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Objective To explore the application value of 320 slice spiral CT personalized scanning of pulmonary angiography and the reduction of radiation dose.Methods from 2014 to 2016 in our hospital 200 cases with suspected pulmonary embolism were recruited in our study and received 320-slice spiral CT pulmonary artery angiography examination.40 cases with CT configuration of the original scanning parameters(120kV,300mA,0.45s/r)and the recommended contrast velocity and amount 眀攀爀攀 treated as a control group; According to the BMI,160 patients were divided into four groups(A,B,C,D)with 40 cases in each group.Group A with BMI<18.5,scanning parameters of 100 kV,250mA were used.Group B with BMI 18.5-23.9,scanning parameters of 100 kV,300mA were used.Group C with BMI 24-27.9 scanning parameters of 120 kV,250mA were used.Group D with BMI is greater than or equal to 28,scanning parameters of 120 kV,350 mA were used.Rotation speed 0.45s/r,the scanning field LL(maximum scanning field)were adopted in group A,B,C and D with contrast agent flow rate of 4.0-6.0mL/s and total amount of 50-80ml.Scanning was performed according to the patients lung morphology on the reasonable scanning range,patients receiving radiation dose was recorded after scanning.Data was post-processed with MIP,VR reconstruction and double blind analysis was carried out by two senior radiologists.According to the branch vessels showing condition,four-grades including excellent,good,meet the diagnosis,and unqualified were assessed.Statistical analysis 眀愀猀 carried out using SPSS13.0,and P < 0.05 considered the differences are statistically significant.Results In group A,the radiation dose was 4.08-5.34mSv,and image quality was determined as the unqualified(n = 4),meet the diagnosis(n = 3),good(n = 28),and excellent(n= 5),respectively.In group B,the radiation dose was 4.87-6.43mSv,and image quality was determined as the unqualified(n = 2),meet the diagnosis(n = 3),good(n = 20),and excellent(n= 15),respectively.In group C,the radiation dose was 6.70-8.79 mSv,and image quality was determined as the unqualified(n = 3),meet the diagnosis(n = 6),good(n = 20),and excellent(n= 11),respectively.In group D,the radiation dose was 9.32-12.30mSv,and image quality was determined as the unqualified(n = 1),meet the diagnosis(n = 3),good(n = 15),and excellent(n= 21),respectively.In control group,the radiation dose was 8.02-10.55mSv,and image quality was determined as meet the diagnosis(n = 4),good(n = 7),and excellent(n= 29),respectively.There was a great difference between group A and the control group,P=0.02<0.05.No difference was found among group B,C and D.Conclusion Individualized scanning of pulmonary artery according to the body mass index(BMI)has important application value,which can effective reduce the radiation dose and the risk of allergy at the same time with the adjustment of the flow of the contrast agent.