The Clinical Application Research Of Dual-source CT Low-dose Technology In Chest

Part Ⅰ The application of Lower tube voltage combine SAFIRE in the chest CT scanObjectiveTo evaluate the clinical application value of Dual-source CT lower tube voltage combine SAFIRE in the chest scanning.Materials and methods300 patients were selected who suspected with chest lesions and need chest CT scan. Included standard:BMI In the normal range (male:20 kg/m2<BMI<25 kg/mz2, female:19 kg/m2<BMI<24 kg/m2), the patients were divided into three groups(A、B、C) according to the scanning time:the tube voltage of each group was120 kV、100kV、80kV, and their tube current were 80 mAs. CARE DOSE 4D were all opened in the there groups. After scanning,we can get six groups of images by uesing FBP and SAFIRE3, such as FBP-A、 FBP-B、FBP-C、SAFIRE-A、SAFIRE-B、SAFIRE-C. To measure the average CT value、 Image noise、signal-to-noise ratios (SNR) and contrast to noise ratios (CNR) in the level of apex right side of the pectoralis major、descending aorta of tracheal bifurcation plane、Left atrium in central. The CT dose indexes of volume(CTDIvol), dose length product(DLP) and effective doses(ED) were recorded and compared between groups. Then make subjective ratings about images of these six groups.Results(1) Three groups of the same tube voltage and with different reconstruction methods CT value have no statistical significance (p>0.05). The image noise、SNR、CNR of the same tube voltage with different reconstruction mode have statistical significance (p<0.05), compared with FBP, noises is obviously decreased in the reconstruction of SAFIRE. (2) The CT value、SD、SNR、CNR in group SAFIRE-A and group SAFIRE-B have no statistical significance (all p>0.05). The CT value have no statistical significance in group SAFIRE-A and group SAFIRE-C (p>0.05), SD、SNR、CNR have statistical significance (p<0.05), compared with SAFIRE-A, SD is obviously increased in SAFIRE-C, and SNR, CNR is decreased. The CT value have no statistical significance in group SAFIRE-B and group SAFIRE-C (p>0.05), SD、SNR、CNR have statistical significance (p<0.05), compared with SAFIRE-B, SD is obviously increased in SAFIRE-C, and SNR、CNR is decreased. (3) The average scores of these six groups(FBP-A、B、C and SAFIRE-A、B、C) in lung window were:4.54±0.18、4.43±0.14、4.32±0.10、4.80±0.20、4.52±0.19、4.43±0.15, the image quality is slightly lower in group SAFIRE-C, which has no statistical significance with group SAFIRE-A and group SAFIRE-B. The average scores of these six groups(FBP-A、B、C and SAFIRE-A、B、 C) in mediastinal window were:4.40±0.20、4.22±0.31、2.66±0.17、4.42±0.20、 4.25±0.19、2.98±0.15, the image quality is decreased obviously in group SAFIRE-C which has statistical significance with group SAFIRE-A and group SAFIRE-B. (4) The radiation dose in group-A、B、C were (2.34±1.02) mSv、(1.59±0.89) mSv、(0.96±0.20) mSv. The radiation dose in group C was the lowest, and it have statistical significance in three groups. Group C compared with A、B, radiation dose decreased about 58.97%、58.97% respectively.Conclusion(1) SAFIRE reconstruction can reduce noise and improve image quality. (2) In the chest scan with Dual-source CT, using the lower tube voltage 80 kV combine SAFIRE3 reconstruction, can significantly reduce the radiation dose, but the mediastinal window image cannot meet the demand of clinical diagnosis. (3) In the chest scan with Dual-source CT, using the lower tube voltage 80 kV combine SAFIRE3 reconstruction, can reduce the radiation dose while guarantee the satisfied image quality.Part Ⅱ The clinical application of CARE kV technology in chest CT enhanced scanningObjectiveTo study the value of CARE kV technology in chest CT enhanced examination.Materials and Methods320 cases underwent chest CT enhancement scanning who were suspected has chest lesions were randomly divided into two groups, all set 80 mAs for quality reference value. Group A:160 patients underwent chest scan with 120 kV, CARE kV technique, Group B:160 patients underwent chest scan only with 120kV. The two groups received the same dose and concentration of contrast medium. The CT values, image noise(SD),signal-to-noise ratios (SNR) and contrast to noise ratios(CNR) in the level of apex lung, descending aorta bifurcation of trachea and middle area of left atrium were measured and calculated. The CT dose indexes of volume (CTDIvol), dose length product(DLP) and effective doses(ED) were recorded and compared between groups. The image quality was assessed with 5-point scale.ResultsThe images in both groups could satisfy diagnosis requirement. The CT values in the level of apex of lung between two groups have no significant difference(P>0.05), while the CT value in the level of middle area of left atrium, descending aorta bifurcation of trachea between two groups have no significant difference(P<0.05). The image noise (SD) in group B was lower than that in group A, and the difference has significant difference (P<0.05). The signal-to-noise ratio (SNR) in group B was higher than that in group A, in the level of apex of lung between two groups have significant difference(P<0.05), while the CT value in the level of middle area of left atrium, descending aorta bifurcation of trachea between two groups have no significant difference(P>0.05). The CTDvol, DLP and ED were (4.66±1.00)mGy、(151.74±32.58) mGy/cm、(2.12±0.46) mSv in the group A, while (6.29±2.10)mGy、(208.14±80.37)mGy/cm、(2.91±1.13)mSv in group B, the differences all have statistical significance(all P<0.05). The ED in group A than in group B decreased 27.15%.ConclusionCARE kV scanning in chest CT enhancement examination could satisfy the requirement of diagnosis, improve the contrast of image while significantly reduce the radiation dosage, which has a certain clinical value.Part Ⅲ The application of CARE kV technique combined with SAiterative reconstruction in chest CT scanning of overweight patientsObjectiveTo study the clinical application value of CARE kV combined with SAFIRE iterative reconstruction in chest CT scanning of overweight patients.Materials and Methods100 cases underwent chest DSCT scanning for overweight patients(male:25 kg/m2≤BMI,female:24kg/m2≤BMI) who were suspected chest lesions. Randomly divided into two groups according the scan time, scan range from the thoracic inlet to the bottom of the lung. A group:50 cases underwent chest scan with tube voltage 120 kV and the reference tube current 50mAs, adopting tube current automatic control technology (CARE Dose 4D) and shut down CARE kV technique. B group:50 cases underwent chest scan with CARE kV technique, The other scanning conditions were consistent to the group A, SAFIRE (value=3) reconstruct group B images to get group C. The CT values. The image noise (SD), signal-to-noise ratios (SNR) and contrast to noise ratios(CNR) in the level of apex lung, descending aorta bifurcation of trachea and middle area of left atrium were measured. The CT dose indexes of volume (CTDIvol), dose length product(DLP), effective doses(ED) and subjective rating were recorded and compared between groups.ResultsThere was no significant difference of the CT values between three groups (P>0.05). There was statistical difference in the image noise(SD) between group B with group A, C, but it was no significant difference between group A and group C. the signal-to-noise ratio (SNR) and contrast to noise ratio (CNR) in group A was higher than that in group B, the difference has statistical significance(P<0.05), there were no significant difference of the SNR and CNR between group A and group C (P>0.05). The image quality average score of group A, B and C were 4.53±0.16,4.46±0.25,4.63±0.21, there was no significant difference between the groups (P>0.05). All of he image quality score were more than 4.0 points and could satisfy diagnosis requirement. CTDIvol, DLP and ED in group B were 2.2mGy(decreased about30.09%)、38.5mGy. cm(decreased about21.28%) and 0.54mSv(decreased about21.34%) than in the group A, the difference had statistical significance(all P<0.05).ConclusionCARE kV combined with SAFIRE iterative reconstruction in chest CT scanning of overweight patients could improve CT image quality to satisfy diagnosis, while reduce radiation dosage significantly.