头颈部肿瘤容积调强旋转放疗和适形调强放疗剂量学比较

A dosimetric comparison of volumetric modulated arc therapy with intensity modulated radiation therapy for head and neck cancer

目的比较头颈部肿瘤容积调强旋转放疗(VMAT)和适形调强放疗(IMRT)的剂量学差异。方法选取2019年1月至2019年12月安徽医科大学第一附属医院经病理证实的46例头颈部肿瘤患者,所有患者采取仰卧位做CT模拟。勾画两个处方剂量水平的计划靶区(PTV),PTV70和PTV54,35次分割。使用同步加量计划。每例患者分别制定VMAT和IMRT计划,比较两者的剂量学差异。结果VMAT计划PTV70的适形性指数(CI)95%高于IMRT计划(0.91±0.02 vs.0.86±0.06),差异有统计学意义(t=4.933,P=0.004)。VMAT计划PTV54的均质性指数(HI)95%优于IMRT(0.09±0.04 vs.0.26±0.02),差异有统计学意义(t=4.548,P=0.038)。VMAT的脊髓D1%低于IMRT(37.62±4.34 vs.40.93±7.45),差异有统计学意义(t=2.615,P=0.045)。VMAT的左腮腺剂量为(21.28±8.13)Gy,右腮腺剂量为(22.39±7.42)Gy,比IMRT[(22.73±11.42)Gy和(24.25±7.91)Gy]略低,但差异无统计学意义(t=0.703,P=0.322;t=1.134,P=0.315)。与IMRT相比,VMAT可大幅降低机器跳数(521±112 vs.2129±564),明显缩短患者治疗时间[(2.12±0.39)min vs.(9.18±2.62)min],差异均有统计学意义(t=18.957,P<0.001;t=18.213,P<0.001)。结论VMAT技术的剂量分布优于IMRT,危及器官受量降低,并且可减少机器跳数,缩短治疗时间。

Objective To compare the dosimetric differences between volumetric modulated arc therapy(VMAT)and intensity modulated radiation therapy(IMRT)for head and neck cancer.Methods From January 2019 to December 2019,46 cases of patients with head and neck cancer confirmed by pathology in the First Affiliated Hospital of Anhui Medical University were selected.All patients underwent CT-simulation in supine position.Planning target volumes(PTVs)were delineated for two dose levels of PTV70 and PTV54 in 35 equal fraction.Simultaneous integrated boost plan was generated for all patients and optimized with both techniques,VMAT and IMRT with similar planning objectives.The dosimetry differences between the two plans were compared.Results The conformity index(CI)95%of PTV70 in VMAT plan was higher than that in IMRT plan(0.91±0.02 vs.0.86±0.06),and the difference was statistically significant(t=4.933,P=0.004).The homogeneity index(HI)95%of PTV54 in VMAT plan was superior to that in IMRT(0.09±0.04 vs.0.26±0.02),and the difference was statistically significant(t=4.548,P=0.038).The spinal cord D1%of VMAT was lower than that in IMRT(37.62±4.34 vs.40.93±7.45),and the difference was statistically significant(t=2.615,P=0.045).The dose of left parotid gland in VMAT was(21.28±8.13)Gy and the dose of right parotid gland was(22.39±7.42)Gy,which were slightly lower than those in IMRT[(22.73±11.42)Gy and(24.25±7.91)Gy],but the differences were not statistically significant(t=0.703,P=0.322;t=1.134,P=0.315).Compared with IMRT,VMAT could significantly reduce the number of monitor units(521±112 vs.2129±564),and could significantly shorten the treatment time of patients[(2.12±0.39)min vs.(9.18±2.62)min],and the differences were statistically significant(t=18.957,P<0.001;t=18.213,P<0.001).Conclusion The dose distribution of VMAT technology is better than IMRT,the dose of organ at risk is reduced,the monitor unit is lesser,and the treatment time is shorter.