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目的:探讨模拟CT扫描时使用对比剂与否对鼻咽癌GTV勾画的准确性和一致性的影响。方法:选择病理确诊和按照标准程序临床分期的连续鼻咽癌病例10例,在治疗体位下行鼻咽、颈部CT平扫(C-)和增强CT扫描(C+)。CT图像传入TPS(Pinnacle3,Version8.0dp1),每份图像导入4次(C-和C+各4次)。对GTV-、GTV+两组数据进行配对样本t检验。结果:GTV-、GTV+与GTVco的比值R分别为0.88±0.38和0.92±0.39。增强CT中AP、SI、LR最大径的CV值分别为10.43±8.55、7.15±8.53和9.60±4.62,而在平扫CT中分别为9.21±6.49、6.35±9.09和6.33±5.38(P值分别为0.711、0.808和0.029)。GTV+、GTV-体积的CV值分别为30.52±16.16和28.26±11.65(P=0.523)。增强CT中各项观察指标的CV值均大于平扫CT(CV越大代表变异越小)。结论:对比剂的使用使得增强CT在显示鼻咽癌原发灶方面比CT平扫图像更为清晰。不同医生在C+图像上勾画GTV的变异度低于C-图像上的变异度,且与GTVco具有更好的一致性。
Objective: To investigate the effect of contrast agent or not on the accuracy and consistency of GTV sketching for nasopharyngeal carcinoma in simulated CT scan. Methods: Ten cases of consecutive nasopharyngeal carcinoma with pathological diagnosis and clinical staging according to standard procedure were selected. Nasopharyngeal and cervical CT scan (C - CT) and enhanced CT scan (C +) were performed at the position of treatment. The CT images were passed to TPS (Pinnacle 3, Version 8.0dp1) and each image was imported 4 times (C- and C + 4 times each). Paired sample t-test was performed on GTV-, GTV + two sets of data. Results: The ratios of GTV-, GTV + and GTVco were 0.88 ± 0.38 and 0.92 ± 0.39, respectively. The CV values of maximum diameters of AP, SI and LR in enhanced CT were 10.43 ± 8.55, 7.15 ± 8.53 and 9.60 ± 4.62, respectively, while in plain CT were 9.21 ± 6.49, 6.35 ± 9.09 and 6.33 ± 5.38, respectively 0.711, 0.808 and 0.029). The CV values of GTV + and GTV-volume were 30.52 ± 16.16 and 28.26 ± 11.65, respectively (P = 0.523). Enhanced CT in all indicators of the CV values were greater than plain CT (CV, the greater the smaller the representative variation). CONCLUSIONS: The use of contrast agents makes enhanced CT more clear than plain CT images in displaying primary tumors of NPC. The variability of GTV delineated by different doctors on C + images is lower than the variability on C-images and has better consistency with GTVco.