Yuan Lulin, Wu Q Jackie, Yin Fangfang, Li Ying, Sheng Yang, Kelsey Christopher R, Ge Yaorong
Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.
Phys Med Biol. 2015 Mar 7;60(5):1831-43. doi: 10.1088/0031-9155/60/5/1831. Epub 2015 Feb 6.
The selection of the incident angles of the treatment beams is a critical component of intensity modulated radiation therapy (IMRT) planning for lung cancer due to significant variations in tumor location, tumor size and patient anatomy. We investigate the feasibility of establishing a small set of standardized beam bouquets for planning. The set of beam bouquets were determined by learning the beam configuration features from 60 clinical lung IMRT plans designed by experienced planners. A k-medoids cluster analysis method was used to classify the beam configurations in the dataset. The appropriate number of clusters was determined by maximizing the value of average silhouette width of the classification. Once the number of clusters had been determined, the beam arrangements in each medoid of the clusters were designated as the standardized beam bouquet for the cluster. This standardized bouquet set was used to re-plan 20 cases randomly selected from the clinical database. The dosimetric quality of the plans using the beam bouquets was evaluated against the corresponding clinical plans by a paired t-test. The classification with six clusters has the largest average silhouette width value and hence would best represent the beam bouquet patterns in the dataset. The results shows that plans generated with a small number of standardized bouquets (e.g. 6) have comparable quality to that of clinical plans. These standardized beam configuration bouquets will potentially help improve plan efficiency and facilitate automated planning.
由于肿瘤位置、肿瘤大小和患者解剖结构存在显著差异，治疗束入射角的选择是肺癌调强放射治疗（IMRT）计划的关键组成部分。我们研究了建立一小套标准化射束集用于计划的可行性。通过从经验丰富的计划者设计的60个临床肺部IMRT计划中学习射束配置特征来确定射束集。使用k-中心点聚类分析方法对数据集中的射束配置进行分类。通过最大化分类的平均轮廓宽度值来确定合适的聚类数量。一旦确定了聚类数量，每个聚类的中心点中的射束排列就被指定为该聚类的标准化射束集。这个标准化射束集用于对从临床数据库中随机选择的20个病例重新进行计划。通过配对t检验，将使用射束集的计划的剂量学质量与相应的临床计划进行评估。六聚类的分类具有最大的平均轮廓宽度值，因此最能代表数据集中的射束集模式。结果表明，用少量标准化射束集（如6个）生成的计划与临床计划具有相当的质量。这些标准化射束配置集可能有助于提高计划效率并促进自动化计划。
