Establishing paediatric diagnostic reference levels using reference curves - A feasibility study including conventional and CT examinations

Purpose: To derive Regional Diagnostic Reference Levels (RDRL) for paediatric conventional and CT examinations using weight-based DRL curves and compare the outcome with DRL derived using the weight groups.

Methods: Data from 1722 examinations performed at 29 hospitals in four countries were included. DRL was derived for four conventional x-ray (chest, abdomen, pelvis, hips/joints) and two types of CT examinations (thorax, abdomen). DRL curves were derived using an exponential fit to the data using weight as an independent variable and the respective radiation dose indices (P_KA, CTDI_vol, DLP) as dependent variables. DRL was also derived for weight groups for comparison. The result was compared with national diagnostic reference level (NDRL) curves.

Results: The derived curves show similarities with the NDRL curves available and corresponded sufficiently well with DRL for weight groups using the same data set, if sufficient number of data was available.

Conclusions: We conclude that weight-based DRL curves are a feasible approach and could be used together with DRL for weight groups. The main advantage of DRL curves is its application in the clinic. When the examination frequency is low, time to collect enough data to establish typical values for one or several weight groups may be unreasonably long. The curve provides the means to compare dose level faster and with fewer data points.