| [PURPOSE]:To assess the feasibility, fidelity applicability of adding noise on raw data for simulation of low dose CT scan of chest and to validate the result of low-dose CTPA in clinical PE cases. [METHODS]:Three sets of raw data were studied, including conventional chest CT scan of ten patients, CTPA CT scan of thirty patients,thin-section high resolution CT scan of ten patients, conventional CT scan of lung nodule mannequin and CTPA CT scan of thirty patients, Noise was added to simulate conventional CT scan with tube current of 60 mA and 30 mA, thin-section high resolution CT scan with tube current of 160 mA and 80 mA, For CTPA and mannequin data and CTPA, a series of noise were added to simulate tube current from 270 mA to 10 mA with interval of 10 mA and tube current of 100mA,60mA and 30mA.Noise index (NI) on levels of aortic arch and liver was measured and compared by paired t test and Pearson correlation analysis and statistic analyse.[RESULTS]: NI was different between scan data and simulated data of mannequin (P＜0.05), which had linear correlation (r=0.94-0.98); For conventional CT scan, NI was different on liver level (P＜0.05, r=0.82-0.93), while not different on aortic arch level, there had linear correlation; For high resolution CT scan, NI was different on both levels (P＜0.05, r=0.40-0.97),which had linear correlation too. For CTPA scan, NI was different between scan data and simulated data, which had linear correlation (r=0.831-0.967), the bulk of interobserver and intraobserver agreement (Kappa value) arrived at middling agreemeng (Kappa value=0.4). statistic difference appeared between uncertain result and positive result, but it did not related with tube current level. [CONCLUSION]:The noise between scan data and simulated data is comparable, and adding noise can be used for conventional CT low dose study and also can be used for CTPA:100mA tube current level could be used conventional sets of CTPA examination,60mA tube current level could be used countercheck sets. |
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