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目的:探讨全中枢神经系统放疗(craniospinal irradiation,CSI)调强射野衔接方法,改善射野衔接处剂量分布的均匀性。方法:6例全中枢放射治疗患者,针对每位患者分别采用常规适形照射技术和调强射野叠加优化技术进行计划设计,比较2种方法衔接处剂量分布的优劣,并分析摆位误差对衔接区域剂量的影响。结果:与传统射野衔接技术相比,新方法衔接区域剂量均匀,胸段脊髓衔接优势更明显。中下段脊髓衔接区Min平均值常规组和调强组分别为63.9%、和98.2%,差异有统计学意义,t=14.91,P<0.01;Max平均值分别为115.1%和107.0%,差异有统计学意义,t=7.72,P<0.01;V95%平均值分别为93.8%和100.0%,差异有统计学意义,t=12.49,P<0.01;V110%平均值分别为28.7%和0,差异有统计学意义,t=6.47,P=0.01。±5mm头脚方向摆位误差引起的衔接区域脊髓中轴剂量变化由原来的160%～35%降低到110%～95%。Matrixx衔接区域实测剂量与计划系统的剂量分布基本一致,Gamma(3mm、3%)通过率为96.7%。结论:采用调强叠加优化技术进行射野衔接,可有效改善衔接区域的剂量均匀性。
OBJECTIVE: To investigate the method of craniospinal irradiation (CSI) intensity-adjusted radiological convergence in order to improve the uniformity of dose distribution at radiographic junction. Methods: Six patients with total central radiation therapy were enrolled in this study. The conventional conformal irradiation technique and the intensity-modulated radiation superposition technique were used for the planning design of each patient. The advantages and disadvantages of the dose distribution at the two methods were compared. Effect on the dose in the bridging area. Results: Compared with the traditional radiological techniques, the dose of the new method was even, and the superiority of thoracic spinal cord connection was more obvious. The average value of Min in the middle and lower spinal cord convergence area was 63.9% and 98.2% respectively in the conventional group and the tonifying group, with a significant difference (t = 14.91, P <0.01). The average Max values were 115.1% and 107.0% Statistical significance, t = 7.72, P <0.01; V95% average were 93.8% and 100.0%, respectively, the difference was statistically significant, t = 12.49, P <0.01; V110% average were 28.7% and 0, respectively Statistically significant, t = 6.47, P = 0.01. ± 5mm head-to-toe positioning error caused by the convergence of spinal cord axis changes from the original 160% to 35% to 110% to 95%. The measured dose of Matrixx junction area is basically the same as that of the planned system, and the passing rate of Gamma (3mm, 3%) is 96.7%. Conclusion: The combination of intensity adjustment and superposition optimization technique can effectively improve the uniformity of dose in convergence area.