Abstract

BackgroundModern CT scanners provide automatic dose adjustment systems, which are promising options for reducing radiation dose in pediatric CT scans. Their impact on patient dose, however, has not been investigated sufficiently thus far.ObjectiveTo evaluate automated tube voltage selection (ATVS) in combination with automated tube current modulation (ATCM) in non-contrast pediatric chest CT, with regard to the diagnostic image quality.Materials and methodsThere were 160 non-contrast pediatric chest CT scans (8.7±5.4 years) analyzed retrospectively without and with ATVS. Correlations of volume CT Dose Index (CTDIvol) and effective diameter, with and without ATVS, were compared using Fisher’s z-transformation. Image quality was assessed by mean signal-difference-to-noise ratios (SDNR) in the aorta and in the left main bronchus using the independent samples t-test. Two pediatric radiologists and a general radiologist rated overall subjective Image quality. Readers’ agreement was assessed using weighted kappa coefficients. A p value <0.05 was considered significant.ResultsCTDIvol correlation with the effective diameter was r = 0.62 without and r = 0.80 with ATVS (CI: -0.04 to -0.60; p = 0.025). Mean SDNR was 10.88 without and 10.03 with ATVS (p = 0.0089). Readers’ agreement improved with ATVS (weighted kappa between pediatric radiologists from 0.1 (0.03–0.16) to 0.27 (0.09–0.45) with ATVS; between general and each pediatric radiologist from 0.1 (0.06–0.14) to 0.12 (0.05–0.20), and from 0.22 (0.11–0.34) to 0.36 (0.24–0.49)).ConclusionATVS, combined with ATCM, results in a radiation dose reduction for pediatric non-contrast chest CT without a loss of diagnostic image quality and prevents errors in manual tube voltage setting, and thus protecting larger children against an unnecessarily high radiation exposure.

Highlights

  • Possible ionizing radiation effects in the young and growing bodies of children [1, 2] require that radiation exposure and scan protocols must be carefully adapted to size, age, and clinical needs [3,4,5,6,7]

  • CareDose4D assesses the cross-sectional size of the patient being scanned and adjusts tube current time product relative to the reference tube current time product, which is set by the user for the selected examination and for an average-sized patient (70–80 kg for adults, 20kg for children), to provide adequate image noise [8]

  • In the automated tube current modulation (ATCM) group, there were two acquisition protocols with two different tube voltages (80 kV and 100 kV), depending on the patient weight, and radiographers in our hospital tended to manually increase kV to adjust for higher patient weights without adjusting reference mAs for the tube current modulation which resulted in unnecessarily high radiation doses for some larger children

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Summary

Introduction

Possible ionizing radiation effects in the young and growing bodies of children [1, 2] require that radiation exposure and scan protocols must be carefully adapted to size, age, and clinical needs [3,4,5,6,7]. Modern CT scanners provide automatic dose adjustment systems, such as automated tube current modulation (ATCM) [8,9,10,11] and automated tube voltage selection (ATVS) [12,13,14,15,16,17,18,19]. Modern CT scanners provide automatic dose adjustment systems, which are promising options for reducing radiation dose in pediatric CT scans. Their impact on patient dose, has not been investigated sufficiently far

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