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Application with adaptive statistical iterative reconstruction and low radiation in the pulmonary angiography
- ZHAO Yongxia, CHANG Jin, ZUO Ziwei, ZHANG Changda, ZHANG Tianle, MENG Bo, LI Dan,ZHANG Linlin, ZHU Changyue, LI Shenglan
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2015, 32(3):
16-21.
DOI: 10.3969/j.issn.1674-490X.2015.03.004
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Objective To investigate the effect of adaptive statistical iterative reconstruction and low radiation on the image quality of CT pulmonary angiography. Methods 150 patients whose body mass index was from 20 to 25 were divided into 5 groups underwent pulmonary angiography on a GE HD 750 CT scanners. The scanning range was from 260mm to 310mm, the first group of scan parameters were 120kV,400mAs, it was the acquiescent
parameters of the CT scanner. Reconstruction was performed with ASIR, then the signal to noise ratio (SNR) and contrast to noise ratio(CNR) were calculated. The images of different strength of ASIR were read by 2 independent radiologists with 5-point-scale, then based 120kV, the other group patients were scaned with 350 mAs, 300 mAs, 250 mAs, 200 mAs, recorded the CTDIvol and DLP in different mAs. The effective dose (ED) was calculated
based on the DLP, The SNR and CNR were calculated and the image quality were assessed by the two experienced readers. Results The images were assessed under different mAs (400 mAs, 350 mAs, 300 mAs, 250 mAs, 200 mAs) and the 120kV at the strength of 3, the values of the SNR and CNR were 22.95, 22.90, 21.82, 20.80, 20.83 and 23.61, 22.88, 22.86, 21.93, 21.97. The values of from 400 mAs to 200 mAs by two independent radiologists
were 4.59±0.32, 4.48±0.30, 4.82±0.28, 4.28±0.36, 4.15±0.38. The CTDIvol and DLP of different mAs (400 mAs,350 mAs, 300 mAs, 250 mAs, 200 mAs) were 13.84 mGy, 11.18 mGy, 9.31 mGy, 8.25 mGy, 7.38 mGy and 351.21 mGy, 312.32 mGy, 286.26 mGy, 233.52 mGy, 206.08 mGy. the ED were 5.27 mSv, 4.68 mSv, 4.29 mSv,3.50 mSv, 3.09 mSv. Statistical analysis was performed using analysis of variance, and the date was not statistically significant(F=5.285, P＞0.05) at the exposure factors of 200 mAs, 250 mAs, 300mAs, 350mAs than 400 mAs, but the CTDIvol and DLP of 200mAs were reduced 46.7% and 41.3%, the ED was reduced 41.3%. respectively than the 400 mAs. Conclusion The best mAs is from 200 mAs for the average person whose BMI is from 20 to 25 in CTPA. For smaller (less muscle) or emphysema and other diseases it can be choosen from 180 mAs to 200 mAs.
