Value of CareDose 4D Technique in Skull CT Exam

Purpose: To investigate the value of CareDose 4D technique in decreasing radiation dose of multi-slice spiral CT in adult skull scanning. Methods: One hundred patients undergone skull CT were equally divided into group A and group B randomly. Routine protocol(130kV and 280mAs) was used in group A, and CareDose 4D technique was used in group B(quality reference mAs 240). Effective mAs value, volume CT dose index( CTDIvol) and dose length product(DLP) were recorded and signal to noise ratio(SNR) of the CT images were calculated after exam. The image quality at the top, suprasella cistern and base level of the skull was judged and classified as three levels( excellent,good,poor) by two deputy chief physicians with double blind method. Results: The mean CTDIvol and mean DLP for group A was 61.94 mGy and 669 mGy·cm, those for group B was 43.32 mGy and 467.88 mGy·cm, the differences of CTDIvol and DLP between these two groups were with statistical significance(P0.001). The SNR of images in group B was lower than that in group A, at top level of the skull, the difference was with no statistical significance(P0.05), but at the suprasella cistern and base level, the difference was with statistical significance(P0.05). For the image quality evaluation,the average fine rate was 97.3% in group A,and 94.6% in group B. There was no statistical significant difference between them(P0.05). Conclusion: CareDose 4D technique provides a regulated mAs real-time on line,it not only raises utilization rate of radiation and decreases radiation dose,but also promises the image quality in skull CT scanning,and has some clinical significance.