A Study of Fixed Current and Automatic Tube Current Modulation at a Fixed Low Tube Voltage in Low-dose Computed Tomography (CT) Imaging of Infant Lungs

Background: With the development of computed tomography (CT) technology, the number of infants undergoing CT examination has increased. Recently, problems associated with radiation exposure have attracted the public attention, and low-dose CT examination has become the research focus. Objectives: This study aimed to explore the feasibility of a fixed ultralow tube current combined with iDose(4) iterative reconstruction at a low tube voltage (80 kV) in low-dose CT scanning of infant lungs. Patients and Methods: Ninety infants, aged 0 - 3 years, undergoing enhanced chest CT scan (including plain CT scan and arterial scan), were included in the experimental group. In the experimental group, plain CT scan was performed at 80 kV under a fixed tube current (30 mA), and arterial phase CT scan was carried out at 80 kV with automatic tube current modulation (30 - 150 mA). Meanwhile, 90 infants, aged 0 - 3 years, undergoing non-enhanced chest CT scan, were randomly recruited as the control group. For the control group, plain CT scan was performed at 80 kV with automatic tube current modulation (30-150 mA). In each examination, the iDose4 iterative reconstruction technique was used for reconstruction. The volume CT dose index (CTDIvol), dose-length product (DLP), effective dose (ED, measured using a 32-cm diameter phantom), signal-to-noise ratio (SNR), and overall subjective quality of plain CT scans were analyzed and compared between the experimental and control groups. Results: Regarding the radiation dose in different age groups, the ED (mSv) was significantly lower in the experimental group compared to the control group (0-1-year-old subgroup: 0.48 +/- 0.05 mSv in the experimental group vs. 0.91 +/- 0.19 mSv in the control group, P < 0.05; 1-2-year-old subgroup: 0.50 +/- 0.01 mSv in the experimental group vs. 0.75 +/- 0.10 mSv in the control group, P < 0.05; and 2-3-year-old subgroup: 0.46 +/- 0.05 mSv in the experimental group vs. 0.79 +/- 0.11 mSv in the control group, P < 0.05). The image SNR was higher in the control group compared to the experimental group (P < 0.05), while the difference in subjective image quality was not significant between the experimental and control groups (P < 0.05). Conclusion: The chest CT examination of infants, aged 0 - 3 years, at a low tube voltage (80 kV) and a fixed tube current (30 mA), combined with the iDose4 iterative reconstruction technique, and the obtained images met the diagnostic criteria...