Systematic Review and Meta-Analysis of Radiation Dose Reduction Studies in Pediatric Head CT

BACKGROUND: Conventional imaging protocols used in pediatric head CT scanning without specific adaptations to lower radiation dose or “standard dose” pediatric head CTs increase unnecessary radiation exposure. Modifying CT parameters, utilizing iterative reconstruction, and adopting specialized protocols are ongoing strategies to lower radiation dose in pediatric head CTs.

PURPOSE: This article reviews studies reducing radiation exposure in pediatric patients undergoing head CT and provides meta-analysis of percent radiation dose reduction of the studies.

DATA SOURCES: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we utilized EMBASE, Ovid MEDLINE, Scopus, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, and Clinicaltrials.gov to identify all relevant articles pertaining to radiation dose reduction in pediatric head CT.

STUDY SELECTION: All human studies (excluding animal, phantom, and cadaveric) published after 2012 aiming to lower radiation dose of a “routine” or “standard” dose CT protocol in use were selected for review.

DATA ANALYSIS: We extracted study characteristics such as location, sample size, scanner, clinical indication, CT protocol parameter modifications, iterative reconstruction method if applicable, dose reduction, image quality metrics, and overall findings. CT protocol parameter modifications and dose reduction were summarized by using descriptive statistics. Meta-analyses on percent dose reduction were performed. Meta-analyses were subgrouped by clinical indication, use of iterative reconstruction, and age group to isolate sources of heterogeneity between studies. Limitations included heterogeneity of study protocols, incomplete protocol/outcome reporting, and variability of institution, scanner, patient demographics. Clinical indication limits the generalizability of our findings.

DATA SYNTHESIS: This review identified 20 studies modifying their routine or standard dose pediatric head CT protocols on human patients. These studies modified CT parameters with or without the use of iterative reconstruction and/or used specialized protocols. Most common CT parameters modifications consisted of decreasing tube current time product (mAs) (n = 13) and/or tube voltage (kV) (n = 9). The most successful dose reduction studies had the clinical indication of craniosynostosis and utilized iterative reconstruction. Ernst and colleagues (2016) utilized model-based iterative reconstruction for craniosynostosis and reduced effective dose by 97% and Lyoo and colleagues (2023) utilized advanced modeled iterative reconstruction with ClariCT for craniosynostosis and reduced CT dose index volume by 95.9%. Meta-analyses revealed significant differences in percent dose reduction based on clinical indication.

LIMITATIONS: Heterogeneity of study protocols, incomplete protocol/outcome reporting, and variability of institution, scanner, patient demographics, and clinical indication limit the generalizability of our findings.

CONCLUSIONS: This systematic review and meta-analysis identifies tube current time product as the most commonly modified CT parameter and also highlights CT clinical indication as an important factor to isolate when comparing dose reduction studies. Further research should further investigate iterative reconstruction techniques as well as photon-counting CT to maximize radiation dose reduction of pediatric head CT.