3种调强技术在局部晚期直肠癌术前新辅助短程放疗的剂量学比较

Comparison of dosimetry among 3 kinds of intensity-modulated technology in locally advanced rectal cancer preoperative neoadjuvant short-term radiotherapy

目的 比较静态调强放疗(sIMRT)、动态调强放疗(dIMRT)和容积旋转调强放疗(VMAT)在局部晚期直肠癌术前新辅助短程放疗的剂量学差异。方法 共16例局部晚期直肠癌患者纳入研究。分别设计3种调强放疗计划(7F-sIMRT,7F-dIMRT,VMAT),采用三维计划验证系统进行剂量验证,比较3种技术之间计划靶区和危及器官剂量学、机器跳数(MU)、伽马通过率差异。结果 3组计划靶区98%、2%、50%靶区体积剂量(D_(98)、D_(2)、D_(50))、最大剂量(D_(max))、最小剂量(D_(min))、均匀性指数(HI)、适形度指数(CI)差异有统计学意义(P<0.05),平均剂量(D_(mean))、107%处方剂量覆盖的体积(V_(107%))无明显差异(P>0.05)。3组左、右侧股骨头15 Gy剂量曲线覆盖的体积(V_(15))、D_(max),膀胱25、20、10 Gy剂量曲线覆盖的体积(V_(25)、V_(20)、V_(10))、D_(min)、D_(mean),小肠V_(25)、V_(20)、V_(15)、V_(10)、D_(min)、D_(mean),阴茎V_(10)、D_(min)、D_(mean),会阴D_(min)、D_(mean)差异有统计学意义(P<0.05)。sIMRT组MU明显低于dIMRT组和VMAT组(P<0.05)。在不同评判标准下,sIMRT组伽马通过率均高于dIMRT组和VMAT组(P<0.05)。结论 3种放疗技术各有优缺点,应根据临床需求选择合适的直肠癌术前新辅助短程放疗技术。

Objective To compare the differences of dosimetry in locally advanced rectal cancer preoperative neoadjuvant short-term radiotherapy among the static intensity-modulated radiotherapy(sIMRT),dynamic intensity-modulated radiotherapy(dIMRT) and volume-modulated arc therapy(VMAT).Methods Sixteen patients with locally advanced rectal cancer were enrolled in this study.The three kinds of intensity-modulated radiotherapy plans(7F-sIMRT,7F-dIMRT,VMAT) were designed respectively.The dose verification was performed by the three-dimensional plan verification system.The differences in the plan targeted region, dosimetry of organs at risk, machine hop count(MU) and γ pass rates were compared among the three techniques.Results The doses in 98%,2% and 50% target volume(D_(98),D_(2),D_(50)) of the plan target region, maximal dose(D_(max));minimal dose(D_(min));homogeneity index(HI) and conformal index(CI) had statistical differences among the three groups(P<0.05).There was no statistically significant difference in the mean dose(D_(mean)) and volume covered by 107% prescription dose(V_(107%)) among the three groups(P>0.05).The volume covered by 15 Gy dose curve of left and right femoral head(V_(15)),volume of bladder covered by 25,20,10 Gy dose curves(V_(25),V_(20),V_(10)),D_(min),D_(mean),small intestine V_(25),V_(20),V_(15),V10D_(min)and D_(mean),penis V_(10),D_(min)and D_(mean) and perineum D_(min)and D_(mean) had statistical differences among 3 groups(P<0.05).MU in the sIMRT group was significantly lower than those in the dIMRT group and VMAT group(P<0.05).In the different evaluation standards, the gamma passing rate in the sIMRT group was higher than that in the dIMRT group and VMAT group(P<0.05).Conclusion Three radiotherapy techniques have their own advantages and disadvantages, and the suitable rectal cancer preoperative neoadjuvant short-term radiotherapeutic techniques should beselected according to the clinical need.