【摘要】 目的研究食管癌患者应用静态调强放疗(static intensity modulate radiotherapy,sIMRT)和容积调强弧形放疗(volumetric modulated are therapy,VMAT)计划剂量学差异。方法收集37例食管癌单纯放疗患者CT模拟定位图像。对每一例患者的CT图像都设计sIMRT和VMAT两种计划,评估大体肿瘤靶区体积(gross tumor volume,GTV)、计划靶区体积(planning target volume,PTV)和危及器官的剂量学参数,两种计划的比较采用配对t检验。结果与sIMRT相比,VMAT计划的GTV的D98、D2、Dmean的剂量较低(分别为60.03±1.23 vs 62.46±1.03,64.83±0.91 vs 66.08±1.01,63.62±1.28 vs 64.07±1.08,P<0.001、P=0.001、P=0.021),PTV的D98、D2的覆盖度、最大剂量均低于sIMRT(分别为58.39±1.03 vs 58.51±0.57,65.92±1.57vs 66.17±1.25,P=0.314、P=0.230)。但PTV的V105较sIMRT低(t=-8.216,P<0.001),二者有明显差异,显示VMAT较好。适形指数和均一性指数相似(t=-0.147,P=0.884;t=2.56,P=0.89)。在危及器官比较中,VMAT的双肺V20、V30、肺平均剂量(mean lung dose,MLD)明显低于sIMRT(t=-12.690,P<0.001;t=-2.870,P=0.007;t=-3.659,P<0.001),差异均有统计学意义。脊髓、心脏照射量较低,但二者差异没有统计学意义(P=0.743,P=0.519)。机器跳数分别为572.33、754.95,VMAT的机器跳数比sIMRT减少24%(P<0.001)。结论 VMAT较sIMRT显著改善靶区剂量,PTV-V105较sIMRT低,可使双肺V20、V30的剂量降低,尤其是可显著缩短治疗时间,提高治疗效率,VMAT在食管癌的应用具有良好的发展前景。更多还原

【Abstract】 Objective To compare the feasibility of using volumetric modulated arc therapy(VMAT)or static intensity-modulated radiotherapy(IMRT)to treat advanced esophageal neoplasm. Methods A consecutive series of 37 patients newly diagnosed with esophageal neoplasm was analyzed by computed tomography,and the resulting images were input into the oncentra planning system to generate protocols for IMRT and VMAT. All 37 patients received both types of treatment. Dose-volume histograms were generated to compare gross tumor volume(GTV),planning target volume(PTV) and exposure of at-risk organs. Different results for each method were assessed for statistical significance using the paired t-test. Results VMAT gave slightly but not significantly higher values than IMRT for PTV-D98(58.39±1.03 vs 58.51±0.57,P=0.314)and PTV-D2(65.92±1.57 vs 66.17±1.25,P=0.230). VMAT was associated with significantly lower GTV D98(60.03±1.23 vs 62.46±1.03,P<0.001),D2(64.83±0.91 vs 66.08±1.01,P=0.001),and Dmean(63.62±1.28 vs 64.07±1.08,P=0.021). VMAT also gave significantly lower PTV-V105coverage(t=-8.216,P<0.001). The two methods were associated with similar conformity index(t=-0.147,P=0.884),homogeneity index(t=2.56,P=0.89),spinal dose(P=0.743)and heart dose(P=0.519). VMAT was associated with lower lung V20 than IMRT(t=-12.690,P<0.001),as well as lower lung V30(t=-2.870,P=0.007)and lower mean lung dose(t=-3.659,P=0.001). Mean MU was 24% lower with VMAT than with IMRT(572.33 vs 754.95). Conclusion In patients with esophageal neoplasms,VMAT can provide equivalent or superior dose distributions compared to IMRT,and it can generate more and better GTV hotspots. VMAT is also associated with lower lung V20 and V30,lower MU,and higher delivery efficiency. These findings suggest that VMAT has strong potential for treating esophageal cancer.更多还原