[1]梁保辉,付亚军,曹明娜.基于CT检查的正位定位像计算等效水直径[J].南方医科大学学报,2020,(06):799-805.[doi:10.12122/j.issn.1673-4254.2020.06.05]
 Calculation of water equivalent diameter based on anteroposterior localizer CT images[J].Journal of Southern Medical University,2020,(06):799-805.[doi:10.12122/j.issn.1673-4254.2020.06.05]
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基于CT检查的正位定位像计算等效水直径()
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《南方医科大学学报》[ISSN:1673-4254/CN:44-1627/R]

卷:
期数:
2020年06期
页码:
799-805
栏目:
出版日期:
2020-06-17

文章信息/Info

Title:
Calculation of water equivalent diameter based on anteroposterior localizer CT images
作者:
梁保辉付亚军曹明娜
关键词:
计算机断层成像体型特异性辐射剂量定位像等效水直径
Keywords:
computed tomography size specific dose estimates localizer radiograph water equivalent
DOI:
10.12122/j.issn.1673-4254.2020.06.05
文献标志码:
A
摘要:
目的 研究基于CT检查的正位定位像计算等效水直径(Dw)的方法,用于计算CT检查的体型特异性辐射剂量(SSDE)。方法 利用GE Revolution CT和LightSpeed VCT设备,设置管电压为80、100、120 kV分别扫描直径为16 cm和32 cm圆柱形CT剂量体模,获取正位定位像和断层图像。根据断层图像的CT值的定义获得体模材料相对于水的衰减系数,用于计算剂量体模的体模厚度转换为等效水厚度,再对定位像的灰度值与等效水厚度进行线性拟合获得刻度曲线。利用CT剂量体模和22例胸腹部检查数据验证基于定位像计算Dw的方法。结果 基于定位像和断层图像计算CT剂量体模Dw的偏差小于3%。两种方法计算未成年人胸腹部CT检查的Dw变化趋势一致,计算胸腹部CT检查中间层面的Dw和所有断层Dw均值的偏差分别小于6.6%和7.5%。结论 利用CT正位定位像和断层图像刻度定位像的灰度值与等效水厚度,建立基于定位像计算Dw的方法,可用于快速 计算SSDE。
Abstract:
Objective To explore a method for calculating water equivalent diameter (Dw) based on localizer CT images for calculation of the size specific dose estimates (SSDE). Method GE Revolution CT and LightSpeed VCT were used to scan CT dose index phantoms 16 cm and 32 cm in diameter at the tube voltages of 80, 100 and 120 kV to obtain the axial image and anteroposterior localizer radiograph. According to the definition of CT Hounsfield unit, the axial images were used to calculate the conversion factors that convert the phantom thickness to water equivalent thickness. The gray value of the localizer radiograph and the water equivalent thickness were calibrated with a linear equation, and the parameters of the calibration were used to calculate the water equivalent thickness. The method was verified using 2 CT dose index phantoms and in 22 patients undergoing chest and abdominal CT examination. Result Comparison of the water equivalent diameter (Dw) based on the localizer radiograph and axial image of the 2 phantoms showed that the percentage difference between Dw from the axial images and from the localizer radiograph was below 3% . The trend of Dw variations with location in the two methods was sonsistent. The difference in Dw in intermediate region of interest between the axial image and the localizer radiograph from the 22 patients was below 6.6% . With the mean Dw in the ROI, the maximum percentage difference was 7.5% . Conclusion Calibration of the gray value of the localizer radiograph and the water equivalent thickness using the axial image and localizer radiograph of CT dose index phantoms allows quick calculation of the SSDE based on the parameters of calibration.
更新日期/Last Update: 2020-06-17