黄子珂,杨翠,王佳舟,胡伟刚,韩序.放疗工作环境辐射对Exradin W1闪烁体探测器测量立体定向治疗计划的影响[J].中华放射医学与防护杂志,2021,41(5):368-373
放疗工作环境辐射对Exradin W1闪烁体探测器测量立体定向治疗计划的影响
The effect of environmental radiation of radiotherapy workplace on stereotactic radiation therapy plan dose verification using an Exradin W1 scintillator detector
投稿时间:2020-11-27  
DOI:10.3760/cma.j.issn.0254-5098.2021.05.009
中文关键词:  塑料闪烁体探测器  剂量验证  立体定向放射治疗  质量保证
英文关键词:Plastic scintillator detector  Dose verification  Stereotactic radiation therapy plans  Quality assurance
基金项目:
作者单位E-mail
黄子珂 复旦大学附属肿瘤医院放射治疗中心 复旦大学上海医学院肿瘤系, 上海 200032  
杨翠 复旦大学附属肿瘤医院放射治疗中心 复旦大学上海医学院肿瘤系, 上海 200032  
王佳舟 复旦大学附属肿瘤医院放射治疗中心 复旦大学上海医学院肿瘤系, 上海 200032  
胡伟刚 复旦大学附属肿瘤医院放射治疗中心 复旦大学上海医学院肿瘤系, 上海 200032  
韩序 复旦大学附属肿瘤医院放射治疗中心 复旦大学上海医学院肿瘤系, 上海 200032 jimmyhan244@126.com 
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中文摘要:
      目的 研究放疗工作环境辐射对塑料闪烁体探测器Exradin W1进行立体定向放射治疗(SRT)计划绝对剂量验证的影响。方法 将立体验证模体(SDVP)的电子计算机断层(CT)影像扫描后导入计划系统,利用自制档铅分别在屏蔽或不屏蔽光电组件的条件下进行3 cm×3 cm至20 cm×20 cm的方形梯度射野照射、虚拟靶体积(PTV)非共面弧照射以及10例容积调强弧形立体定向放射治疗(VMAT SRT)临床计划验证,记录各测量值并对比分析环境辐射在不同条件下对剂量测量的影响。结果 光电组件的噪声效应随开放射野面积增大而增大,随光电组件与等中心距离增大而减小;非共面弧对光电组件噪声效应贡献随射野增大而增大,最大可达4.16%;临床SRT计划验证测量时,屏蔽前与屏蔽后与治疗计划系统(TPS)相对误差分别为(1.39±1.05)%和(0.59±1.03)%,差异具有统计学意义(t=-5.343,P<0.05);与A16小空气电离室实测结果相对误差分别为(1.22±1.56)%和(0.42±1.42)%,W1测量误差明显减少,差异具有统计学意义(t=-5.414,P<0.05)。结论 Exradin W1探测的测量结果与电离室及计划系统的计算结果一致度较好,但其准确度易受放疗工作环境辐射的影响。测量非共面照射时应将光电组件尽量摆放在远离辐射等中心位置,并予以适当遮挡或屏蔽,可有效提高测量准确性和稳定性,为临床精准放射治疗提供有力保障。
英文摘要:
      Objective To study the influence of environmental radiation of radiotherapy workplace on the stereotactic radiation therapy(SRT) plan absolute dose verification with plastic scintillator detector Exradin W1. Methods The computed tomography (CT) image of the stereotactic dose verification phantom (SDVP) was scanned and imported into the treatment planning system. Three schemes, including 3 cm×3 cm to 20 cm×20 cm square gradient field irradiation, virtual planning target volume(PTV) non-coplanar arcs irradiation and 10 cases of volumetric modulated arc radiotherapy SRT (VMAT SRT) clinical plan verification, were measured with or without a home-made shield over the photodiode. Measurements were recorded to analyze the impact of environmental radiation on dose measurement under different conditions. Results The noise effect of the photodiode increased with the the lager open field size, and decreased with the reduced distance between the photodiode and isocenter. The contribution of photodiode noise effect increase with the lager non-coplanar arc field size, with the largest up to 4.16%. As for the clinical SRT plan verification measurement, the relative difference between the SRT plan measurements and treatment planning system(TPS) before and after shielding were (1.39±1.05)% and (0.59±1.03)%, respectively (t=-5.343,P < 0.05). and for W1 vs. A16 microchamber was (1.22±1.56)% and (0.42±1.42)%, respectively (t=-5.414, P < 0.05). Conclusions The measurements of Exradin W1 are in good agreement with the TPS result and the ionization chamber measurements, but its accuracy is easily affected by the environmental radiation of radiotherapy workplace. To measure non-coplanar radiation, the photodiode should be placed as far away as possible from the isocenter and be properly shielded, which can effectively improve the accuracy and stability of the measurement and provide a strong guarantee for clinical precision radiotherapy.
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