基于刚性配准的剂量分布对齐方法  

Dose distribution alignment method based on rigid registration

作　　者：韦健 张纬诚 闫冰 陈春花 汪晖[1] WEI Jian;ZHANG Weicheng;YAN Bing;CHEN Chunhua;WANG Hui(Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;University of Science and Technology of China,Hefei 230026,China;The First Affiliated Hospital of University of Science and Technology of China,Hefei 230001,China)

机构地区：[1]中国科学院合肥物质科学研究院,合肥230031 [2]中国科学技术大学,合肥230026 [3]中国科学技术大学第一附属医院,合肥230001

出　　处：《辐射研究与辐射工艺学报》2023年第4期58-65,共8页Journal of Radiation Research and Radiation Processing

摘　　要：Gamma(γ)分析是剂量验证、剂量分布比较最重要的手段,由于不同剂量分布的坐标系定义/方向,基准点设置不一致,进行γ分析时往往要对待比较的剂量分布进行对齐,而目前常用的γ分析软件的对齐手段简单,在处理大照射野剂量分布时有显著错误,严重影响了剂量分析比较的准确性。二维剂量分布对齐的要求是在只进行平移、旋转等空间变换,从而达到两张剂量图上相应剂量点的空间位置一致。因为不同点之间的距离在对齐过程中必须是不变的,所以,本研究将对齐问题转化为刚性配准问题。本文采用基于归一化互相关的刚性配准方法,将治疗计划系统计算的剂量分布图与实际测量的剂量分布图进行配准,并输出配准后相应的平移量。选取36组计划系统和实测中心点一致的pinnacle3治疗计划系统设计的静态调强质量保证数据,其中,18组为小照射野,另18组为大照射野,使用PTW VeriSoft软件分别计算其在3%/3 mm、3%/2 mm、2%/2 mm通过标准下γ通过率。对于小照射野,直接计算与VeriSoft对齐后和刚性配准后的不同标准γ通过率结果均基本相当,其中在3%/3 mm通过标准下,VeriSoft对准后和刚性配准后与直接计算的γ通过率平均差异分别为0.5%和0.3%。对于大照射野,与直接计算的γ通过率结果相比,18组病例在VeriSoft对齐后于3%/3 mm、3%/2 mm、2%/2 mm通过标准下的γ通过率平均差异分别为17.1%、23.3%和28.3%,均呈现较大差异。而刚性配准后与直接计算在3%/3 mm、3%/2 mm和2%/2 mm标准下γ通过率的平均差异分别为0.4%、1.1%和2.3%,平均差异均较小。刚性配准解决了VeriSoft在处理大照射野剂量分布时存在显著错误的问题,其可以作为放射治疗计划剂量验证时一种适用于不同照射野剂量分布对齐的方法。Gamma(γ)analysis is the most important method for dose verification and dose distribution comparison.Because of the inconsistency of the coordinate system definitions and directions of different dose distributions and the inconsistent reference point settings,inγanalysis,the dose distributions should often be aligned for comparison.However,the alignment method of the current commonly usedγanalysis software is extremely simple,and there are significant errors in processing the dose distribution of the large radiation field,which seriously affect the accuracy of the dose analysis and comparison.Aligning the two-dimensional dose distribution requires performing spatial transformations such as translation and rotation to achieve the same spatial position of the corresponding dose points on the two dose maps.Because the distance between different points must be constant during this alignment process,in this study,the alignment problem is transformed into a rigid registration problem.A rigid registration method based on normalized cross-correlation is used to register the dose distribution map calculated using a treatment planning system with the actually measured dose distribution map and output the corresponding translation amount after registration.36 groups of static intensity-modulated quality assurance data designed using the pinnacle3 treatment planning system,whose planning system is consistent with the measured center point,are selected;18 groups are small irradiation fields,and the other 18 groups are large irradiation fields.PTW VeriSoft software is used to calculate theγpassing rate under 3%/3 mm,3%/2 mm,and 2%/2 mm pass standards separately.For small irradiation fields,the results of the direct calculation of different standardγpassing rates after alignment with VeriSoft and rigid registration are identical.Among them,under the 3%/3 mm pass standard,the results of VeriSoft alignment and rigid registration are compared with those directly calculated,the average differences inγpassing rate are 0.5%and

关 键 词：γ分析 归一化互相关 VeriSoft 刚性配准 剂量分布比较 

分 类 号：TL13[核科学技术—核能科学]