左侧乳腺癌保乳术后瘤床同步推量螺旋断层放疗与容积调强放疗的剂量学研究

Dosimetric study of helical tomotherapy and volumetric modulated arc therapy simultaneous integrated boost for patients receiving breast-conserving surgery of left breast

目的比较左侧乳腺癌保乳术后螺旋断层放疗(HT)与容积调强放疗(VMAT)的剂量学特点及优势。方法选取云南省肿瘤医院放疗科2016年5月至2019年5月收治的24例左侧乳腺癌保乳术后患者,对同一患者分别设计HT计划和VMAT计划,并对两种放疗计划的靶区剂量及危及器官剂量体积参数进行比较分析。结果HT和VMAT两种放疗计划计划肿瘤体积(PGTV)的D_(2%)[(59.68±0.46)Gy vs.(60.06±0.20)Gy,t=-4.229,P<0.001]、D_(98%)[(57.46±0.44)Gy vs.(57.20±0.07)Gy,t=2.912,P<0.001]、适形度指数(CI)(0.80±0.05 vs.0.76±0.04,t=4.079,P<0.001)、均匀性指数(HI)(0.04±0.01 vs.0.05±0.00,t=-5.505,P<0.001)差异均有统计学意义;而D50%[(58.77±0.46)Gy vs.(58.75±0.11)Gy,t=0.179,P=0.859]差异无统计学意义。两种放疗计划计划靶体积(PTV)的D50%[(51.99±0.39)Gy vs.(52.39±0.36)Gy,t=-5.278,P<0.001]、D_(98%)[(49.46±0.29)Gy vs.(48.35±0.46)Gy,t=9.538,P<0.001]、HI(0.19±0.01 vs.0.21±0.01,t=-7.538,P<0.001)差异均有统计学意义,D_(2%)[(59.13±0.64)Gy vs.(59.09±0.46)Gy,t=0.511,P=0.614]、CI(0.83±0.04 vs.0.82±0.04,t=1.637,P=0.115)差异无统计学意义。在危及器官方面,HT和VMAT的左肺V5[(57.90±1.42)%vs.(52.40±5.74)%,t=4.812,P<0.001]、V_(20)[(22.40±2.17)%vs.(18.40±3.16)%,t=5.573,P<0.001]、D_(mean)[(12.71±0.55)Gy vs.(11.46±1.26)Gy,t=4.963,P<0.001],右肺D_(mean)[(3.42±0.27)Gy vs.(2.49±0.24)Gy,t=13.310,P<0.001],右侧乳腺的D_(mean)[(4.41±0.50)Gy vs.(3.12±0.65)Gy,t=10.326,P<0.001],心脏V_(30)[(0.55±0.37)%vs.(1.24±1.11)%,t=-4.020,P=0.001]、D_(mean)[(4.68±0.62)Gy vs.(3.83±0.88)Gy,t=7.335,P<0.001],左心房D_(mean)[(2.53±0.31)Gy vs.(2.16±0.28)Gy,t=5.488,P<0.001],右心房D_(mean)[(2.77±0.43)Gy vs.(2.20±0.30)Gy,t=7.103,P<0.001],右心室D_(mean)[(5.10±0.72)Gy vs.(3.72±0.94)Gy,t=9.802,P<0.001],脊髓D_(2%)[(14.79±2.73)Gy vs.(5.42±2.23)Gy,t=14.788,P<0.001]差异均具有统计学意义;两种放疗计划左心室D_(mean)[(5.10±1.19)Gy vs.(4.80±1.54)Gy,t=1.250,P=0.224]差异无统计学意义。结论HT计划和VMAT计划均能满足治疗要求,HT计划能提供更好的靶区适形性和剂量均匀性,而危及器官方面VMAT计划更具优势,HT计划仅在高剂量区受照方面表现出优势。

Objective To compare the dosimetric characteristics of helical tomotherapy(HT)and volumetric modulated arc therapy(VMAT)after left breast conserving surgery.Methods Twenty-four patients with left breast cancer after breast-conserving surgery who were admitted to the Department of Radiation Oncology of Tumor Hospital of Yunnan Province from May 2016 to May 2019 were selected.The HT plan and the VMAT plan were designed for the same patient.The target dose and the dose volume parameters of organs at risk were compared and analyzed in the two radiotherapy plans.Results There were significant differences in the D_(2%)[(59.68±0.46)Gy vs.(60.06±0.20)Gy,t=-4.229,P<0.001],D_(98%)[(57.46±0.44)Gy vs.(57.20±0.07)Gy,t=2.912,P<0.001],conformity index(CI)(0.80±0.05 vs.0.76±0.04,t=4.079,P<0.001)and homogeneity index(HI)(0.04±0.01 vs.0.05±0.00,t=-5.505,P<0.001)of the planning gross tumor volume(PGTV)between the HT and VMAT plans.However,there was no significant difference in the D50%[(58.77±0.46)Gy vs.(58.75±0.11)Gy,t=0.179,P=0.859].There were significant differences in the D50%[(51.99±0.39)Gy vs.(52.39±0.36)Gy,t=-5.278,P<0.001],D_(98%)[(49.46±0.29)Gy vs.(48.35±0.46)Gy,t=9.538,P<0.001]and HI(0.19±0.01 vs.0.21±0.01,t=-7.538,P<0.001)of the planned target volume(PTV)between the two plans.However,there were no significant differences in the D_(2%)[(59.13±0.64)Gy vs.(59.09±0.46)Gy,t=0.511,P=0.614]and CI(0.83±0.04 vs.0.82±0.04,t=1.637,P=0.115).In terms of organs at risk,there were significant differences in the V5[(57.90±1.42)%vs.(52.40±5.74)%,t=4.812,P<0.001],V_(20)[(22.40±2.17)%vs.(18.40±3.16)%,t=5.573,P<0.001]and D_(mean)[(12.71±0.55)Gy vs.(11.46±1.26)Gy,t=4.963,P<0.001]of left lung,D_(mean)of right lung[(3.42±0.27)Gy vs.(2.49±0.24)Gy,t=13.310,P<0.001],D_(mean)of right breast[(4.41±0.50)Gy vs.(3.12±0.65)Gy,t=10.326,P<0.001],V_(30)[(0.55±0.37)%vs.(1.24±1.11)%,t=-4.020,P=0.001]and D_(mean)of heart[(4.68±0.62)Gy vs.(3.83±0.88)Gy,t=7.335,P<0.001],D_(mean)of left atrium[(2.53±0.31)Gy vs.(2.16±0.28)Gy,t=5.488,P<0.001],D_(mean)of right atrium[(2.77±0.43)Gy vs.(2.20±0.30)Gy,t=7.103,P<0.001],D_(mean)of right ventricle[(5.10±0.72)Gy vs.(3.72±0.94)Gy,t=9.802,P<0.001]and D_(2%)of spinal cord[(14.79±2.73)Gy vs.(5.42±2.23)Gy,t=14.788,P<0.001]between HT and VMAT plans.There was no significant difference in the D_(mean)of left ventricle[(5.10±1.19)Gy vs.(4.80±1.54)Gy,t=1.250,P=0.224].Conclusion Both the HT plan and the VMAT plan can meet the treatment requirements.The HT plan can provide better target area conformity and dose uniformity.The VMAT plan has more advantages in terms of organs at risk.The HT plan shows an advantage only in exposure to high-dose area.