两种调强技术在全中枢放疗中骨髓剂量的比较

Comparison of bone marrow dose between two intense-modulated radiotherapy techniques for craniospinal irradiation

目的比较调强放疗技术(IMRT)和旋转调强放疗技术(VMAT)在全中枢放疗中骨髓剂量差异。方法选取10例在北京世纪坛医院进行全中枢放疗的患者CT图像,勾画靶区及危及器官,对所有病例分别设计IMRT和VMAT计划,对两种计划的靶区、骨髓及重要危及器官剂量差异进行统计分析。结果IMRT与VMAT的靶区适形度指数(CI)分别为0.900±0.012、0.903±0.008(P=0.484),均匀性指数(HI)分别为0.076±0.009、0.109±0.005(P<0.001)。两组椎骨V_(25)、V_(30)、D_(mean)分别为[(89.78±3.11)%、(85.52±3.09)%,P=0.001]、[(75.85±3.99)%、(71.27±3.83)%,P=0.002]、[(33.08±0.66)、(32.56±0.65)Gy,P=0.012],盆骨V_(20)、V_(25)分别为[(24.22±3.28)%、(23.73±3.42)%,P=0.032]、[(21.99±3.23)%、(20.28±3.19)%,P<0.001],颅骨D_(mean)比较差异无统计学意义(P>0.05)。两组双肺V_(5)、V_(20)、D_(mean)分别为[(57.74±7.28)%、(76.89±10.39)%,P<0.001]、[(4.19±0.86)%、(2.66±0.63)%,P<0.001]、[(7.25±0.59)、(8.09±0.53)Gy,P=0.004],左肾、右肾D_(mean)分别为[(5.09±0.85)、(9.70±1.49)Gy,P<0.001]、[(6.11±0.98)、(10.01±1.55)Gy,P<0.001],晶体D_(max)比较差异无统计学意义(P>0.05)。结论全中枢放疗中,对于椎骨的V_(25)、V_(30)、D_(mean)和盆骨的V_(20)、V_(25),VMAT计划比IMRT计划更低。两种计划在靶区和重要危及器官的剂量分布上各有优劣,均能满足临床治疗要求。

Objective To compare the dosimetry differences of bone marrow between intensity-modulated radiation therapy(IMRT)and volumetric modulated arc therapy(VMAT)in craniospinal irradiation.Methods The CT images of ten patients treated with craniospinal irradiation in Beijing Shijitan Hospital were selected.The target area and organ at risk were outlined.Then two types of radiotherapy plans(VMAT and IMRT)were designed for all the cases.The dose differences of the target area,bone marrow and important endangered organs between the two plans were statistically analyzed.Results The planning target volume the conformity indexes(CI)was 0.900±0.012,0.903±0.008(P=0.484),and homogeneity indexes(HI)of the IMRT group and VMAT group was 0.076±0.009,0.109±0.005(P<0.001)respectively.The V_(30),V_(25),D_(mean) of vertebrae in the two groups were[(75.85±3.99)%,(71.27±3.83)%,P=0.002],[(89.78±3.11)%,(85.52±3.09)%,P=0.001],and[(33.08±0.66),(32.56±0.65)Gy,P=0.012].The V_(25) and V_(20) of pelvis were[(21.99±3.23)%,(20.28±3.19)%,P<0.001]and[(24.22±3.28)%,(23.73±3.42)%,P=0.032].The D_(mean) of skull showed no statistical difference(P>0.05).The V_(5),V_(20) and D_(mean) of the double lung in the two groups were[(57.74±7.28)%,(76.89±10.39)%,P<0.001],[(4.19±0.86)%,(2.66±0.63)%,P<0.001],and[(7.25±0.59),(8.09±0.53)Gy,P=0.004].The D_(mean) of left kidney and right kidney were[(5.09±0.85),(9.70±1.49)Gy,P<0.001]and[(6.11±0.98),(10.01±1.55)Gy,P<0.001].There was no significant difference in D_(max) of lens(P>0.05).Conclusion In craniospinal irradiation,the V_(30),V_(25),D_(mean) of vertebra and V_(25),V_(20) of pelvis were lower in VMAT plan than those in IMRT plan.The two plans have their own advantages and disadvantages in the dose distribution of planning target volume and main organ at risk,and both of them can meet the clinical treatment requirements.