Value of reduction voltage based on body mass combined with automatic tube current technology in reducing chest CT radiation dose in children
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摘要:
目的 探讨基于体质量调节管电压联合自动管电流技术在降低儿童胸部CT辐射剂量中的可行性。 方法 选择2019年9~12月在联勤保障部队第九八九医院行胸部CT扫描的54例患儿胸部CT图像作为对照组,扫描参数:管电压100 kV或120 kV,管电流采用固定值,范围120~200 mA;另选择2020年1~5月行低剂量扫描的56例患儿胸部图像作为低剂量组,扫描参数:根据患儿体质量选择不同管电压,≤15 kg选择80 kV,≤40 kg选择100 kV, > 40 kg选择120 kV;管电流为自动管电流调节,比较两组患儿的辐射剂量和图像质量。 结果 对照组患儿胸部CT有效剂量为0.95±0.55 mSv,低剂量组患儿胸部CT有效剂量为0.18±0.17 mSv,辐射剂量仅为对照组的18.9%。对照组和低剂量组图像满足诊断标准的占比分别为98.15%和96.43%,两组差异无统计学意义(P=0.579)。 结论 在可满足诊断要求的前提下,根据患儿体质量选择不同管电压联合运用自动调节管电流技术可以有效降低胸部CT辐射剂量。 Abstract:Objective To explore the feasibility of reducing chest CT radiation dose by adjusting tube voltage based on body mass combined with automatic tube current technology in children. Methods The chest CT images of 54 children who underwent chest CT scanning in our hospital from September to December 2019 were collected as the control group. Scanning parameters: Tube voltage: 100 kV or 120 kV, tube current using fixed value: range from 120-200 mA. The chest images of 56 children who underwent low-dose scanning from January to May 2020 were collected as the low dose group. The scanning parameters were as follows: Different tube voltages were selected according to their body mass, 80 kV for body mass ≤15 kg, 100 kV for body mass ≤40 kg, 120 kV for body mass ≥40 kg, and the tube current was automatically adjusted. The radiation dose and image quality of the two groups were compared. Results The average effective dose of chest CT in control group was 0.95±0.55 mSv, and the average effective dose of chest CT in low dose group was 0.18±0.17 mSv, the radiation dose was only 18.9% of that in the control group. The proportion of images meeting the diagnostic criteria in control group and low dose group were 98.15% and 96.43%, respectively(P=0.579). Conclusion On the premise of meeting the diagnostic requirements, choosing different tube voltages according to the body mass of children combined with automatic regulation of tube current technology can significantly reduce the radiation dose of chest CT. -
Key words:
- body mass /
- radiation dose /
- low dose scanning /
- CT /
- tube voltage /
- tube current
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图 1 2位患儿胸部CT图像
Figure 1. Chest CT images of two children. A: The child was 5 years old, the scanning parameter was 120 kV and 200 mA, the image quality score was 4, DLP: 233.08, ED: 1.31 mSv; B: The child was 5 years old, the scanning parameter was 100 kV, and the image quality score was 4, DLP: 27.82, ED: 0.16 mSv. In both images, the lung texture was clear, and the pneumonia lesion was obvious, which meet the diagnostic criteria.
表 1 两组图像主观评估符合诊断标准率比较
Table 1. Comparison of subjective evaluation in accordance with diagnostic criteria between two groups of images
Group Qualified number (n) Ratio (%) Control group (n=54) 53 98.15 Low dose group (n=56) 54 96.43 χ2 0.3064 P 0.58 表 2 两组图像客观质量比较
Table 2. Comparison of objective quality between two groups of images (Mean±SD)
Group Signal-to-noise ratio Contrast-to-noise ratio Control group (n=54) 7.15±2.26 1.47±2.03 Low dose group (n=56) 5.31±0.82 1.34±0.85 t 3.73 0.29 P < 0.001 0.77 表 3 两组患儿辐射剂量比较
Table 3. Comparison of radiation exposure between two groups of children (Mean±SD).
Group DLP ED(mSv) Control group (n=54) 169.1±98.84 0.95±0.55 Low dose group (n=56) 31.54±31.28 0.18±0.17 U 170 167 P < 0.001 < 0.001 DLP: Dose length product; ED: Effective dose. -
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