Z-DOM技术结合iDose4在儿童上颈段椎体CT扫描中的应用价值

目的：探讨Z轴自动管电流调节（Z-DOM）技术结合第4代迭代重建（iDose4）在儿童上颈段椎体CT扫描中降低辐射剂量的应用价值。方法：选取儿童患者上颈段椎体CT扫描55例为实验组，使用Z-DOM技术结合iDose4进行低剂量扫描，另回顾性选取42例同部位常规剂量CT扫描的儿童患者为对照组。记录2组病例扫描时机器自动显示的容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP），计算有效剂量（ED），同时记录实验组每位患者扫描图像上的最小管电流（mAs）值和最大mAs值。每位患者均测量图像信号强度、图像噪声、背景噪声、计算图像信噪比（SNR）。结果：实验组最小mAs为（45±11），最大mAs为（61±14），对照组mAs均为250.0，实验组比对照组mAs最大下降234，平均下降205～189（75.6%～82.0%）；实验组CTDIvol为（3.7±1.1）mGy，对照组CTDIvol为16.9 mGy；实验组DLP为（28.3±9.0）mGy·cm，对照组DLP为（126.6±17.4）mGy·cm；实验组ED为（0.3±0.1）mSv，对照组ED为（1.4±0.2）mSv。2组最小mAs、最大mAs、CTDIvol、 DLP及ED比较差异均有统计学意义（P＜0.05）。实验组图像信号强度为（53.9±8.8），对照组为（57.2±5.8）；实验组图像噪声为（7.1±1.8），对照组为（4.1±1.1）；实验组图像背景噪声为（8.5±1.4），对照组为（3.9± 0.7）；实验组图像SNR为（8.1±2.1），对照组为（14.4±3.7）。2组图像信号强度、图像噪声、背景噪声及图像SNR比较差异均有统计学意义（P＜0.05），实验组图像信号强度和SNR比对照组低，图像噪声和背景噪声比对照组高。实验组中的28例CT复查、18例磁共振扫描和1例手术病例的诊断结果均与实验组扫描的诊断结果相一致。结论：儿童患者上颈段椎体CT检查使用Z-DOM技术结合iDose4进行实时在线调节mAs并有效降低噪声，既可以大幅度降低辐射剂量，又能保证图像质量。

Application value of Z-DOM technique combined with iDose4 in CT scan of the upper cervical vertebrae of children

Objective: To investigate the application value of Z-DOM technique combined with iDose4 in reducing radiation dose in CT scan of the upper cervical vertebrae in children. Methods: A total of 55 child patients experiencing upper cervical vertebrae CT scan were selected as the experimental group, in which Z-DOM technique combined with iDose4 was used for low-dose scanning. Meanwhile, another 42 child patients receiving routine-dose CT scanning of the same site were selected as control group (not using Z-DOM technique combined with iDose4, 250 mAs). During the scanning, Volume CT dose index (CTDIvol) and Dose length product (DLP) of the two groups automatically displayed in the machine were respectively recorded, and the effective dose (ED) were calculated. The minimum and maximum values of mAs on the scanned image of each patient in the experimental group were also recorded. The image signal intensity, image noise, and background noise of each case were measured, and the signal noise ratio (SNR) was calculated. Results: The minimum mAs value of the experimental group was (45±11), and the maximum was (61±14), while the mAs values in the controlgroup were all 250.0. Compared with the control group, the mAs values in the experimental group decreased by 234 mAs at maximum, with an average decline of 205 to 189 (75.6% to 82.0%). The CTDIvol, DLP, and ED of the experimental group were (3.7±1.1) mGy, (28.3±9.0) mGy•cm, and (0.3±0.1) mSv, respectively, while those in the control group were 169.0 mGy, (126.6±17.4) mGy•cm, and (1.4±0.2) mSv, respectively. The minimum mAs, the maximum mAs, the CTDIvol, the DLP and the ED were statistically different between the two groups. The intensity of the image signal, image noise, and background noise in the experimental group was (53.9±8.8), (7.1±1.8), and (8.5±1.4), respectively, while those in the control group were (57.2±5.8), (4.1±1.1), and (3.9±0.7), respectively. The SNR of the experimental group was (8.1±2.1) and that of the control group was (14.4±3.7). The intensity of image signal, image noise, background noise and SNR were statistically different between the experimental group and the control group. The image signal intensity and SNR of the experimental group were lower than those of the control group, while the image noise and background noise were higher. The diagnostic results of 28 cases of CT reexamination, 18 cases of MRI scans and 1 surgical case were consistent with those of the scan of the experimental group. Conclusion: With Z-DOM technology combined with iDose4, CT examination of the upper cervical vertebrae in children is of promising clinical appilcation value, as it enables real-time online adjustment of mAs and reduces the noise effectively, which cut down on radiation dose and ensures image quality.