Cui Weijie, Dai Jianrong
Department of Radiation Oncology, National Cancer Center/National Clinical Research Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, People's Republic of China.
Biomed Phys Eng Express. 2024 Sep 18;10(6). doi: 10.1088/2057-1976/ad6c52.
. Dual layer MLC (DMLC) has have been adopted in several commercial products and one major challenge in DMLC usage is leaf sequencing for intensity-modulated radiation therapy (IMRT). In this study we developed a leaf sequencing algorithm for IMRT with an orthogonal DMLC.. This new algorithm is inspired by the algorithm proposed by Dai and Zhu for IMRT with single layer MLC (SMLC). It iterately determines a delivery segment intensity and corresponding segment shape for a given fluence matrix and leaves residual fluence matrix to following iterations. The segment intensity is determined according to complexities of residual fluence matrix when segment intensity varies from one to highest level in the matrix. The segment intensity and corresponding segment shape that result least complexity was selected. Although the algorithm framework is similar to Dai and Zhu's algorithm, this new algorithm develops complexity algorithms along with rules for determining segment leaf settings when delivered with orthogonal DMLC. This algorithm has been evaluated with 9 groups of randomly generated fluence matrices with various dimensions and intensity levels. Sixteen fluence matrices generated in Pinnacle system for two clinical IMRT examples were also used for evaluation. Statistical information of leaf sequences generated with this algorithm for both the random and clinical matrices were compared to the results of two typical algorithms for SMLC: that proposed by Dai and Zhu and that proposed by Bortfled.. Compared to the SMLC delivery sequences generated with Dai and Zhu's algorithm, the proposed algorithm for orthogonal DMLC delivery reduces the average number of segments by 27.7% ∼ 41.8% for 9 groups of randomly generated fluence matrices and 10.5% ∼ 41.7% for clinical ones. When comparing MU efficiency between different algorithms, it is observed that the proposed algorithm performs better than the optimal efficiency of SMLC delivery when dealing with simple fluence matrices, but slightly worse when handling complex ones.. This new algorithm generates leaf sequences for orthogonal DMLC delivery with high delivery efficiency in terms of number of leaf segments. This algorithm has potential to work well with orthogonal DMLC for improving efficiency or quality of IMRT.
双层多叶准直器（DMLC）已被应用于多种商业产品中，而DMLC在使用中的一个主要挑战是调强放射治疗（IMRT）的叶片排序。在本研究中，我们开发了一种用于正交DMLC的IMRT叶片排序算法。这种新算法受到了戴和朱提出的单层多叶准直器（SMLC）的IMRT算法的启发。它针对给定的注量矩阵迭代地确定一个输送段强度和相应的段形状，并将剩余注量矩阵留待后续迭代。当段强度在矩阵中从1变化到最高水平时，根据剩余注量矩阵的复杂度来确定段强度。选择导致复杂度最低的段强度和相应段形状。尽管算法框架与戴和朱的算法相似，但这种新算法开发了复杂度算法以及在使用正交DMLC输送时确定段叶片设置的规则。该算法已通过9组随机生成的具有不同维度和强度水平的注量矩阵进行评估。在Pinnacle系统中为两个临床IMRT示例生成的16个注量矩阵也用于评估。将该算法为随机矩阵和临床矩阵生成的叶片序列的统计信息与SMLC的两种典型算法的结果进行了比较：戴和朱提出的算法以及博尔特菲尔德提出的算法。与使用戴和朱的算法生成的SMLC输送序列相比，所提出的正交DMLC输送算法对于9组随机生成的注量矩阵，段的平均数量减少了27.7%至41.8%，对于临床矩阵减少了10.5%至41.7%。在比较不同算法之间的MU效率时，可以观察到，在处理简单注量矩阵时，所提出的算法比SMLC输送的最佳效率表现更好，但在处理复杂注量矩阵时略差。这种新算法在叶片段数量方面为正交DMLC输送生成了具有高输送效率的叶片序列。该算法有潜力与正交DMLC配合良好，以提高IMRT的效率或质量。
