中华放射医学与防护杂志

夏校春,陆中杰,王佳浩,葛迦,严森祥,宁丽华.浸润型胸腺瘤术后单能与混合能量光子束调强放疗计划剂量学分析[J].中华放射医学与防护杂志,2015,35(6):471-474

浸润型胸腺瘤术后单能与混合能量光子束调强放疗计划剂量学分析

Analysis of dosimetric results of postoperative intensity modulated radiation therapy using single-energy or mixed-energy photons in invasive thymoma patients

投稿时间：2015-02-14

DOI：10.3760/cma.j.issn.0254-5098.2015.06.017

中文关键词: 混合能量光子束调强放射治疗浸润型胸腺瘤体积剂量直方图

英文关键词:Mixed-energy photons IMRT Invasive thymoma Dose volume histogram

基金项目:

作者	单位	E-mail
夏校春	312300绍兴市上虞中医医院放射科
陆中杰	浙江大学医学院附属第一医院放疗科
王佳浩	浙江大学医学院附属第一医院放疗科
葛迦	浙江大学医学院附属第一医院放疗科
严森祥	浙江大学医学院附属第一医院放疗科	phlzj@hotmail.com
宁丽华	浙江大学医学院附属第一医院放疗科

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中文摘要:

目的比较浸润型胸腺瘤术后患者单能与混合能量光子束调强放射治疗(IMRT)计划之间剂量学差异,探讨混合能量光子束计划在临床的应用价值。方法随机抽取12例胸腺瘤术后病例的CT定位图像,在治疗计划系统上勾画临床靶体积(CTV)并外扩为计划靶体积(PTV)、危及器官(OAR)及其他正常组织。每个病例分别制定6和10 MV与混合能量光子束的3种固定野调强放疗(FF-IMRT)计划,优化与计算剂量后统计各种计划的机器跳数(MU),并使用剂量体积直方图(DVH)工具比较PTV的体积剂量、适形指数(CI)、均匀指数(HI)和OAR剂量。结果 PTV近似最大剂量D_2%混合能量光子束计划优于6 MV光子束(t=3.107,P <0.05);6 MV光子束HI与混合能量光子束计划比较,差异有统计学意义(t=2.924,P<0.05);CI三者之间差异均有统计学意义。6 MV计划的MU大于10 MV及混合光子束计划。双侧肺V₅、V₁₀、V₂₀、V₃₀和平均剂量(D_mean)指标各个类型计划之间大部分差异有统计学意义,且混合能量光子束计划优于其他两种计划。心脏V₃₀、V₄₀指标6 MV与混合光子计划的结果接近,但均优于10 MV光子束的计划。结论混合能量光子束IMRT计划如果合理选择射野角度和射野数量,依据入射角度选择光子束的能量,可充分利用低能及高能光子束的不同特点,总体上可以改善IMRT计划的质量,对于浸润型胸腺瘤术后病例具有一定的临床参考价值。

英文摘要:

Objective To compare the dosimetric results of postoperative intensity modulated radiation therapy (IMRT) using single-energy or mixed-energy photons in invasive thymoma patients. Methods Simulation CT images were acquired and clinical target volume (CTV), planning target volume (PTV) and organs at risk (OARs) were defined. Three sets of fixed-field IMRT planning were generated using 6 MV, 10 MV and mixed 6/10 MV photons for each case. Monitor Units (MUs) for each plan were recorded after optimization, and parameters of PTV such as conformity index (CI), homogeneity index (HI) and dose to OARs were evaluated on dose-volume histograms. Results Near-Maximal dose (D_2%) received by PTV was better in mixed-energy IMRT as compared with 6 MV(t=3.107, P<0.05). HI was better in mixed-energy than in 6 MV(t=2.924,P<0.05). There were statistically significant differences in CI among three IMRT plans. MU was higher in 6 MV than in both 10 MV and mixed-energy IMRT. The percentages of lung volumes receiving 5 Gy (V₅),10 Gy(V₁₀), 20 Gy (V₂₀), 30 Gy(V₃₀) and the mean lung dose (D_mean)were also significantly different in most plans. V₃₀and V₄₀ of the heart were comparable between 6 MV and mixed energy plans but better than in 10 MV plan. Conclusions If the reasonable choice of beam angles and number, and capability of energy selection according to beam directions, with combined advantages of low and high energy photons, mixed IMRT plans can improve the quality of IMRT plans in general and has clinical potential for postoperative radiotherapy of invasive thymomas.

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