VMAT计划复杂性的定量评估方法探讨  

The quantitative method to evaluate the plan complexity of volumetric-modulated arc therapy

作　　者：李光俊[1] 李衍龙 钟仁明[1] 肖江洪[1] 王雪桃[1] 柏森[1] 

机构地区：[1]四川大学华西医院肿瘤中心放射物理技术中心,成都610041

出　　处：《中华放射肿瘤学杂志》2015年第6期684-687,共4页Chinese Journal of Radiation Oncology

基　　金：国家自然科学基金项目（81101697）

摘　　要：目的：提出新的定量评估指标———弧形野调制复杂度分数（ AMCS），并分析6种量化计划复杂性指标对VMAT剂量验证的影响。方法定量计算127例患者VMAT计划复杂性指标：平均射野面积（ ABA）、平均叶片路径（ ALT）、平均射野宽度（ ABW）、调制复杂度分数（ MCS）、叶片路径？调制复杂度分数（ LTMCS）和AMCS。采用Delta4系统测量VMAT剂量验证γ通过率。 Pearson法分析ABA、ALT、ABW、MCS、LTMCS和AMCS与3 mm／3％下γ通过率相关性，以及6个指标间的相互关系。结果 ABA、ALT、ABW、MCS、LTMCS和AMCS平均值分别为（73．5±24．1） cm2、（69．6±9．8） cm、（3．63±1．03） cm、0．33±0．05、0．14±0．04和0．16±0．05，且均与γ通过率相关（P＝0．000），其中AMCS与γ通过率相关性最大（ r＝0．637）；AMCS＜平均值时γ通过率＜95％的射野比为60．7％，＞平均值时为9．9％。 ABA、ABW与ALT无相关性（P＝0．720、0．073），其余指标间均相关（P＝0．000～0．003）。结论 AMCS指标是一种适合用于定量评估VMAT计划复杂性的方法，可用于预测VMAT剂量验证结果，在VMAT计划审核中用于比较多个计划的复杂度以帮助选择最佳计划。Objective To study a new quantitative method—arc？beam modulation complexity score （ AMCS） to evaluate the plan complexity of volumetric？modulated arc therapy （ VMAT） ,and the effect of the six metrics on VMAT dosimetric verification. Methods The six metrics,which contain the average of beam area （ ABA ） , the average of leaf travel （ ALT ） , the average of beam width （ ABW ） , the modulation complexity score （ MCS ） , the leaf travel and modulation complexity score （ LTMCS ） and AMCS, was calculated to quantify the plan complexity of VMAT for 127 selected patients. Delta4 system was used for verifying the VMAT plans and the γ pass rate was calculated. The relativity between the six metrics and the pass rates or between the 6 parameters were analyzed with Pearson method. Results The average of ABA, ALT,ABW,MCS,LTMCS and AMCS were （73.5±24. 1） cm2,（69.6±9. 8） cm,（3.63±1. 03） cm,0.33± 0. 05,0.14±0. 04 and 0.16± 0. 05,respectively. A negative correlation was observed for ALT and the pass rate,and the other metrics had a positive correlation with it （P=0. 000）.The correlation between AMCS and the pass rate was the strongest with Pearson’ s （ r=0. 637） in the six metrics. The percentage of arcs with a pass rate lower the 95% was 60. 7 when AMCS is lower than the average,while it was 9. 9% when AMCS is higher than the average. Both ABA and ABW had no significant correlation with ALT （ P=0. 720,0. 073） , and the other metrics had significant correlations （ P=0. 000？0. 003 ） . Conclusions AMCS is a suitable quantitative metric to evaluate the plan complexity of VMAT, and could be used to forecast the result of dosimetric verification of VMAT plans. It could be also use to compare the multiple VMAT plans complexity and help us to choose the best plan.

关 键 词：容积调强弧形疗法 γ通过率 弧形野调制复杂度分数 

分 类 号：R730.55[医药卫生—肿瘤]