Predicting Exceedance of National Diagnostic Reference Levels for Two-view Chest Radiography in Germany based on...

Two-view chest X-ray (CXR) is a widely utilized diagnostic tool due to its accessibility, cost-effectiveness, and ability to evaluate thoracic pathologies. The current diagnostic reference levels (DRLs) in Germany for posterior-anterior (PA) and lateral CXR are 12.0 and 40.0 cGy × cm², respectively. This study assessed the dose contributions of PA and lateral CXR for different body mass index (BMI) groups, aiming to determine the best possible BMI thresholds to predict exceedance of the national DRLs.

In this retrospective study, 3,982 patients underwent a total of 4,958 two-view chest radiograms using a twin robotic X-ray system. Dose-area products (DAP) of each BMI group were compared between projections using Wilcoxon signed rank tests. Receiver operating characteristic statistics were employed to identify BMI values likely to result in doses above the DRLs.

For each BMI group, lateral CXR resulted in higher DAP than PA radiograms (all p<0.001). The smallest median DAP difference was found for underweight patients (BMI <18.5 kg/m²; 12.2 versus 4.8 cGy × cm²; 154.2% higher DAP in lateral CXR), whereas the largest difference was observed among severely obese individuals (>40.0 kg/m²; 142.1 versus 21.7 cGy × cm²; 554.8%). The correlation of BMI and DAP was strong for both lateral and PA CXR (r = 0.614 and 0.641, both p<0.001). The best possible BMI thresholds to predict DRL exceedance were determined to be 26.5 kg/m² for lateral CXR (72.6% sensitivity / 76.1% specificity) and 27.8 kg/m² for PA radiograms (78.1% / 74.4%).

BMI information facilitates prediction of DRL exceedance. The findings presented may serve as a basis for future discussions on whether BMI-dependent reference levels could help to optimize dose management in chest imaging.

· Lateral views contribute the majority of radiation dose in two-view CXR.. · Patient BMI correlates strongly with dose exposure.. · Recording patient height and weight information is helpful for radiation dose management..

· Huflage H, Razinskas G, Weick S et al. Predicting Exceedance of the National Diagnostic Reference Levels for Two-view Chest Radiography in Germany based on Patients' Body Mass Index. Rofo 2026; DOI 10.1055/a-2810-5285.