容积旋转调强放疗计划中优化分组角度对头颈部单、双侧靶区的影响

doi:10.19438/j.cjoms.2024.06.011

摘要/Abstract

摘要： 目的： 研究Monaco计划系统中优化分组角度（increment of gantry, INC）对容积旋转调强放疗（volumetric modulated arc therapy,VMAT）计划的影响,为肿瘤放射治疗的计划优化参数提供参考。方法： 选择2022年1月—12月上海交通大学医学院附属第九人民医院收治的需术后放疗的腮腺癌和舌癌患者各15例。其中,舌癌组采用双侧照射,腮腺癌组采用单侧照射。除更改Inc参数外,同一病例的计划设计参数均不改变,计划剂量优化结果要求达到临床使用要求。分别采用20、25、30、35、40优化分组角度进行对比,并以30的优化分组角度所做出的计划作为参考计划。统计并比较靶区的体积剂量D_98%、D_5%和D_2%,以及适形度指数(conformity index,CI)与均匀性指数(homogeneity index,HI)。比较不同Inc参数计划导致的危及器官体积剂量参数和计划跳数。采用SPSS 22.0软件包对数据进行统计学分析。结果： 双侧照射的舌癌组计划结果显示,Inc参数设置为30时,靶区的归一性更好。与对照组相比,其余Inc参数计划的靶区HI均有统计学意义;除Inc35计划外,其余CI均有统计学差异。危及器官方面,除左侧腮腺外,右侧腮腺、喉选择优化角度为30的效果最佳（P<0.05）,左侧腮腺则20和35的效果最佳（P<0.05）。单侧照射的腮腺癌组计划结果显示,优化角度选择为30时表现更佳,靶区的归一性更好。HI评价结果存在统计差异（P<0.05）,同侧中耳Inc为20,25表现较为优秀（P<0.05）,喉组织角间距为20、25、40时结果更为优秀（P<0.05）,下颌骨角间距为25时表现最为优秀（P<0.05）,脊髓、脑干以及对侧腮腺无显著差异。所有计划的跳数随着Inc的增大而减小,单侧照射和双侧照射计划跳数均无统计学差异。结论： 容积旋转调强放疗计划优化角度需要根据照射范围和肿瘤类型进行合理选择,Inc默认值30在双侧照射的舌癌靶区计划表现出更多优势;但对于单侧照射的腮腺肿瘤,除靶区存在一定优势外,其他优势并不明显。

关键词: 头颈肿瘤, 放疗, 容积旋转调强, 优化分组角度, 单、双侧靶区

Abstract: PURPOSE: To investigate the effect of increment of gantry(INC) in the Monaco treatment planning system on VMAT plan, and provide reference for optimizing the parameters of radiotherapy plan. METHODS: A total of 15 patients with parotid gland cancer and 15 patients with tongue cancer requiring postoperative radiotherapy were selected from Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from January to December 2022. Bilateral irradiation was used in tongue cancer group and unilateral irradiation in parotid gland cancer group. Except for changing the Inc parameters, the planning design parameters of the same case should not be changed, and the optimization results of planned dose should meet the requirements of clinical use. The optimization grouping angles of 20, 25, 30, 35, and 40 were compared, and the plan made from the optimization grouping angle of 30 was used as a reference plan. D_98%,D_5% and D_2%, as well as the conformity index(CI) and homogeneity index(HI) were calculated and compared. The organ at risk dose parameters and planned jumps caused by different Inc parameter plans were also compared. SPSS 22.0 software package was used for data analysis. RESULTS: The results of tongue cancer group with bilateral irradiation showed that when the Inc parameter was set to 30, the normalization of the target area was better. Compared with the control group, the target area HI of the other Inc parameter plans were significantly different. Except for the Inc35 plan, all other CI had significant differences. In terms of organ endangerment, except for the left parotid gland, the optimal angle of 30 for the right parotid gland and larynx was the best(P<0.05). There was no significant difference in the spinal cord, while 20 and 35 for the left parotid gland were the best(P<0.05). The results of the parotid gland cancer group plan with unilateral irradiation showed that the optimal angle of 30 had better performance and better normalization of the target area. There was significant difference (P<0.05) in the evaluation results of HI. The ipsilateral middle ear Inc was 20, and 25 performed better(P<0.05). The results were better when the distance between laryngeal tissue angles was 20, 25, and 40(P<0.05), and the best performance was when the distance between mandibular angles was 25(P<0.05). There was no significant difference in the spinal cord, brain stem, and contralateral parotid gland. The number of hops for all plans increased with the increment of Inc, and there was no significant difference in the monitor units for both unilateral and bilateral irradiation plans. CONCLUSIONS: The Inc selection of volumetric modulated arc therapy plan needs to be reasonable based on the irradiation range and tumor type. The default value of Inc is 30, which shows more advantages in the tongue cancer target area plan with bilateral irradiation. But for parotid gland tumors with unilateral irradiation, except for certain advantages in the target area, other advantages are not significant.

Key words: Head and neck tumor, Radiotherapy, Volumetric modulated arc therapy, Increment of gantry, Unilateral and bilateral target

中图分类号:

R739.8

石慧烽, 涂文勇, 毕帆. 容积旋转调强放疗计划中优化分组角度对头颈部单、双侧靶区的影响[J]. 中国口腔颌面外科杂志, 2024, 22(6): 584-589.

SHI Hui-feng, TU Wen-yong, BI Fan. Influence of increment of gantry in volumetric modulated arc therapy plan on unilateral and bilateral target volumes of head and neck[J]. China J Oral Maxillofac Surg, 2024, 22(6): 584-589.

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