Evaluation of Radiation dose in Multislice Spiral CT for Pediatric Head

Objective To compare the radiation exposure delivered by low dose with standarddose multislice spiral CT (MSCT) in examination of pediatric head, and provide optimal CT scan parameters for pediatric head.Materials and Methods (1)120 volunteers were randomly assigned to undergo low dose or standard dose MSCT, 120 kVp, 90 mAs (n=30) scan for those at age less than 6 months, 150 mAs (n=30) scans for those at age from 6 months to 6 years, and 260 mAs (n=60) scans for both groups. The other scanning parameters were 0.75s, 1.5mm collimation, and 11.7 mm feed/rotation. Weighted CT dose index (CTDIw), dose length product (DLP), Effective mAs (eff.mAs) and total mAs produced by the every scanning protocol were compared. (2)CT images were evaluated by three doctors using blind method, and 3 degrees including normal image, image with few artifact, and image with excessive artifact, were employed and analyzed statistically.Results (1)CTDIw was 17.28 mGy for 90 mAs (34.6%), 28.85 mGy for 150 mAs (57.8%). DLP (237 mGycm for 90 mAs, 423 mGycm for 150 mAs scanning) of low-dose CT was lower than that (683 mGycm, 731 mGycm) of standard dose CT (all P0.01). (2)98% low dose image was fully readable, which was no significant difference (P0.05) with standard dose image.Conclusion Standard dose CT can be replaced by low-dose MSCT for examining pediatric head, radiation dose in pediatric head produced by low-dose CT was 35% or 57% of that produced by standard dose MSCT.