Application of chest low-dose CT screening of Corona Virus Disease 2019 with a third-generation dual-source scanner

Objective: To investigate the application value of third-generation dual-source CT (3-G DSCT) low-dose scan mode combined with iterative reconstruction technology in the screening of COVID-19 and to evaluate the radiation dose. Methods: One hundred and twenty patients suspected of COVID-19 from December 2019 to February 2020 were retrospectively analysed and randomly divided into two groups (test group and conventional group, 60 patients in each). The parameters for test group included 3-G DSCT, Turbo Flash scan mode, CARE kV, with reference 90 kV, pitch 2.0, and ADMIRE algorithm, while those parameters for conventional group included the 128-slice CT, conventional spiral scan mode, 120 kV, pitch 1.2, and FBP algorithm. The CT values of aorta, spinal posterior muscle, and subcutaneous fat, the aortic noise, signal-to-noise ratio (SNR), and contrast noise ratio (CNR) were compared to evaluate the image quality between two groups. Two experienced doctors scored the image quality using a double-blind method, and compared the CT dose index volume (CTDI_vol), dose-length product (DLP), and effective dose (E) of the two groups. Results: The CT value of the aorta and spinal posterior muscle and the aortic SNR in the test group were (45.38 ± 4.77), (53.41 ± 8.44) HU, and 2.82 ± 0.59, and significantly higher than those in the conventional group [(39.68 ± 6.26), (42.66 ± 6.32) HU, 2.58 ± 0.61, t = 5.608, 7.897, 2.162, P < 0.05]. The aortic noise, CNR and subjective scores between the two groups had no significant difference (P > 0.05). The CTDI_vol, DLP, and E in the test group were (3.09 ± 1.02) mGy, (107.57 ± 32.81) mGy · cm, (1.51 ± 0.46) mSv, significantly lower than those in the conventional group [(7.00 ± 1.80) mGy, (261.65 ± 73.93) mGy · cm, (3.66 ± 1.03) mSv; t = -14.680, -14.756, -14.756, P < 0.05]. Conclusions: In the screening of COVID-19, using low-dose scanning mode of 3-G DSCT combined with iterative reconstruction technology would provide diagnostic quality images and meanwhile effectively reduce the radiation dose and improve the SNR of the image. (authors)