Local clinical diagnostic reference levels for chest and abdomen CT examinations in adults as a function of body mass index and clinical indication: a prospective multicenter study
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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 CTDIvol (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 CTDIvol (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.
KeywordsMultidetector computed tomography Radiometry Health care Clinical protocols
Body mass index
Clinical diagnostic reference level
Channelized Hotelling observer
Computed tomography dose index
Dose length product
Diagnostic reference level
European study on clinical DRLs
International Commission on Radiological Protection
Local clinical diagnostic reference level
Local diagnostic reference level
Multidetector CT scanner
National diagnostic reference level
The authors would like to thank Christophe Dias, Camille La Fay, Hugo Pasquier, and Dr Michael Seidenbusch for their valuable contribution to this article.
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Dominique Fournier.
Conflict of interest
The authors of this manuscript declare relationships with the following companies:
Federica Zanca was a former employee of GE Healthcare.
Stephane Montandon is a Philips employee.
Statistics and biometry
No complex statistical methods were necessary for this paper.
A written informed consent is submitted to every patient upon admission in Groupe 3r stating, among others, possible use of anonymized patient data for research purposes. The patient is free to oppose this use and listed as such. Specific written informed consent was therefore waived by the Institutional Review Board.
Institutional Review Board approval was obtained.
• Multicenter study
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