Institut de Radiologie de Sion, Groupe 3R, Sion, Switzerland.
GE Healthcare, Buc, France.
Eur Radiol. 2019 Dec;29(12):6794-6804. doi: 10.1007/s00330-019-06257-x. Epub 2019 May 29.
To compare institutional dose levels based on clinical indication and BMI class to anatomy-based national DRLs (NDRLs) in chest and abdomen CT examinations and to assess local clinical diagnostic reference levels (LCDRLs).
From February 2017 to June 2018, after protocol optimization according to clinical indication and body mass index (BMI) class (< 25; ≥ 25), 5310 abdomen and 1058 chest CT series were collected from 5 CT scanners in a Swiss multicenter group. Clinical indication-based institutional dose levels were compared to the Swiss anatomy-based NDRLs. Statistical significance was assessed (p < 0.05). LCDRLs were calculated as the third quartile of the median dose values for each CT scanner.
For chest examinations, dose metrics based on clinical indication were always below P75 NDRL for CTDI (range 3.9-6.4 vs. 7.0 mGy) and DLP (164.0-211.2 vs. 250 mGycm) in all BMI classes except for DLP in BMI ≥ 25 (248.8-255.4 vs. 250.0 mGycm). For abdomen examinations, they were significantly lower or not different than P50 NDRLs for all BMI classes (3.8-9.0 vs. 10.0 mGy and 192.9-446.8 vs. 470mGycm). The estimated LCDRLs show a drop in CTDI (21% for chest and 32% for abdomen, on average) with respect to current DRLs. When considering BMI stratification, the largest LCDRL difference within the same clinical indication is for renal tumor (4.6 mGy for BMI < 25 vs. 10.0 mGy for BMI ≥ 25; - 117%).
The results suggest the necessity of estimating clinical indication-based DRLs, especially for abdomen examinations. Stratifying per BMI class allows further optimization of the CT doses.
• Our data show that clinical indication-based DRLs might be more appropriate than anatomy-based DRLs and might help in reducing large variations in dose levels for the same type of examinations. • Stratifying the data per patient-size subgroups (non-overweight, overweight) allows a better optimization of CT doses and therefore the possibility to set LCDRLs based on BMI class. • Institutions who are fostering continuous dose optimization and LDRLs should consider defining protocols based on clinical indication and BMI group, to achieve ALARA.
比较基于临床指征和 BMI 类别与胸部和腹部 CT 检查的基于解剖的全国 DRL（NDRL）的机构剂量水平，并评估当地临床诊断参考水平（LCDRL）。
2017 年 2 月至 2018 年 6 月，根据临床指征和体重指数（BMI）类别（<25；≥25）优化方案后，瑞士多中心组从 5 台 CT 扫描仪中收集了 5310 例腹部和 1058 例胸部 CT 系列。将基于临床指征的机构剂量水平与瑞士解剖学 NDRL 进行比较。评估了统计学意义（p<0.05）。LCDRL 计算为每个 CT 扫描仪中位数剂量值的第三个四分位数。
对于胸部检查，基于临床指征的剂量指标在所有 BMI 类别中均低于 P75 NDRL 的 CTDI（范围 3.9-6.4 与 7.0 mGy）和 DLP（164.0-211.2 与 250 mGycm），除了 BMI≥25 中的 DLP（248.8-255.4 与 250.0 mGycm）。对于腹部检查，除了 BMI≥25 中的 DLP（248.8-255.4 与 250.0 mGycm）外，在所有 BMI 类别中，它们均明显低于或与 P50 NDRL 无差异（3.8-9.0 与 10.0 mGy 和 192.9-446.8 与 470mGycm）。估计的 LCDRL 显示 CTDI 下降（胸部平均下降 21%，腹部平均下降 32%），与当前的 DRL 相比。当考虑 BMI 分层时，同一临床指征内最大的 LCDRL 差异是肾肿瘤（BMI<25 的 4.6 mGy 与 BMI≥25 的 10.0 mGy；-117%）。
结果表明，特别是对于腹部检查，有必要估计基于临床指征的 DRL。按 BMI 类别分层可进一步优化 CT 剂量。
• 我们的数据表明，基于临床指征的 DRL 可能比基于解剖学的 DRL 更合适，并可能有助于减少同一类型检查的剂量水平的较大差异。
• 根据患者体型亚组（非超重、超重）对数据进行分层，可更好地优化 CT 剂量，从而有可能根据 BMI 类别设置 LCDRL。
• 正在促进连续剂量优化和 LDRL 的机构应考虑基于临床指征和 BMI 组定义方案，以实现 ALARA。
