Pilot study of radiation dose reduction for pediatric head CT in evaluation of ventricular size.

BACKGROUND AND PURPOSE CT is a ubiquitous, efficient, and cost-effective method to evaluate pediatric ventricular size, particularly in patients with CSF shunt diversion who often need emergent imaging. We therefore sought to determine the minimum dose output or CT dose index required to produce clinically acceptable examinations. MATERIALS AND METHODS Using a validated noise insertion method and CT projection data from 22 patients, standard pediatric head CT images were reconstructed with weighted filtered back-projection and sinogram-affirmed iterative reconstruction corresponding to routine, 25%, and 10% dose. Reconstructed images were then evaluated by 3 neuroradiologists (blinded to dose and reconstruction method) for ventricular size, diagnostic confidence, image quality, evidence of hemorrhage, and shunt tip location, and compared with the reference standard. RESULTS There was no significant difference in the ventricular size ranking, and the sensitivity for moderate to severe hydrocephalus was 100%. There was no significant difference between the full-dose level and the ventricular size rankings at the 25% or the 10% dose level for either reconstruction kernel (P > .979). Diagnostic confidence was maintained across doses and kernel. Hemorrhage was more difficult to identify as image quality degraded as dose decreased but was still seen in a majority of cases. Shunts were identified by all readers across all doses and reconstruction methods. CONCLUSIONS CT images having dose reductions of 90% relative to routine head CT examinations provide acceptable image quality to address the specific clinical task of evaluating ventricular size.