A Comprarative Study Of Radiation Dose And Image Quality Between Spectral Imaging And Conventional CT In Thorax

Objective:To explore the possibility and clinical application of spectral imaging in Chest Scan by comparing the radiation dose and image quality between spectral imaging and conventional CT.Materials and methods:33 patients suspected with thorax disease which need unenhanced and enhanced chest scanning were included in this prospective study for a self controlled study. The chest scan sequence consisted conventional unenhanced CT, enhanced spectral image with both arterial and venous phase at the same scanning range and FOV. Proper spectral imaging model were selected to conduct arterial phase enhanced scan according to the conventional CT and adjusting mAs to get images of venous stage under spectral imaging. Both the enhanced spectral reconstructed images obtained at 70 keV. Each series'radiation dose parameters was got according to the phantom and image quality parameters through the GSI2.0 processing workstation of AW461. Taking the conventional CT chest scan as the self-control group, make a comparative analysis about the different series'radiation dose and quality parameters between conventional unenhanced CT and enhanced spectral image both in arterial and venous phase by t test, then explore the difference between them.Results:The mean CTDI of spectral scanning arterial phase and conventional CT were (10.3±0.0)mGy and (11.1±3.9)mGy respectively, dose-length product were (357.6±48.7) mGy and (380.6±136.0) mGy respectively. There is no significant difference between them (P> 0.05). The image qualities of conventional CT have no significant difference in comparison with spectral scanning at the selected 9 ROIs of 3 planes (P> 0.05). The mean CTDI and dose-length product were (15.8±5.7)mGy and (532.9±198.8)mGy · am respectively in spectral scanning of venous phase, which shows significant statistical difference between them (P<0.05), which means the conventional CT got lower mean CTDI and dose-length product than spectral scanning of venous phase. Meanwhile, 7 groups of 9 ROIs show significantly statistical difference in the image qualities (P<0.05) between conventional CT and the spectral scanning of venous phase, which means the spectral scanning of venous phase get better image quality than conventional CTConclusions:The gemstone spectral imaging has similar dose with conventional CT in chest scan when proper parameters were selected. The noise of single energy spectral image is lower than that of FBP reconstructed images at 70 keV, which implicates clinically applicability.