Chest High-Resolution Computed Tomography for chronic suppurative lung disease in late childhood and early adolescence: Radiation dose and image quality evaluation using iDose4 Iterative Reconstruction Algorithm

Abstract

Purpose: The large number of computed tomography (CT) examinations taking place in everyday clinical practice has increased the risk for radiation-induced carcinogenesis, especially in children with longer life expectancy than adults. The recently developed Iterative Reconstruction (IR) algorithms reduce image noise and therefore radiation exposure. This study compares the iDose 4 IR Algorithm with Filtered-Back Projection (FBP) in terms of radiation exposure and image quality (IQ) in 31 chest high resolution CT (HRCT) examinations performed in school-aged children with chronic suppurative lung disease (7-13 years old, weighing >30 kgs). Material and Methods: Thirteen patients were scanned using the FBP protocol (FBP group) and 18 patients using the iDose 4 protocol (iDose group) and reduced tube current-time product (mAs). Both groups were scanned on a 64-detector row CT scanner. The iDose group images were reconstructed with iDose levels 2, 4 and 6. Radiation exposure was estimated, while subjective and objective IQ was evaluated. Unpaired t-test was used for data statistical analysis. Results: The iDose 4 application allowed a significant dose reduction (up to 64%). Subjective image noise was comparable between FBP and iDose 4 images, whereas objective image noise was comparable between FBP and iDose level 2 images. Oversmoothing artefacts already described in literature were only noticed in a few cases with iDose level 6, but without significantly affecting the diagnostic acceptability. Conclusions: The use of the iDose 4 IR algorithm in chest HRCT of preadolescent and early adolescent-aged children leads to significant dose reduction, without significantly affecting IQ. Further evaluation with a larger patient sample and lower mAs settings is needed in order to investigate further reduction of exposure parameters in chest HRCT of children weighing more than 30 kgs.