| Objective To investigate the sensitivity in detection of pulmonary nodules in variable low doses, and to evaluate the imaging quality of low-dose CTby experimental research.Methods Three groups of different types of artificial nodules (10mm,5mm,3mm) were implanted in inflated pig lungs and then placed inside chest phantom. The phantom was scanned by spectrum CT at standard-dose (tube voltage:120kV, pitch:0.984:1, tube current:250mAs) and low-dose (tube voltage:120kV, pitch:0.984:1, tube current:50,30,20, and10mA) respectively. The radiation dose (CTDIw and DLP) from the different scanning methods were recorded, and the noise and artifact of the images and visibility of the nodules were assessed.Result The radiation dose at low-dose decreased to6.7-33.3percent of which scanning at standard-dose. There was no statistical difference of the Hu between standard-dose and low-dose (P>0.05), while the SD of which was of statistical signification (P<0.05). The linear artifact was shown only in the images of the groups of20mA and10mA. The groups of50mA had a good confidence with standard-dose(0.4≤kappa<0.75).On the images with20mA, the3rd segmental bronchi were well seen and the pulmonary nodules were all detected accurately, while the10mA scanning failed to detect some3mm nodules.Conclusion The radiation dose produced by low-dose spectrum CT scanning was markedly lower than that of conventional dose CT scanning. Although the image noise and artifact was significant in low-dose CT, the normal structures of the lungs and the lesions could be well shown.20mA was the optimized parameter in our system. |
