The Application Research Of Low-dose CT Scan In Lumbar Based On The Body Mass Index And The Waistline

Part IObjective: Conducting basic research and using the iterative reconstruction technique i Dose4 to investigate the feasibility of the individualized reduction tube current for lumbar CT scan,and to obtain the reference parameters of the low-dose CT scan of the lumbar spine.Methods: Select a pig lumbar segment and the surrounding muscles,make four lumbar spine models by imitating man's waist,respectively,less than 70 cm,70 ~ 80 cm,80 ~ 90 cm,90 ~ 100 cm.They were well packed and scanned for the lumbar model.For the same lumbar model,the scanning parameters are: helical scan,120 KV,collimation 64*0.625 mm or 128*0.625 mm,i Dose4 reconstruction algorithm,reconstruction layer thickness 1 mm,reconstruction layer interval 0.5 mm,FOV200 mm or 250 mm,scanning range of 80 mm;According to the positioning,set the tube current(m As),scanning each time decreasing 20 m As.All inages are read by two experienced experts repectively(5 ").Compare each scan data and images and tranamit the original and reconstructed images to the PACS system.Results: The scanning parameters obtained by the scanning of four lumbar models were : less than 70 cm,and the tube current was 130 m As;Waist circumference 70 ~ 80 cm,tube current 140 m As;Waist circumference 80 ~ 90 cm,tube current 160 m As;Waist circumference 90 ~ 100 cm,tube current 180 m As.The images obtained by these four parameters can be rated as excellent,and the images obtained by scanning location like the given tube current scan are not significantly different,while the radiation dose is reduced in different degrees.Conclusion:The personalized scanning of the lumbar model can be operable.Calculate the circumference of the lumbar spine,and determine the optimal combination point of an image and the scanning scheme according to the score and the body surface circumference of the sample.Part IIObjective: Apply the model of lumbar CT scanning personalized low-dose scan parameters to clinical examination,to test feasibility of lumbar CT examination of personalized scanning and the ability to reduce the radiation dose.Methods: 100 patients with CT scan of the lumbar spine were required,ranging from 18 to 50 years old.The patients are randomly divided into control group(group A,35 cases),experimental group(group B,35 cases),and experimental group(group C,30 cases).With the control group(A)as the conventional parameters scanning,The parameters are: 120 kv,64 * 0.625 mm,collimating i Dose4 reconstruction algorithm,reconstruction of 1 mm thick,reconstruction interval 1 mm,FOV200 mm,tube current for positioning as scanning given m As;With the Experimental group(B)and group(C)for the personalized scanning,the parameters are: 120 kv,and other parameters are the same as group A,according to the inspectors of body mass index,and the direction of the measured flat belly button around after and before and after the size,calculate the waistline,tube current(m As)respectively is set to the scanning parameters of the lumbar spine model increase 40 ~ 50 m As and 20 ~ 30 m As.Record the radiation dose and effective dose groups,respectively,the original images and the reconstructed images are transmitted to the PACS system,reading by two experienced experts to have blind image quality assessment(5 ").The radiation dose and image quality scores of group(A,B and C)were statistically analyzed by SPSS statistical software 20.Results: The radiation dose of experimental group(group B and C)is significantly lower than the control group(A),the dose of experimental group(B)(4.76 ± 0.93)m Sv is lower than the control group(A)(7.49 ± 1.47)m Sv 36%;the dose of experimental group(C)(4.27 ± 0.46)m Sv is lower than the control group(A)doses(7.49 ±1.47)m Sv 43%.The dose of experimental group(C)(4.27± 0.46)m Sv is slightly lower than the experimental group(B)(4.76 ±0.93)m Sv 10%.The image quality scores of the three groups were all above(3.7 ±0.38),which can meet the diagnostic requirements.Conclusion: By using the iterative reconstruction technique i Dose4,the individualized low-dose scanning scheme for lumbar CT examination is feasible and can reduce the radiation dose significantly.