非晶硅电子射野影像装置在宫颈癌剂量验证中的应用
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摘要
目的:非晶硅电子射野影像装置(a-Si EPID)分别与Arc CHECK和二维电离室矩阵(PTW729)两种验证技术在宫颈癌剂量验证中的应用比较。方法:随机选取40例宫颈癌容积旋转调强技术(VMAT)和调强放射治疗技术(IMRT)病例。在相应的模体上分别设计出验证计划,将验证计划分为VMAT和IMRT两组,利用a-Si EPID和Arc CHECK验证VMAT计划,a-Si EPID和PTW729验证IMRT计划,在UNIQUE加速器上进行验证。采用γ分析方法(3%,3 mm,10%标准),比较两组验证计划的相对剂量与绝对剂量通过率和X、Y方向的profile。结果:VMAT组:Arc CHECK的绝对剂量通过率为(97.73±1.98)%,相对剂量通过率为(96.96±2.34)%;a-Si EPID的绝对剂量通过率为(97.58±1.88)%,相对剂量通过率为(98.13±1.47)%。IMRT组:PTW729的绝对剂量通过率为(98.48±1.89)%,相对剂量通过率为(97.32±1.56)%;a-Si EPID的绝对剂量通过率为(98.74±1.77)%,相对剂量通过率为(97.98±1.65)%。同时两组X、Y方向的profile理论与实测很相近,理论剂量分布图与实测计算剂量分布图在高低剂量点分布上重合度较高。结论:3种验证技术的结果在剂量学上没有明显差异,但a-Si EPID具有成像分辨率高、图像处理快捷、使用方便等优点。
Objective To compare the application of amorphous silicon electronic portal imaging device(a-Si EPID) and Arc CHECK, two-dimensional ionization chamber(PTW729) in the dose verification of cervical cancer. Methods The volumetric modulated arc therapy(VMAT) plans and intensity-modulated radiotherapy(IMRT) plans in 40 patients with cervical cancer were randomly selected. The verifiable plans were designed on corresponding phantoms, and were divided into VMAT group and IMRT groups. The a-Si EPID and Arc CHECK were used to verify VMAT plan, while a-Si EPID and PTW729 were used to verify IMRT plan. The verifications were performed on UNIQUE accelerator. The Gamma method(3%, 3 mm, 10%criterion) was adopted to compare the passing rate of relative dose and absolute dose, and the profile of X and Y directions between the different verification methods. Results In VMAT group, the passing rates of absolute dose and relative dose of Arc CHECK were(97.73 ± 1.98)% and(96.96 ± 2.34)%, respectively, while those of a-Si EPID were(97.58 ± 1.88)% and(98.13 ±1.47)%, respectively. In IMRT group, the passing rate of absolute dose and relative dose of PTW729 were(98.48±1.89)% and(97.32±1.56)%, respectively, while those of a-Si EPID were(98.74±1.77)% and(97.98±1.65)%. The calculated profile of X and Y direction was coincided with the actual one. The measured and calculated dose distribution had a high degree of coincidence at the distribution of high and low dose points. Conclusion No significant differences were found among Arc CHECK, PTW729 and a-Si EPID, but a-Si EPID has the advantages of higher resolution, more efficient image processing and convenience.
Objective To compare the application of amorphous silicon electronic portal imaging device(a-Si EPID) and Arc CHECK, two-dimensional ionization chamber(PTW729) in the dose verification of cervical cancer. Methods The volumetric modulated arc therapy(VMAT) plans and intensity-modulated radiotherapy(IMRT) plans in 40 patients with cervical cancer were randomly selected. The verifiable plans were designed on corresponding phantoms, and were divided into VMAT group and IMRT groups. The a-Si EPID and Arc CHECK were used to verify VMAT plan, while a-Si EPID and PTW729 were used to verify IMRT plan. The verifications were performed on UNIQUE accelerator. The Gamma method(3%, 3 mm, 10%criterion) was adopted to compare the passing rate of relative dose and absolute dose, and the profile of X and Y directions between the different verification methods. Results In VMAT group, the passing rates of absolute dose and relative dose of Arc CHECK were(97.73 ± 1.98)% and(96.96 ± 2.34)%, respectively, while those of a-Si EPID were(97.58 ± 1.88)% and(98.13 ±1.47)%, respectively. In IMRT group, the passing rate of absolute dose and relative dose of PTW729 were(98.48±1.89)% and(97.32±1.56)%, respectively, while those of a-Si EPID were(98.74±1.77)% and(97.98±1.65)%. The calculated profile of X and Y direction was coincided with the actual one. The measured and calculated dose distribution had a high degree of coincidence at the distribution of high and low dose points. Conclusion No significant differences were found among Arc CHECK, PTW729 and a-Si EPID, but a-Si EPID has the advantages of higher resolution, more efficient image processing and convenience.
引文
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[11]KIM Y L,LEE J W,CHOI K S,et al.Comparison of the performance between portal dosimetry and a commercial twodimensional array system on pretreatment quality assurance for volumetric-modulated arc and intensity-modulated radiation therapy[J].J Korean Phys Soc,2014,64(8):1207-1212.
[12]窦文,钟青松,龚剑,等.调强放射治疗射野和剂量的验证[J].中国医学物理学杂志,2012,29(1):3085-3087.DOU W,ZHONG Q S,GONG J,et al.Field sharp and dose verification of intensity modulated radiotherapy[J].Chinese Journal of Medical Physics,2012,29(1):3085-3087.
[2]MANS A,REMEIJER P,OLACIREGUIRUIZ I,et al.3D Dosimetric verification of volumetric-modulated arc therapy by portal dosimetry[J].Radiother Oncol,2010,94(2):181-187.
[3]DOBLER B,WEIDNER K,KOELBL O,et al.Commissioning of volumetric modulated arc therapy(VMAT)in a dual-vendor environment[J].Radiat Oncol,2011,99(1):86-89.
[4]BERTELSEN A,HANSEN C R,JOHANSEN J,et al.Single arc volumetric modulated arc therapy of head and neck cancer[J].Radiat Oncol,2010,95(2):142-148.
[5]CHANDRARAJ V,STATHAKIS S,MANICKAM R,et al.Consistency and reproducibility of the VMAT plan delivery using three independent validation methods[J].J Appl Clin Med Phys,2010,12(1):129-140.
[6]RAMMA U,K?HNA J,DOMINGUEZ R R,et al.Feasibility study of patient positioning verification in electron beam radiotherapy with an electronic portal imaging device(EPID)[J].Phys Med,2014,30(2):215-220.
[7]WOODRUFF H C,FUANGROD T,VAN U E,et al.First experience with real-time EPID-based delivery verification during IMRT and VMAT sessions[J].Int J Radiat Oncol Biol Phys,2015,93(3):516-522.
[8]FUANGROD T,ROWSHANFARZAD P,GREER P B,et al.A cine EPID based method for jaw detection and quality assurance for tracking jaw in IMRT/VMAT treatments[J].Phys Med,2015,31(1):16-24.
[9]ROXBY K J,CROSBIE J C.Pre-treatment verification of intensity modulated radiation therapy plans using a commercial electronic portal dosimetry system[J].Australas Phys Eng Sci Med,2010,33(1):51-57.
[10]BAWAZEER O,HERATH S,SARASANANDARAJAH S,et al.Electronic portal imaging device dosimetry for IMRT:a review on commercial available solutions[C].IFMBE Proceedings,2015,51:553-556.
[11]KIM Y L,LEE J W,CHOI K S,et al.Comparison of the performance between portal dosimetry and a commercial twodimensional array system on pretreatment quality assurance for volumetric-modulated arc and intensity-modulated radiation therapy[J].J Korean Phys Soc,2014,64(8):1207-1212.
[12]窦文,钟青松,龚剑,等.调强放射治疗射野和剂量的验证[J].中国医学物理学杂志,2012,29(1):3085-3087.DOU W,ZHONG Q S,GONG J,et al.Field sharp and dose verification of intensity modulated radiotherapy[J].Chinese Journal of Medical Physics,2012,29(1):3085-3087.