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[目的]探讨调强放疗计划过程中,不同医生勾画脊髓轮廓的不确定性及其对剂量的影响。[方法]由8位放疗医生对8例接受调强放疗的鼻咽癌患者CT图像逐例分别勾画脊髓轮廓,保持治疗计划其他参数不变,分别计算不同医生勾画脊髓的体积、剂量体积直方图(DVH)和最大剂量。[结果]不同医生勾画的脊髓体积差异显著(P<0.05),脊髓体积标准偏差最大的一例达到38.4%,最小也达到17.1%。脊髓DVH曲线主体部分基本重叠,而尾端长短不同,说明脊髓平均剂量接近,但最大剂量差异大(P<0.01)。最大剂量标准偏差变化范围6.8%～15.2%。[结论]危及器官(如脊髓)的勾画问题应引起到重视。在放射治疗计划设计中,除靶区的勾画以外,对危及器官尤其是边界不清楚的危及器官的勾画方法亦应进行规范。
[Objective] To explore the uncertainty of different contours drawn by different doctors and their effect on dosage during intensity-modulated radiotherapy planning. [Methods] 8 spinal radiologists treated 8 patients with nasopharyngeal carcinoma undergoing intensity modulated radiotherapy to outline the spinal cord contours. The other parameters of the treatment plan were kept unchanged. The volume, the volume of dose histogram (DVH) and maximum dose. [Results] The volume of spinal cord delineated by different doctors was significantly different (P <0.05). The highest standard deviation of spinal volume was 38.4% and the lowest was 17.1%. Spinal DVH curve of the main part of the basic overlap, while the length of the tail end, indicating that the average dose of spinal cord approach, but the maximum dose difference (P <0.01). The maximum dose standard deviation range of 6.8% to 15.2%. [Conclusion] The delineation of endangering organ (such as spinal cord) deserves attention. In the design of radiation therapy plans, in addition to the outline of the target area, the methods of delineating the endangered organs that endanger the organs, especially the borders, should also be regulated.