直肠癌术后调强放疗不同照射野数的剂量学研究

目的 通过比较不同照射野数治疗计划的计划靶区、肿瘤周围的正常组织及危及器官的剂量学特点、治疗时间及治疗费用方面的因素,探讨直肠癌术后调强放疗理想的治疗计划模式。方法 统一规定直肠癌术后调强放疗的临床靶区,设定计划靶区为临床靶区的外扩边界在X、Y和Z三个方分别为5、4、3 mm。应用治疗计划系统对不同照射野数5、7、9个照射野治疗计划的靶区剂量分布特点,机器跳数以及小肠、膀胱、双侧股骨头受照射体积、剂量进行比较。采用SPSS19.0统计软件包进行统计分析。结果 5、7、9个照射野治疗计划皆能满足临床剂量求。三种治疗计划中7个野、9个野在计划靶区剂量分布、剂量均匀性和适形度方面优于5个野,但从治疗时间实施治疗效率上看,5个野最短,7个野优于9个野。在对小肠保护方面,7个野、9个野优于5个野;膀胱保护方面,9个野优于7个野和5个野;在股骨头方面,5个野优于7个和9个照射野。结论 综合计划靶区剂量分布、肿瘤周围正常组织的保护、治疗时间及治疗费用四方面因素,建议在直肠癌术后调强放疗临床工作中,根据患者的具体情况与侧重点,选择合适的照射野数。

Dosimetric study of different radiation field numbers in postoperative intensity modulated radiation therapy for rectal cancer

Objective By comparing dosimetry characteristics of PTV and organs at risk, time of treatment and cost factors of different radiation field number treatment plans, we research on the most ideal mode for postoperative intensity modulated radiotherapy of rectal cancer (PIMRTRC).Methods The clinical target area of (PIMRTRC) was uniformly defined, and PTV was set as the external expansion boundary of the clinical target volume, which was 5 mm, 4 mm and 3 mm in X, Y and Z, respectively. Using TPS to calculate the dose distribution characteristics of target areas in different irradiation field numbers (5, 7, 9), we compared the irradiated volumes and dose levels of PTVs, bowls, bladders and femur heads respectively. SPSS19.0 statistical software package was used for statistical analysis.Results 5, 7 and 9 radiation field treatment plans can meet the clinical dose requirements. In the three modes of plans, 7 fields and 9 fields were superior to 5 fields in the dose distribution, dose uniformity and conformal degree of the planned target area, but in terms of the treatment time, 5 fields were the shortest and 7 fields were superior to 9 fields. In the protection of small intestine, 7 fields and 9 fields were better than 5 fields; In bladder protection, 9 fields were superior to 7 fields and 5 fields; In terms of femoral head, 5 fields were superior to 7 and 9 fields.Conclusion Based on the comprehensive planning of the dose distribution of PTV, the protection of the normal tissues around the tumor, the treatment time and the treatment cost, it is suggested to select the appropriate radiation field number according to the specific situation and focus of the patients in the clinical work of intensity-modulated radiation therapy for rectal cancer after surgery.