| 谭军文,龙雨松,贺先桃,等.多叶准直器复杂度指标对鼻咽癌容积旋转调强放疗计划γ通过率的影响[J].中华放射医学与防护杂志,2025,45(4):309-316.Tan Junwen,Long Yusong,He Xiantao,et al.Influence of the complexity metrics of the multi-leaf collimator on the γ-pass rate of volumetric modulated arc therapy plans for nasopharyngeal carcinoma[J].Chin J Radiol Med Prot,2025,45(4):309-316 |
| 多叶准直器复杂度指标对鼻咽癌容积旋转调强放疗计划γ通过率的影响 |
| Influence of the complexity metrics of the multi-leaf collimator on the γ-pass rate of volumetric modulated arc therapy plans for nasopharyngeal carcinoma |
| 投稿时间：2024-04-30 |
| DOI：10.3760/cma.j.cn112271-20240430-00166 |
| 中文关键词: VMAT γ通过率 复杂度指标 鼻咽癌 |
| 英文关键词:VMAT γ-passing rate Complexity metric Nasopharyngeal carcinoma |
| 基金项目:广西卫健委自筹经费科研课题(Z20200966);广西重点研发计划(桂科AB22035026) |
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| 中文摘要: |
| 目的 研究鼻咽癌容积旋转调强放疗(VMAT)计划的复杂度指标对γ通过率的影响。方法 选取60例鼻咽癌VMAT计划,测量计划的γ通过率,解析每个VMAT计划中所有控制点(CP)的多叶准直器(MLC)数据,统计平均射野面积(MFA)、平均叶尖间隙(ALG)、小野分数 (SAS),以及这三者考虑剂量权重(W)加权后的结果MFAW、ALGW、SASW;采用Pearson 法双变量相关性分析MLC复杂度指标与计划验证通过率的相关性,采用受试者工作特征曲线(ROC)分析来评估MLC复杂度指标对剂量验证结果的预测效果。结果 3%/3 mm、3%/2 mm、2%/2 mm标准下,60个VMAT计划的MFA与γ通过率呈正相关(r=0.82、0.79、0.72,P<0.05),MFAW与γ呈正相关(r=0.83、0.81、0.75,P<0.05);ALG与γ呈正相关(r=0.82、0.79、0.74,P<0.05),ALGW与γ呈正相关(r=0.83、0.81、0.77,P<0.05);SAS(0~1 cm)、SAS(1~2 cm)、SAS(2~3 cm)、SAS(3~4 cm)与γ呈负相关(r= -0.86、-0.82、-0.71、-0.84、-0.82、-0.72、-0.79、-0.79、-0.73、-0.30、-0.35、-0.42,P<0.05),SAS(4~5 cm)、SAS(5~6 cm)、SAS(6~40 cm)与之呈正相关(r=0.49、0.45、0.33、0.73、0.71、0.59、0.79、0.79、0.76,P<0.05),SASW的结果略强于SAS的结果。复杂度指标之间MFA与ALG呈正相关(r=0.98,P<0.05),ALG与SAS(0~1 cm)、SAS(1~2 cm)、SAS(2~3 cm)、SAS(3~4 cm) 呈负相关(r= -0.95、-0.94、-0.89、-0.39,P<0.05),与SAS(4~5 cm)、SAS(5~6 cm)、SAS(6~40 cm) 呈正相关(r=0.51、0.77、0.92,P<0.05),加权后的结果与之类似。ROC分析结果表明,MFA、MFAW、ALG、ALGW、SAS(0~1 cm)、SAS(1~2 cm)、SAS(2~3 cm)、SAS(6~40 cm)、SASW(0~1 cm)、SASW(1~2 cm)、SASW(2~3 cm)、SASW(6~40 cm)对预测剂量验证结果具有非常好的效果[受试者工作特征曲线下面积(AUC)>0.9,P<0.05]。结论 鼻咽癌VMAT计划验证通过率和MLC复杂度指标具有很强的相关性,相关指标对预测剂量验证结果具有非常好的效果;MLC形成的狭窄射野造成剂量计算和测量的不确定性增加是导致VMAT计划验证通过率降低的重要原因;该结果与放疗计划系统(TPS)建模的精度和剂量验证工具的准确度差异相关,可为相似问题提供参考。 |
| 英文摘要: |
| Objective To investigate the influence of the complexity metrics of the multi-leaf collimator (MLC) on the γ-pass rate of volumetric modulated arc therapy (VMAT) plans for nasopharyngeal carcinoma (NPC). Methods A total of 60 VMAT plans for NPC were selected to measure the γ-pass rate. The MLC data across all control points (CPs) in each VMAT plan were analyzed to calculate the mean field area (MFA), average leaf gap (ALG), small aperture score (SAS), and their corresponding weighted metrics including MFAW, ALGW, and SASW, considering dose weight (W). Pearson's bivariate correlation analysis was conducted to examine the correlations between MLC complexity metrics and the γ-pass rate. Moreover, the receiver operating characteristic (ROC) analysis was employed to assess the predictive efficacy of MLC complexity metrics on dose verification result. Results Under the 3%/3 mm, 3%/2 mm, and 2%/2 mm criteria, the MFA in the 60 VMAT plans exhibited a positive correlation with the γ-pass rate (r=0.82, 0.79, 0.72,P<0.05), and the MFAW was also positively correlated with the γ-pass rate (r=0.83, 0.81, 0.75,P<0.05). The ALG manifested a positive correlation with the γ-pass rate (r=0.82, 0.79, 0.74,P<0.05), as did the ALGW (r=0.83, 0.81, 0.77,P<0.05). The SAS(0-1 cm), SAS(1-2 cm), SAS(2-3 cm), and SAS(3-4 cm) displayed negative correlations with the γ-pass rate (r= -0.86, -0.82, -0.71, -0.84, -0.82, -0.72, -0.79, -0.79, -0.73, -0.30, -0.35, -0.42,P<0.05), whereas the SAS(4-5 cm), SAS(5-6 cm), and SAS(6-40 cm) showed positive correlations with the γ-pass rate (r=0.49, 0.45, 0.33, 0.73, 0.71, 0.59, 0.79, 0.79, 0.76,P<0.05). The outcomes of SASW reveal slightly stronger correlations than those of SAS. In terms of correlations among complexity metrics, a positive correlation was observed between MFA and ALG (r=0.98,P<0.05). ALG was negatively correlated with SAS(0-1 cm), SAS(1-2 cm), SAS(2-3 cm), and SAS(3-4 cm) (r= -0.95, -0.94, -0.89, -0.39,P<0.05), and positively correlated with SAS(4-5 cm), SAS(5-6 cm), and SAS(6-40 cm) (r=0.51, 0.77, 0.92,P<0.05). The weighted result mirrored these correlations. The ROC-derived analytical result indicate that MFA, MFAW, ALG, ALGW, SAS(0-1 cm), SAS(1-2 cm), SAS(2-3 cm), SAS(6-40 cm), SASW(0-1 cm), SASW(1-2 cm), SASW(2-3 cm), and SASW(6-40 cm) demonstrated exceptional predictive efficacy for dose verification result [Area under the curve (AUC)>0.9, P<0.05]. Conclusions The γ-pass rate of VMAT plans for NPC is strongly correlated with MLC complexity metrics, which demonstrate excellent predictive efficacy for dose verification result. The increased uncertainty in dose calculations and measurements caused by narrow fields generated by the MLC is a significant factor contributing to the reduced γ-pass rate of VMAT plans. This finding is associated with discrepancies in the precision of treatment planning system (TPS) modeling and the accuracy of dose verification tools, providing a reference for similar challenges. |
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