more precise.更多还原