调强放疗技术在射野衔接中的应用研究
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摘要
目的研究应用调强放疗技术进行射野衔接时的最佳优化参数。方法选择9例需射野衔接的患者,分别取1、2、4、8 cm作为射野衔接过渡区域,同时优化并模拟摆位误差,研究计划重叠长度对靶区实际受照剂量的影响。为了获得线性剂量过渡曲线,强制定义线性剂量过渡处方,利用Base Plan技术分段优化,研究计划优化次序和摆位误差对靶区剂量的影响。靶区剂量评价指标取计划重叠区域95%和1%体积所受到的照射剂量D_(95%)和D_(1%)。结果单从计划角度分析,射野衔接长度越短,计划衔接处的靶区剂量分布越差,差异有统计学意义(F=144.890&7.878,P<0.05);摆位误差越大,射野衔接长度越小,靶区的实际受照剂量偏差越大,差异有统计学意义(F=34.887&37.403,P<0.05);射野衔接长度接近时,在对抗摆位误差对靶区剂量的影响方面,分段优化比同时优化更有优势,差异有统计学意义(t=9.974&5.357,P<0.05)。结论利用调强放疗技术对长靶区进行射野衔接时,计划重叠长度≥4 cm,并采用线性剂量过渡处方分段优化的设计方式,可减少摆位误差对靶区实际受照剂量的影响。
Objective To explore the best optimization parameters of IMRT in fi eld junction. Methods Nine patients who need fi eld junction received 36 treatment plans, including 1, 2, 4, 8 cm overlying-fi eld region. Plan A and plan B were optimized together, and the isocenters moved 3, 5 and 10 mm at the directions of head and foot to simulate and analyze the infl uences of setup errors and overlying-fi eld lengths on the dose distribution of the target. In order to assure a ramp-like dose profi le in the fi eld overlap region, the plan A was optimized fi rst, with dose prescription explicitly enforcing a ramp-like dose profi le. The plan B was done a fterwards, taking into account the dose contribution of the plan A. Results The shorter the overlying-field length, the worse the dose distribution of the target, without considering the setup errors(F=144.890 and 7.878, P<0.05), which was the same when considering the setup errors(F=34.887 and 37.403, P<0.05). A linear ramp-like dose profi le in treatment fi eld overlap regions could improve treatment plan robustness with respect to small shifts in patient position during the IMRT treatment(t=9.974 and 5.357, P<0.05). Conclusion The IMRT plans with the overlying-fi eld length ≥4 cm and ramp-like dose profi le can minimize dosimetric dependence on minor positional errors in patient set-up.
Objective To explore the best optimization parameters of IMRT in fi eld junction. Methods Nine patients who need fi eld junction received 36 treatment plans, including 1, 2, 4, 8 cm overlying-fi eld region. Plan A and plan B were optimized together, and the isocenters moved 3, 5 and 10 mm at the directions of head and foot to simulate and analyze the infl uences of setup errors and overlying-fi eld lengths on the dose distribution of the target. In order to assure a ramp-like dose profi le in the fi eld overlap region, the plan A was optimized fi rst, with dose prescription explicitly enforcing a ramp-like dose profi le. The plan B was done a fterwards, taking into account the dose contribution of the plan A. Results The shorter the overlying-field length, the worse the dose distribution of the target, without considering the setup errors(F=144.890 and 7.878, P<0.05), which was the same when considering the setup errors(F=34.887 and 37.403, P<0.05). A linear ramp-like dose profi le in treatment fi eld overlap regions could improve treatment plan robustness with respect to small shifts in patient position during the IMRT treatment(t=9.974 and 5.357, P<0.05). Conclusion The IMRT plans with the overlying-fi eld length ≥4 cm and ramp-like dose profi le can minimize dosimetric dependence on minor positional errors in patient set-up.
引文
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[12]Hadley A,Ding GX.A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment[J].Med Dosim,2014,39(4):314-319.
[13]Studenski M T,Shen X,Yu Y,et al.Intensity-modulated radiation therapy and volumetric-modulated arc therapy for adult craniospinal irradiation-a comparison with traditional techniques[J].Med Dosim,2013,38(1):48-54.
[14]田翠孟,张云泉,刘桂梅,等.肺癌放疗两种体膜使用方式的摆位误差分析[J].中国医疗设备,2015,30(12):120-122.
[15]汤艳萍,李令建.乳腺癌保乳术后调强放射治疗在CT图像引导下的摆位误差分析[J].中国医疗设备,2017,32(1):87-89.
[16]Strojnik A,Méndez I,Peterlin P.Reducing the dosimetric impact of positional errors in fi eld junctions for craniospinal irradiation using VMAT[J].Rep Pract Oncol Radiother,2016,21(3):232-239.
[2]von Bueren AO,Friedrich C,von Hoff K,et al.Metastatic medulloblastoma in adults:outcome of patients treated according to the HIT2000 protocol[J].Eur J Cancer,2015,51(16):2434-2443.
[3]谢秋英,石锦平,祁振宇,等.全中枢神经系统射野衔接方法研究[J].中华肿瘤防治杂志,2013,(15):1190-1193.
[4]杨玉刚,齐洪志,许林,等.适形与调强射野衔接技术在儿童全中枢神经系统放疗中的应用价值[J].中国医学物理学杂志,2016,(7):678-682.
[5]Al-Wassia RK,Ghassal NM,Naga A,et al.Optimization of craniospinal irradiation for pediatric medulloblastoma using VMAT and IMRT[J].J Pediatr Hematol Oncol,2015,37(7):e405-411.
[6]杨海芳,刘建平,张晓斌,等.全身定位技术在全脑全脊髓调强放疗中的应用研究[J].中国医疗器械杂志,2017,41(4):302-305.
[7]谢秋英,石锦平,张利文,等.全中枢神经系统调强放疗技术的应用[J].实用癌症杂志,2014,(6):712-715.
[8]Lin H,Ding X,Kirk M,et al.Supine craniospinal irradiation using a proton pencil beam scanning technique without match line changes for fi eld junctions[J].Int J Radiat Oncol Biol Phys,2014,90(1):71-78.
[9]马林.螺旋断层放疗系统的临床应用[J].中国医疗设备,2014,29(10):12-14.
[10]Langner UW,Molloy JA,Gleason JF Jr,et al.A feasibility study using Tomo Direct for craniospinal irradiation[J].J Appl Clin Med Phys,2013,14(5):104-114.
[11]Myers PA,Mavroidis P,Papanikolaou N,et al.Comparing conformal,arcradiotherapy and helical to motherapy in craniospinal irradiation planning[J].J Appl Clin Med Phys,2014,15(5):4724.
[12]Hadley A,Ding GX.A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment[J].Med Dosim,2014,39(4):314-319.
[13]Studenski M T,Shen X,Yu Y,et al.Intensity-modulated radiation therapy and volumetric-modulated arc therapy for adult craniospinal irradiation-a comparison with traditional techniques[J].Med Dosim,2013,38(1):48-54.
[14]田翠孟,张云泉,刘桂梅,等.肺癌放疗两种体膜使用方式的摆位误差分析[J].中国医疗设备,2015,30(12):120-122.
[15]汤艳萍,李令建.乳腺癌保乳术后调强放射治疗在CT图像引导下的摆位误差分析[J].中国医疗设备,2017,32(1):87-89.
[16]Strojnik A,Méndez I,Peterlin P.Reducing the dosimetric impact of positional errors in fi eld junctions for craniospinal irradiation using VMAT[J].Rep Pract Oncol Radiother,2016,21(3):232-239.