基于电子射野影像装置的肺部肿瘤立体定向体部放射治疗在体三维剂量验证模体研究及临床应用

Study on phantom testing and clinical application of lung tumor SBRT based on EPID-based in-vivo 3D dose verification system

目的:探讨基于电子射野影像装置的肺部肿瘤立体定向体部放射治疗在体三维剂量验证模体研究及临床应用。方法:通过电子射野影像装置在体三维剂量验证系统,在静态和动态模体上测试不同立体定向体部放射治疗照射技术计划(静态调强、滑窗调强、旋转调强及适形、动态适形旋转治疗),比较在体三维剂量分布5种剂量/距离一致性标准(5%/2 mm、3%/3 mm、3%/2 mm、3%/1 mm、2%/2 mm)的γ通过率,检测计划照射精度,并对临床肺立体定向体部放射治疗病例进行在体三维剂量验证靶区和危及器官剂量体积分析。结果:模体研究结果显示,在静态模体中静态调强、滑窗调强、旋转调强照射方式γ通过率差异无统计学意义(P均>0.05),在动态模体中静态调强计划γ通过率偏低,其他照射方式计划之间相近。临床应用结果显示,临床病例在体三维剂量验证3%/3 mm标准明显低于治疗前剂量验证结果,剂量体积直方图分析中体积变化大的危及器官存在较大剂量偏差。结论:基于电子射野影像装置的肺部肿瘤立体定向体部放射治疗在体三维剂量验证,能为肺部肿瘤立体定向体部放射治疗治疗期间剂量投照的准确性提供有效安全性检查,可应用于临床,为自适应治疗提供基础。

Aim:To evaluate different irradiation treatment plans using an in-vivo 3D dose verification system based on the electronic portal imaging device(EPID) using phantom,and clinical application of stereotactic body radiation therapy(SBRT).Methods:The study utilized two types of phantoms(static and dynamic phantoms).An in-vivo 3D dose verification system based on EPID was employed to capture images of various irradiation planning techniques,including static intensity-modulated radiotherapy(sIMRT),dynamic intensity-modulated radiotherapy(dIMRT),volumetric modulated arc therapy(VMAT),conventional radiotherapy(CRT),and dynamic conventional arc therapy(Dynarc).Gamma passing rate was compared under different dose/distance tolerance for various conditions(5%/2 mm,3%/3 mm,3%/2 mm,3%/1 mm,2%/2 mm).In clinical cases,dose-volume histograms were utilized to analyze the dose distribution of the target volume and organs at risk(OARs).Results:In the static phantoms,there were no significant differences in the gamma passing rate between VMAT,sIMRT and dIMRT.However,in the dynamic phantoms,the gamma passing rate of the sIMRT plan was lower compared with other delivery methods.For clinical cases,the gamma passing rate for in-vivo 3D dose verification(3%/3 mm) was still considerably lower than that of pretreatment.In dose volume histogram analysis,OARs with significant volume changes exhibited considerable dose deviations.Conclusions:The implementation of this procedure can enhance SBRT patients′ safety,and serve as a preliminary step towards clinical adaptive radiotherapy.