Abstract：Objective To investigate the setup error for nasopharyngeal carcinoma (NPC) patients with poor compliance using kV cone-beam computed tomography, and to calculate the expansion margin from the clinical target volume (CTV) to planning target volume (PTV). Methods In 45 NPC patients from 2013 to 2015, the setup error, 95% confidence interval (CI)-1 for random error, and PTV-1 value were calculated. Moreover, in 16 NPC patients with poor compliance based on five verifications (random error not within 95%CI-1), the setup error, 95%CI-2 for random error, and PTV-2 value were calculated. For the 16 special patients, PTV-1 and PTV-1 combined with PTV-2 were used to develop the plan-1 and plan-2, respectively. The dosimetric difference between plan-1 and plan-2 was evaluated. Results Both PTV-1 and PTV-2 had the largest expansion margin in the y direction. The CTV of plan-1 could not meet the requirement of the prescription dose after the setup error was introduced. Compared with plan-1, the V95% and D95 values for the CTV of plan-2 were increased by 6.26% and 4.43%, respectively. The D01 value was significantlylarger in plan-2 than in plan-1(P=0.005), which, however, met the clinical requirement. Conclusions In patients with poor compliance, the dose to target volume can be effectively elevated and the normal tissue can be spared from damage when PTV-1 combined with PTV-2 is selected as expansion margin.
Chen Jie,Zhang Wenxue,Wang Keqiang et al. Volumetric modulated arc therapy for nasopharyngeal carcinoma patients with poor compliance:setup error and expansion margin of target volume[J]. Chinese Journal of Radiation Oncology, 2016, 25(9): 971-974.
[1] van Herk M,Remeijer P,Lebesque JV.Errors and margins in radiotherapy[J].Semin Radiat Oncol,2004,14(1):52-64. [2] McKenzie A,van Herk M,Mijnheer B.Margins for geometric uncertainty around organs at risk in radiotherapy[J].Radiother Oncol,2002,62(3):299-307. [3] 孙晓欢,谭丽娜,马奎,等.摆位误差对VMAT计划剂量学验证的影响[J].中华放射肿瘤学杂志,2014,23(6):513-515. DOI:10.3760/cma.j.issn.1004-4221.2014.06.014. Sun XH,Tan LN,Ma K,et al. Effect of the setup error on the validation plan VMAT dosimetry[J].Chin J Radiat Oncol,2014,23(6):513-515.DOI:10.3760/cma.j.issn.1004-4221.2014.06.014. [4] 殷蔚伯,李晔雄,王绿化,等.肿瘤放射治疗手册[M].北京:中国协和医科大学出版社,2009:69-83. Yin WB,Li YX,Wang LH,et al. Radiation oncology handbook[M].Beijing:Peking union medical college press,2009:69-83. [5] Siebers JV,Keall PJ,Wu Q,et alEffect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans[J].Int J Radiat Oneol Biol Phys,2005,63:422-433. [6] 杨定宇.放疗技术员的工作职责[A]//胡逸民,杨定宇.肿瘤放射治疗技术[M].北京:北京医科大学中国协和医科大学联合出版社,1999:14. Yang DY.Job responsibilities of radiotherapy technician[A]//Hu YM,Yang DY.Tumor radiotherapy technology[M].Beijing:United Press of peking union medical college, beijing medical university,1999:14. [7] Gilbeau L,Octave-Prignot M,Loneol T,et al. Comparison of setup accuracy of three different thermoplastic masks for the treatment of brain and head and neck tumors[J].Radiother Oncol,2001,58(2):155-162. [8] 潘才住,潘建基,陈传本,等.应用电子射野影像装置实时纠正鼻咽癌调强放疗摆位误差研究[J].中华放射肿瘤学杂志,2009,18(5):341-345.DOI:10.3760/cma.j.issn.1004-4221.2009.05.341. Pan CZH,Pan JJ,Chen CHB,et al. Study on the position error of nasopharyngeal carcinoma intensity modulated radiation therapy in real-time by using electronic portal imaging device[J].Chin J Radiat Oncol,2009,18(5):341-345. DOI:10.3760/cma.j.issn.1004-4221.2009.05.341. [9] Zhang L,Garden AS,Lo J,et al. Multiple regions-of-interest analysis of setup uncertainties for head-and-neck cancer radiotherapy[J].Int J Radiat Oncol Biol Phys,2006,64(5):1559-1569. [10] 李明,吴志军,曹顾飞,等.基于XVI系统探讨鼻咽癌PTV外放范围及对放疗剂量的影响[J].中华生物医学工程杂志,2015,21(2):141-144.DOI:10.3760/cma.j.issn.1674-1927.2015.02.010. Li M,Wu ZHJ,Cao GF,et al. Based on XVI system to study the effect of PTV and radiotherapy dose in nasopharyngeal carcinoma patients[J].J Mode Clin Med Bioengineer,2015,21(2):141-144.DOI:doi:10.3760/cma.j.issn.1674-1927.2015.02.010. [11] Thilmann C,Nill S,Tucking T,et alCorrection of patient positioning errors based on in-line cone beam CTs:clinical implementation and first experiences[J].Radiat Oncol,2006,1:16. [12] Tham IW,Hee SW,Yeo RM,et al. Treatment of nasopharyngeal carcinoma using intensity-modulated radiotherapy-the national cancer centre singapore experience[J].Int J Radiat Oncol Biol Phys,2009,75(5):1481-1486. DOI:http://dx.doi.org/10.1016/j.ijrobp.2009.01.018. [13] 王鑫,胡超苏,应红梅,等.摆位系统误差对鼻咽癌放疗剂量分布的影响[J].中国癌症杂志,2008,18(8):620-625. Wang X,Hu CHS,Ying HM,et al. Effect of position system errors on dose distribution of radiotherapy for nasopharyngeal carcinoma[J].Chin Oncol,2008,18(8):620-625. [14] 中国鼻咽癌临床分期工作委员会.2010鼻咽癌调强放疗靶区及剂量设计指引专家共识[J].中华放射肿瘤学杂志.2011,20(4):267-269.DOI:10.3760/cma.j.issn.1004-4221.2011.04.001.Committee on clinical staging of nasopharyngeal carcinoma in China. Expert consensus on target area and dose design guidelines for 2010 nasopharyngeal carcinoma patients with radiotherapy[J].Chin J Radiat Oncol,2011,20(4):267-269. DOI:10.3760/cma.j.issn.1004-4221.2011.04.001.
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