Background

The size-specific dose estimate (SSDE) is a dose-related metrics that incorporates patient size into its calculation. It is usually derived from the volume computed tomography dose index (CTDI_vol) by applying a conversion factor determined from manually measured anteroposterior and lateral skin-to-skin patient diameters at the midslice level on computed tomography (CT) localiser images, an awkward, time-consuming, and not highly reproducible technique. The objective of this study was to evaluate the potential for the use of body mass index (BMI) as a size-related metrics alternative to the midslice effective diameter (D_E) to obtain a size-specific dose (SSDE) in abdominal CT.

Methods

In this retrospective study of patients who underwent abdominal CT for the investigation of inflammatory bowel disease, the D_E was measured on the midslice level on CT-localiser images of each patient. This was correlated with patient BMI and the linear regression equation relating the quantities was calculated. The ratio between the internal and the external abdominal diameters (D_RATIO) was also measured to assess correlation with radiation dose. Pearson correlation analysis and linear regression models were used.

Results

There was good correlation between D_E and patient BMI (r = 0.88). An equation allowing calculation of D_E from BMI was calculated by linear regression analysis as follows: D_E = 0.76 (BMI) + 9.4. A weak correlation between radiation dose and D_RATIO was demonstrated (r = 0.45).

Conclusions

Patient BMI can be used to accurately estimate D_E, obviating the need to measure anteroposterior and lateral diameters in order to calculate a SSDE for abdominal CT.

中文翻译：

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在腹部计算机断层扫描中使用体重指数来估计患者的个体放射剂量。

背景

特定于剂量的剂量估计（SSDE）是与剂量相关的指标，将患者的体重纳入其计算。它通常是根据体积计算机断层摄影剂量指数（CTDI _vol）通过应用转换系数得出的，该转换系数是根据在计算机断层摄影（CT）定位器图像上处于中片水平的手动测量的前后和外侧皮肤对皮肤的患者直径确定的，耗时且无法高度重复的技术。这项研究的目的是评估在腹部CT中使用体重指数（BMI）作为替代中片有效直径（D _E）的大小相关指标的潜力，以获取特定大小的剂量（SSDE）。

方法

在这项针对接受腹部CT检查以调查炎症性肠病的患者的回顾性研究中，在每位患者的CT定位器图像上的中片水平上测量了D _E。这与患者的BMI相关，并计算了与数量相关的线性回归方程。还测量内腹和外腹直径之间的比率（D _RATIO）以评估与放射剂量的相关性。使用Pearson相关分析和线性回归模型。

结果

D _E与患者的BMI之间存在良好的相关性（r  = 0.88）。通过线性回归分析如下计算允许从BMI计算D _E的方程：D _E  = 0.76（BMI）+ 9.4。辐射剂量和D _RATIO之间存在弱相关性（r  = 0.45）。

结论

患者的BMI可用于准确估计D _E，而无需测量前后和侧向直径，从而无需计算腹部CT的SSDE。