胸部CT扫描中颈部伸展体位应用价值的探讨

Evaluation of the value of neck extension in chest CT scanning

目的探讨在胸部CT扫描中患者颈部伸展使甲状腺腺体上移以减少甲状腺辐射暴露的可能性。方法对2017年3至6月北京朝阳医院进行胸部CT检查1994例患者的图像资料进行比较分析,按颈部体位不同分为伸展组和常规组,每组997例,伸展组患者头颈部后仰成颌顶位。常规组采用常规头颅扫描头架,头部正常体位。以第一肋骨头为基准计数标志,观察两组患者甲状腺腺体暴露于扫描范围内的腺体长度及腺体全部移出扫描范围的例数。比较两组患者原发射线区域内甲状腺腺体扫描长度的差别。结果伸展组患者甲状腺腺体暴露于扫描范围内的长度(4.69±5.68)mm,显著短于常规组(17.16±6.68)mm患者,差异有统计学意义(U=91073.5,P<0.05),并且伸展组患者甲状腺腺体完全脱离扫描范围内的例数519例,多于常规组32例,差异有统计学意义(U=594.8,P<0.05)。52.1%患者的甲状腺腺体完全脱离扫描范围内原发射线的辐射暴露。结论胸部CT扫描时患者颈部伸展可以使甲状腺腺体位于扫描野内的长度缩短,有效提高甲状腺的辐射防护。

Objective To explore the possibility that the neck extension in chest CT scanning would make thyroid move upward and reduce thyroid radiation exposure.Methods The images of 1994 patients who underwent chest CT examination in Beijing Chaoyang Hospital from March to June in 2017 were compared and analyzed retrospectively.According to different cervical positions,patients were divided into extension group and routine group with 997 cases in each group.In the extension group,the head and neck bended back to the maxillary top position while in the regular group with normal position.The length of thyroid glands exposed to the scanning range and the number of cases of all glands moved out of the scanning range were observed with the first rib head as the baseline counting mark.The differences in exposed length of thyroid gland in primary radiation area between the two groups were compared.Results The length of exposed thyroid gland by primary radiation in the extension group(4.69±5.68)mm was significantly shorter(U=91073.5,P<0.05)than that in the routine group(17.16±6.68)mm.In addition,the number of thyroid glands out of scanning range completely in the extension group(n=519,with ratio of 52.1%)was significantly more(U=594.8,P<0.05)than those in the routine group(n=32,with ratio of 3.2%).Conclusions During chest CT scan,the length of thyroid gland in the scanning field can be shortened with neck backbend position and the radioation protection for thyroid gland can be effectively improved.