Dual-Layer Detector Head CT to Maintain Image Quality While Reducing the Radiation Dose in Pediatric Patients

Abstract

BACKGROUND AND PURPOSE: Radiation exposure in the CT diagnostic imaging process is a conspicuous concern in pediatric patients. This study aimed to evaluate whether 60-keV virtual monoenergetic images of the pediatric cranium in dual-layer CT can reduce the radiation dose while maintaining image quality compared with conventional images. MATERIALS AND METHODS:One hundred six unenhanced pediatric head scans acquired by dual-layer CT were retrospectively assessed. The patients were assigned to 2 groups of 53 and scanned with 250 and 180 mAs, respectively. Dose-length product values were retrieved, and noise, SNR, and contrast-to-noise ratio were calculated for each case. Two radiologists blinded to the reconstruction technique used evaluated image quality on a 5-point Likert scale. Statistical assessment was performed with ANOVA and the Wilcoxon test, adjusted for multiple comparisons.RESULTS: Mean dose-length product values were 717.47 (SD, 41.52) mGyÂcm and 520.74 (SD, 42) mGyÂcm for the 250-and 180-mAs groups, respectively. Irrespective of the radiation dose, noise was significantly lower, SNR and contrast-to-noise ratio were significantly higher, and subjective analysis revealed significant superiority of 60-keV virtual monoenergetic images compared with conventional images (all P , .001). SNR, contrast-to-noise ratio, and subjective evaluation in 60-keV virtual monoenergetic images were not significantly different between the 2 scan groups (P . .05). Radiation dose parameters were significantly lower in the 180-mAs group compared with the 250-mAs group (P , .001).CONCLUSIONS: Dual-layer CT 60-keV virtual monoenergetic images allowed a radiation dose reduction of 28% without imagequality loss in pediatric cranial CT.ABBREVIATIONS: CNR ¼ contrast-to-noise ratio; CTDI vol ¼ volume CT dose index; DECT ¼ dual-energy CT; DLCT ¼ dual-layer CT; DLP ¼ dose-length product; GWMA ¼ assessment of GM-WM differentiation; PFAA ¼ assessment of artifacts in posterior fossa; SSA ¼ assessment of the subcalvarial space; SAI ¼ subcalvarial artifact index; VMI ¼ virtual monoenergetic image