Objective: To discuss dose distribution at various aspects of the mono-isocenter irradiation technique in intensity-modulated radiation therapy (IMRT) for the treatment of patients with upper and mid esophagus cancer in order to provide reference value for clinical application. Methods: 20 cases diagnosed as upper and mid esophagus cancer were selected from our hospital during 2014-2016, and the first target used half field IMRT in the up area while the second target used half field IMRT in the down area. One was the relative dose verification of interface slice used with the film dosimeter; the another was the center point dose verification used with the ionization chamber and adapter module; the third one was the relative dose verification of the coronal plane used with the two dimensional matrix Mapcheck dosimeter; and the dose verification results of IMRT used with the mono-isocenter irradiation technique were statistical analyzed. Results: The film verification indicated that didn't have cold-hot point and the results accorded with verification; the center point dose verification results indicated that the degree of deviation was less than 3%; the relative dose verification of the coronal plane showed that passing rate was above 98.04% under 3 mm/3%; and was above 98.77% under 4 mm/4%. These results indicated the dose passing rate of radiation field of all patients were above 98%. Conclusion: The dose distribution at various aspects of the mono-isocenter IMRT can pass the verification requirements, which accord with the demands of clinical treatment and is worthy for application and promotion.%目的:探讨胸中上段食管癌患者同中心上下半野调强放射治疗(IMRT)在各个层面的剂量分布,为临床应用提供参考.方法:选取20例确诊为胸中上段食管癌患者,上下半段靶区分别对应设计制作上、下半野IMRT计划.通过胶片剂量仪进行衔接层面的相对剂量验证、指形电离室及适配模体对中心点剂量验证,以及通过二维矩阵电离室Mapcheck进行冠状面的相对剂量验证,对同中心上下进行2个半野IMRT不同层面的剂量分布统计分析.结果:上下分野衔接层面的胶片验证结果<5%,无剂量冷热点出现,符合剂量验证;中心点剂量验证结果为偏差度均<3%;冠状面的相对剂量验证在3 mm/3%条件下通过率>98.04%,4 mm/4%条件下通过率>98.77%.结果表明,所有患者的照射野剂量通过率均高于98%.结论:同中心上下半野IMRT技术在各个层面的剂量分布均能够通过验证要求,符合临床治疗需要.
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