ABSTRACT
Objective:To explore a low dose CT scanning method on novel coronavirus (COVID-19) pneumonia based on infection prevention and control.Methods:A total of 140 patients with confirmed novel coronavirus pneumonia in Xiehe hospital from January 20, 2020 to February 28, 2020 were undertaken CT scan and divided into low dose group and conventional dose group. The patients in low dose group(120 kV, 31 mAs) consisted of mild type(51), severe type(15) and critically ill type(4); and those in conventional dose group(120 kv, adaptive milliampere second) consisted of mild type(48), severe type(17) and critically ill type(5). The effective radiation dose, SNR and CNR of CT scan were compared between two groups. A senior and a middle radiologist made the image subjective quality scores, respectively.Results:The effective dose in low dose group was lower than that of conventional dose group( t=-48.343, P<0.05). There was no significant difference in SNR and CNR between two groups( P>0.05). For severe and critically ill patients, the score in low dose group was significantly lower than that in conventional dose group( t=-2.781, P<0.05). There was no significant difference in scores between two groups for mild patients( P>0.05). Conclusions:Low-dose CT scanning could meet the image quality needs for patients with COVID-19 and meanwhile significantly reduce the radiation dose.
ABSTRACT
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.