Clinical Application Of Wide-detector CT In Chest Scanning Of Patients Who Can Not Cooperate With Breath-holding

ObjectiveMany experts and scholars have proved that the degree of respiratory coordination of lung CT scan is very important,which directly affects the image quality,and then affects the accurate diagnosis of diseases.The Lung CT scanning of patients who can not cooperate with breath-holding becomes the focus of clinical attention.The purpose of this study was to explore the clinical value of 16 cm wide body detector CT in chest scanning of patients who can not cooperate with breath-holding.Objects and MethodsA total of 100 patients who could not cooperate with breath-holding were prospectively included in the study.The subjects were randomly divided into experimental group and control group,50 cases in each group.The experimental group used a 16 cm wide-detector with a collimation width of 256×0.625 mm,while the control group used an 8cm ordinary-detector with a collimation width of 128×0.625 mm.Other scan parameters were the same: tube voltage of 120 k V,rotational speed of 0.32 s,pitch0.90,filter parameter F20,the same reconstruction parameters.The patient’s age,height,weight and body mass index(BMI)were recorded.The image quality assessment included subjective and objective assessment.The subjective assessment was evaluated by two senior physicians doctors according to five-point method.Objective evaluation was carried out by three senior physicians in a doubleblind setting.The effective radiation dose(effective dose,ED),contrast to noise ratio(contrast to noise ratio,CNR),signal to noise ratio(singal to noise ratio,SNR)and standard deviation(standard deviation,SD)were calculated,the area of region of interest(ROI)is 10-20mm2,and the average value is used as statistical data.SPSS26.0software was used to analyze the data.The data were expressed in the form of mean±standard deviation.The intra-group correlation coefficient(INTRACLASS correlation coefficient,ICC)was used in the inter-observer consistency analysis.The dose-length product(dose length product,DLP),effective dose(ED),contrast to noise ratio(CNR)and signal to noise ratio(SNR)were compared between the two groups by independent sample t-test.Mann-whitney rank sum test was used to compare the subjective quality scores of the two groups,P < 0.05 for the difference was statistically significant.ResultsThe mean of subjective evaluation of image quality was 4.11±0.45 in experimental group and 4.17±0.41 in control group,and 4.05±0.21 in experimental group of right lower pulmonary trunk section,the scores of the control group were 4.09±0.28,the experimental group and the control group were 4.12±0.51 and 4.23 ± 0.43,respectively.CTDIvol was 14.5 m Gy in the experimental group and 4.61±1.00 m Gy in the control group.The mean total dose(DLP)was 1471.02±345.25 m Gy in the experimental group and 4561.70±346.32 m Gy in the control group,and the mean effective radiation dose(ED)was 20.59±4.83 m Gy in the experimental group and 63.86±4.85 m Gy in the control group,the SNR and CNR of the two groups were statistically analyzed(P >0.05).The average exposure time of the experimental group was 1.01±0.16 s,and that of the control group was 4.07±0.12 s.There was no significant difference in CNR、SNR between the experimental group and the control group at the level of main pulmonary artery,right inferior pulmonary trunk and aortic arch(P > 0.05).The results showed that there was a high consistency of subjective score among observers(> 0.75 indicated good consistency),and the scores of both groups were above 4 points,the results show that the image quality of 16 cm detector can meet the requirements of clinical diagnosis,and there is no statistical difference between 16 cm detector and 8cm detector.The scores of pulmonary aorta,right inferior pulmonary vein trunk and aortic arch were all more than 0.75,indicating excellent consistency.There was no significant difference in SNR,CNR and image quality between wide-detector and commondetector,and the scanning time of wide-detector was 75.18% shorter than that of common-detector,the scanning time of wide-detector is shorter than that of common detector.The results were in line with previous expectations.ConclusionStatistical analysis showed that the 16 cm wide body detector CT significantly reduced the radiation dose and scan time of patients compared with the conventional detector CT without any difference in the image quality of the chest scan,it has high application value for clinical rapid diagnosis and treatment.