子野数目对宫颈癌术后调强放疗计划剂量分布的影响

Influence of Sub-field Number on the Planning of Intensity-modulated Radiation Therapy in the Postoperative Adjuvant Radiotherapy of Cervical Cancer

目的探讨子野数目对宫颈癌术后调强放疗计划剂量分布的影响。方法选取宫颈癌术后患者20例,保持计划的优化目标参数不变,仅把多叶光栅子野数目改变为15、25、30、40、60,并为每例患者设计5个计划。比较各个计划间的靶区最大剂量、最小剂量、平均剂量、适形指数(CI)和均匀指数(HI),危及器官关注剂量受照体积占总体积的百分比(V_(30)、V_(40)、V_(50)),机器跳数。结果在所有的计划方案中,15子野的方案的临床靶区的CI、HI与其他方案比较差异均有统计学意义(P均<0.05)。直肠的V50随子野数目增加而减小(P<0.05)。机器跳数及治疗时间随子野数增加而增大(P均<0.05)。结论宫颈癌术后调强计划25子野能够满足临床剂量学要求,同时能有效减少治疗时间,可作为宫颈癌术后调强放疗计划设计应用参考值。

Objective To investigate the influence of sub-field number on the planning of intensity-modulated radiation therapy for postoperative adjuvant radiotherapy for cervical cancer. Methods Twenty patients with postoperative cervical cancer were studied, and the optimization target parameters of plan constant were fixed, while the number of the multi-leave collimators sub-field was changed to 15,25,30,40,60, and 5 plans were designed for every patient. The target maximum dose, minimum dose, mean dose, conformity index （CI） and homogeneity index （HI）, the percentage of dose irradiated volume of organ at risk from total volume （V30, V40, V50 ） and monitor unit among the plans were compared. Results With the increase in the number of sub-field,the CI and HI of planning target volume become better （ P 〈 0.05 ）. The monitor unit was increased with the increase of sub-field number. The V50 of rectum was decreased with the increase of sub-field number （ P 〈 0.05 ）. Conclusion The 25 sub-fields of intensity-modulated radiation therapy plan of postoperative cervical cancer can meet the requirements of clinical dosimetry, and reduce the treatment time effectively,it can be used as the reference value for intensity-modulated radiation therapy plan of postoperative cervical cancer.