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目的:比较胃癌患者术前行双能CT扫描的常规平扫及虚拟平扫图像,评估通过去除常规平扫来降低辐射剂量问题。方法:74例患者行胃双能CT扫描,测量病灶在虚拟平扫和常规平扫图像中的平均CT值、大小、图像质量和有效放射剂量,并进行比较。结果:在常规和虚拟平扫图像中胃癌的最大厚度和肿大淋巴结的最大直径均无显著意义(P>0.05)。在两者图像中所测组织的平均CT值除主动脉外具有显著差异(P<0.05),但绝对值差异值在10HU以下。在动脉期和门脉期的虚拟平扫图像中除主动脉外其他测量的组织CT值无统计学差异(P>0.05)。虚拟平扫图像的噪声较常规平扫图像低(P<0.01)。虚拟平扫图像可以对疾病进行诊断,但是图像质量较常规平扫低(P<0.01)。省去常规平扫所降低的放射剂量是21.40%±4.44%。结论:虚拟平扫在胃癌术前分期扫描中具有代替常规平扫的潜在应用价值,并能因此降低辐射剂量。
OBJECTIVE: To compare conventional and dual-function CT images of gastric cancer patients with preoperative biopsy and virtual plain scan images, and evaluate the reduction of radiation dose by removing conventional plain scan. Methods: Totally 74 patients underwent gastric dual-energy computed tomography (CT) scan. The mean CT value, size, image quality and effective radiation dose of the virtual lesion were compared and compared. Results: There was no significant difference between the maximum thickness of gastric cancer and the maximum diameter of enlarged lymph nodes in both conventional and virtual images (P> 0.05). The average CT value of the measured tissue in both images was significantly different (P <0.05) except for the aorta, but the absolute value of the difference was below 10HU. There was no significant difference in CT value between the aorta and portal venous phantom except the aorta (P> 0.05). The noise of virtual plain images was lower than that of conventional plain images (P <0.01). The virtual scan image can diagnose the disease, but the image quality is lower than the conventional scan (P <0.01). The reduction of radiotherapy dose saved by conventional plain scan was 21.40% ± 4.44%. Conclusion: The virtual scan in gastric cancer preoperative staging scan instead of the potential value of conventional scanning, and can thus reduce the radiation dose.