Effect of reduction in tube current on reader confidence in paediatric computed tomography.

BACKGROUND: Computed tomography (CT) contributes significantly to the total radiation dose derived from medical imaging in children. As the number of CT examinations increases there is renewed interest in possible ways to minimize such radiation. AIM: To study the effect of decremental reduction in tube current settings on structural resolution and on reader confidence in being able to reach a final diagnosis. MATERIALS AND METHODS: The study involved spiral CT of children aged 0-13 years. CT performed at reduced mA settings (60-75, 76-90 and 91-130 mA for thoracic, abdominal and pelvic examinations, and 76-90 and 91-130 mA for cranial examinations) were compared with similar investigations at conventional settings (180-240 mA). Images were scored by two blinded readers for structural resolution and diagnostic confidence. Structural resolution was scored on a binary (adequate or not) scale for six structures each in cranial, thoracic and pelvic examinations and for eight structures in abdominal studies, and reader confidence was scored on a four-point scale as 25-100%. Scores from the two readers were averaged for comparison in subgroup analyses. RESULTS: Reduction of tube current settings to 75-90 mA for thoracic, abdominal and pelvic examinations and to 90-130 mA for cranial examinations was not associated with any significant deterioration in image quality. The number of scans considered satisfactory were comparable even at 60-75 mA, although the total relative scores for structural resolution at this setting were lower. CONCLUSION: Tube current settings can be significantly reduced in all paediatric age groups, in all regions. In younger children the impact of such reduction in tube current is likely to be greater. Cranial scans are more sensitive to such reductions as compared to thoracic or abdominopelvic examinations.

Duke Scholars

Author Madan Mohan Rehani Radiology