| Objective:By collecting inspiratory and expiratory phase CT scan data, USES the gemstone CT ofadaptive statistical iterative reconstruction (ASiR) technique, and by using post-processingsoftware Thoracic VCAR lung function parameters measurement, and the image quality aresubjective ratings, thus reduce the radiation dose in the process of checking and reached thefeasibility of the image quality is clear.Methods:Randomly selected from health physical examination in patients with60cases patients,randomly divided into three groups, each group20cases, lines of precious stones energyspectrum CT chest breathing bipolar breathless scanning, the noise index (whose index, NI)values were set to11group A and group B, group C1723scanned, then ASiR weighting isset to10%~10%respectively for image reconstruction, the use of post-processingsoftware Thoracic VCAR analysis of image data, get the following three sets of data:1、WTAvg、WT/D、WAR、WA；2、PI:1024~-910Hu，-910~-800Hu，-800~-700Hu，>-700Hu；3、CTDIvol、DLP，ED。Results: the evaluation of each group have statisticaldifference between measuring parameters. Image quality score by three experiencedphysicians, blinded evaluation method, review each image obtained evaluation criteria forthe lung bronchus the neurovascular bundle posteriorly and mediastinal soft tissueboundary conditions, clear lung field and image noise, image quality evaluation rating byfour point,2points or higher image quality meet the diagnostic requirements. Results:1,Using software SPSS19.0, paired T test is used to analyze the experimental data:(1) A,B two groups of subjects the upper tip period of airway parameters between WTAvg, WT/D,WAR, WA p value: Plin were0.071,0.820,0.194,0.820, and the place were0.617,0.745,0.713,0.472; B, C P values between the two groups: Plin were0.770,0.102,0.392,0.770,place were0.174,0.315,0.061,0.596; A, C p values between the two groups: Plin were0.575,0.830,0.368,0.575, place were0.772,0.302,0.276,0.965; Had no statisticaldifference between the various data (P>0.05).(2)A, B two groups of subjects lung volumeparameter Vex, Vin and Vex/Vin,(Vin-Vex)/Vin between p value:0.375,0.621,0.513,0.621; B, C p values between the two groups:0.309,0.988,0.377,0.988; A, C p valuesbetween the two groups:0.714,0.315,0.560,0.315, had no statistical difference betweenthe various data (p>0.05).（3） A, B two groups of subjects double lung regions pixelindex (P value: Plin respectively,0790,0.906,0.794,0.134, place were0.697,0.578,0.530,0.697; B, C p values between the two groups: Plin were0.881,0.766,0.508,0.622, placerespectively0,0.383,0.973,0.645; A, C p values between the two groups: Plin were0.676,0.275,0.419,0.433, place were0.722,0.305,0.129,0.920; Between groups had nostatistical difference between the various data (p>0.05).2,Radiation dose: along with the increase of NI, radiation dose decrease gradually, ED A,B, C three groups were6.25,2.56,1.49, compared with A, B two group C group reducedby59.04%and59.04%respectively.Quality score gradually decline, which is almost thesame quality grade A, B two groups, group C image quality score significantly decreasedcompared with A, B two groups.3, ASiR weighting: with the increase of ASiR weighting, to noise ratio (SD) is falling,image quality score increased, peak in50%~70%, while more than70%after imagequality score gradually decline,50%is the best setting.4,This study argues that when NI=17(group B), image quality score is no obviousdifference was found between group A, can ensure the quality of image cases, significantlyreduce the radiation dose, and the implementation of the evaluation of pulmonary function; But when NI=23(C group), while the image quality score decreased, but the parametersmeasured results, and the former two groups no significant statistical differences of theairway wall quality measurement method than other scores are relatively high, and theresults obtained with the difference between the two groups is small, so the author thinksthat the scanning conditions set to NI=23, ASIR%is set to50-70%, airway wallmeasurement method also can meet the requirements of diagnosis of pulmonary functionevaluation.Conclusions:1, Use gem CT adaptive statistical iterative reconstruction (ASiR) technique, can reducethe radiation dose of at the same time, significantly improve the image quality, andimplement the evaluation of pulmonary function.2, When NI=17, ASiR%weight set to50-70%, on the premise of can ensure the qualityof image, significantly reduce the radiation, and the implementation of the evaluation ofpulmonary function, is best set gem CT measurement of pulmonary function.3, When NI=23, ASiR weight set to50-70%, while the lower image quality score, butalso can realize to the evaluation of pulmonary function, airway wall measurement methodis the best measurement method. |
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