EuroSafe Imaging 2019
Action 2 - Clinical diagnostic reference levels (DRLs), Action 3 - Image quality assessment based on clinical indications, Action 6 - Clinical audit tool for imaging, Radioprotection / Radiation dose, Abdomen, Thorax, CT, Diagnostic procedure, Dosimetric comparison, Quality assurance
H. Brat, F. Zanca, B. Rizk, S. Montandon, D. Racine, D. Fournier
"Diagnostic reference level" (DRL): Definitions
- introduced in 1996 by the International Commission on Radiological Protection (ICRP) (1),
- updated in 2017 regarding recommendations on DRLs in medical imaging and clarification issues related to definitions of the terms (2).
According to ICRP publication 135 (2):
- National DRLs (NDRLs) are representative of an entire country,
- Local DRLs (LDRLs) are representative of a few healthcare facilities in a local area.
They consider faster local optimization processes than NDRLs and remain anatomy-based.
NDRLs and LDRLs are calculated as the third quartile of the median dose values of each CT modality.
- Clinical DRLs (CDRLs) define more specific dose levels according to the needed image quality for a specific clinical indication (example: a CT of the abdomen to exclude renal calculi will require a lower patient exposition than to characterize a kidney tumor),
- Local Clinical DRLs (LCDRLs) are representative of a few healthcare facilities in a local area for specific clinical indications.
LCDRLs are calculated as the third quartile of the median dose values of each CT scanner involved in a study.
- The European Society of Radiology (ESR) has recently started a European prospective study,
named EUCLID (European study on Clinical DRLs),
among EuroSafe Imaging Stars to develop a set of CDRLs based on clinical indication rather than anatomical location.
These CDRLs are intended to help reducing large variations in dose levels for the same type of examinations.
the American College of Radiology (ACR) tried to go one step further in the definition of DRLs by introducing patient size (3).
DRLs: Remaining Limitations
DRLs for adults have been confined to representative standard patient:
- the DRL is defined as the 75th percentile of the mean doses for a sample of patients close to the standard size,
typically 70 kg or,
in some countries,
larger fractions of patients are currently non-standard,
as it can be seen from the data presented in this study,
where overweight patients are not outliers,
but a large part of the population.
This multicenter prospective study aims at contributing to the definition of local clinical DRLs (LCDRLs) for chest and abdomen examinations in CT,
while considering influence of patient BMI and comparing them to the recently published updated Swiss DRLs (4).