Objective To enhance CT radiation dose management in radiology department via applying Six Sigma management method.Methods The radiation quality control processes in the radiology department were optimized according to the Six Sigma quality management DMAIC pattern.The volume CT dose index(CTDIvol),dose length product(DLP),radiation quality control problems of adult and pediatric CT scans from January 2022 to February 2022 were collected as baseline data,and data collected from August 2022 to September 2022 were taken as the control group for analysis via Six Sigma management method.All data of the dose values and problem rates were compared and analyzed between before and after Six Sigma management methods.Results The DLP in the adult group was decreased by 65.5％in computed tomography urography(CTU),decreased by 25.5％in neck enhancement,decreased by 9.8％in head,decreased by 24％in facial cranial,and decreased by 27.7％in chest enhancement,with a statistical difference(P＜0.05).While DLP in the adult group was decreased by 9.7％in abdominal enhancement,with no significant difference(P＞0.05).The DLP in the pediatric(＜1 year)group was increased by 35％in head scans,with no significant difference(P＞0.05).While the DLP was decreased by 30.2％in 1 to 5 years group,decreased by 21.8％in 6 to 10 years group,decreased by 27.6％in 11 to 15 years group,with statistical difference(P＜0.05).The DLP of facial cranial was decreased by 43.3％in 6 to 10 years group,decreased by 29.1％in 11 to 15 years group,with statistical difference(P＜0.05).The DLP of chest was decreased by 13％in＜1 year group(P＞0.05),increased by 2.2％in 1 to 5 years group(P＞0.05),decreased by 42.6％in 6 to 10 years group,decreased by 54.2％in 11 to 15 years group(P＜0.05).The incidence of radiological quality control problems of after Six Sigma management was significantly lower than that of before Six Sigma management(P＜0.05).Conclusion Six Sigma management method can identify problems in the clinical practice and enhance the ability of radiation quality control through optimization.

Objective To analyze the radiation dose in low-dose chest CT examination of pediatric patients with mycoplasma pneumoniae pneumonia(MPP)by using size-specific dose estimation(SSDE).Methods A total of 95 patients who were scanned with low-dose chest CT were prospectively selected,65 patients with weight ≤50 kg,using 80 kV and DoseRight Z-DOM(30-50 mAs);30 patients with weight＞50 kg,using 100 kV and DoseRight Z-DOM(50-100 mAs).A total of 65 patients who were scanned with conventional chest CT were retrospectively collected,40 patients with weight ≤50 kg,25 patients with weight＞50 kg,using 120 kV,DoseRight Z-DOM(50-100 mAs)and fixed mAs.Image noise,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)were used to objectively evaluate image quality.The subjective evaluation of image quality was performed by two radiologists using a 5-score system and a double-blind method.The volume CT dose index(CTDIvol)and dose length product(DLP)were collected,the SSDE and effective dose(ED)were measured,respectively.Results Compared with conventional scan,CTDIvol,DLP,SSDE,and ED values of 80 kV scan was decreased by 81.3％,80.3％,81.5％,and 82.4％,respectively,with a statistical difference(Z=-8.433,-8.137,-8.146,-8.142,P＜0.05).There were statistically significant differences in image noise,SNR,and CNR between 80 kV scan and conventional scan in patients with weight ≤50 kg(Z=-6.762,-5.075,-3.430,P＜0.05).In 100 kV scan,CTDIvol,DLP,SSDE,and ED values was decreased by 75.7％,76.3％,75.3％,and 75.3％,respectively,with a statistical difference(Z=-6.301,-6.173,-6.347,-6.308,P＜0.05).There were statistically significant differences in image noise and SNR between 100 kV scan and conventional scan in patients with weight＞50 kg(Z=-5.367,-4.650,P＜0.05).The subjective evaluation scores of the two groups images were all greater than 3 points,all images could be used for clinical diagnosis.SSDE was 45.3％and 29.9％higher than CTDIvol for 80 kV and 100 kV scans,respectively,SSDE was 45.7％and 28.8％higher than CTDIvol for conventional scans with weight ≤50 kg and weight＞50 kg,respectively.Conclusion Low kV combined with DoseRight Z-DOM effectively reduces radiation dose to pediatric patients with MPP;SSDE more accurately assesses radiation dose than CTDIvol in children.

Objective:To study preoperative MRI imaging and its enhanced mode on tumor features in predicting microvascular invasion (MVI) in patients with hepatocellular carcinoma (HCC).Methods:The clinical data of patients with a solitary HCC who underwent MRI examination followed by surgical resection at the General Hospital of Ningxia Medical University from January 2017 to June 2019 were studied. The patients were divided into the MVI (+ ) and MVI (-) groups according to the findings on postoperative pathological diagnosis. The relationship between the rates of MVI and MRI tumor features including diffusion weighted imaging (DWI) signal, enhancement mode, enhancement type and other imaging characteristics were analysed.Results:Of 84 patients with HCC enrolled into this study, there were 65 males and 19 females. Their age (Mean±SD) was (54.94±11.51) years. MVI (+ ) was found in 46 patients and MVI (-) in 38 patients. The maximum tumor diameters (Mean±SD) of the two groups were (7.08±3.45) cm and (4.28±2.47) cm ( P<0.01). Single-factor analysis and comparison of imaging characteristics of the two groups of patients showed tumor DWI signal, tumor encapsulation, enhancement mode, tumor edge smoothness, abnormal enhancement around tumors, and intratumoral arteries were significantly different ( P<0.05); There were no significant differences in T 1WI signals, T 2WI signals, tumor periphery, and enhancement types between groups. After inputting MVI(+ ) as a risk factor into the logistic regression model, tumor maximum diameters >6.33 cm, type 3/4 enhancement mode, and unsmoothness of tumor edge were independent risk factors (all P<0.05). Through combined diagnosis using ROC curve analysis with a cut-off value of 0.53, the area under the curve was 0.881, the sensitivity 0.870, specificity 0.789, and the Youden index 0.659. Conclusion:The multivariate logistic regression model and combined diagnosis using ROC curve analysis improved the diagnostic efficacy of MVI in its prediction of HCC on imaging studies. The risk predictors were easy to use and to promote in clinical practice.

Objective:To explore the value of clinical data and MRI image features in predicting and analyzing the degree of differentiation of hepatocellular carcinoma (HCC).Methods:The clinical and imaging data of 180 patients with surgical outcomes of HCC from March 2015 to June 2019 in the General Hospital of Ningxia Medical University were retrospectively analyzed. Alpha-fetoprotein (AFP)、aspartate aminotransferase (AST)、D-dimer、clinical stage、tumor length、apparent diffusion coefficient(ADC)、enhancement types and so on the clinical and imaging data of the poorly differentiated and non-differentiated HCC were compared and analyzed. Multivariate logistic regression was used to predict independent risk factors for poorly differentiated HCC.Results:Of the 180 HCC patients, 121 were moderately and highly differentiated, and 59 were poorly differentiated. Univariate analysis showed that the patient’s age, gender, AFP, AST, D-dimer level, clinical stage, Child-Pugh score, tumor length, whether the capsule was complete, tumor apparent diffusion coefficient, the maximum level ADC value, enhancement type with HCC differentiation degree were correlated(all P<0.05). Multivariate logistic regression analysis showed that the patients' gender ( OR=4.524, P<0.05), clinical stage ( OR=5.598, P<0.05), D-dimer ( OR=8.576, P<0.05), HCC diameter ( OR=0.498, P<0.05), enhancement types ( OR=2.988, P<0.05), tumour ADC value ( OR=0.059, P<0.05) were independent of poorly differentiated HCC risk factor. Conclusion:MRI image features can be used as an effective indicator to predict the degree of HCC differentiation before surgery. It is more valuable to accurately predict the degree of HCC combined with D-dimer and AFP value.

Objective: To explore the optimization of CT urography imaging parameters and the control measures of radiation dose to patients with different body mass index. Methods: A total of 133 patients who were required to undergo CT urography were prospectively selected in terms of three different types of CT urography scan; firstly, conventional parameter scan (120 kV, CARE Dose4D); secondly, low kV scan (BMI ≤ 22.9∶80 kV, 22.9 < BMI < 30∶100 kV, BMI ≥ 30∶120 kV, CARE Dose4D) and thirdly, low mAs scan (120 kV, 40% reduction in mAs on CARE Dose4D). Noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were measured as objective evaluation indicators of image quality. The subjective evaluation of the images was performed by two radiologists who had been working for more than five years using a double-blind method and a 5-score system evaluation. The effective dose values (CTDI_vol, DLP, E) in each group were measured. Results: Patients′ effective dose was decreased by 77.7% in 80 kV group and 38.3% in 100 kV group, with a statistical difference between the two groups (Z=-3.330, -5.559, P<0.05). There was a statistically significant difference in renal cortex noise, SNR, CNR and ureteral noise between the 80 kV scan and the routine scan (Z=-3.705-2.392, P<0.05), but no significant difference in ureteral SNR, CNR and renal pelvis noise, SNR, CNR (P>0.05). There was a statistically significant difference in renal cortex noise and SNR between the 100 kV scan group and the routine scan group (Z=-5.096, -3.566, P<0.05), but no statistical difference in renal cortex CNR, renal pelvis and ureteral noise, SNR, CNR(Z=-5.086, -5.912, -2.842, P>0.05). The effective dose from low mAs scan in the three types of patients was decreased by 38.3%, 32.0%, and 34.7%, respectively, with a statistical difference between them (P <0.05). There was no significant difference in noise, SNR, and CNR between renal cortex, renal pelvis and ureter (P>0.05) besides ureteral CNR in the 22.9 < BMI < 30 group (Z=-2.587, P<0.05). The subjective evaluation scores of all images were greater than 3 points. Conclusions In this study, the scan method for low kV and low mAs used for patients with different body mass index can effectively reduce the radiation dose to patients and meet the requirements of clinical diagnosis.

Objective:To evaluate the radiation doses from head and chest CT examinations of children in Ningxia, and provide basic data for the optimization of CT radiation doses to children of different ages.Methods:By using stratified cluster sampling method , the dose parameters on head and chest CT scanning, CTDI vol and DLP for the children under 15 years old were sampled within 1-2 weeks from hospitals at different levels in different regions of Ningxia for the calculation of effective doses. The 75th percentile (P75) of CTDI vol and DLP was compared with those recommended by other countries. All children included four age groups: up to 1 year old, 1 to 5 years, 6 to 10 years, 11 to 15 years. Results:There were 39 hospitals and 47 CT scanners in this survey, and 1 134 head scanning and 636 chest scanning were investigating. The 75th percentile (P75) of CTDI vol and DLP for head scanning were 44.2 mGy and 456.2 mGy·cm for those up to 1 year old; 57.2 mGy and 659.6 mGy·cm for 1 to 5 years old, 61.1 mGy and 668.7 mGy·cm for 6-10 years old, and 63.6 mGy and 849.3 mGy·cm for 11-15 years old, respectively. The 75th percentile (P75) of CTDI vol and DLP for chest scanning were 5.0 mGy and 89.2 mGy·cm for those up to 1 year old, 5.9 mGy and 124.8 mGy·cm for 1 to 5 years old, 6.0 mGy and 167.9 mGy·cm for 6 to 10 years, and 7.1 mGy and 235.0 mGy·cm for 11 to 15 years old, respectively. Conclusions:The chest CT radiation dose to children in Ningxia is close to the reported values, but the head CT radiation dose is relatively high in all age groups, especially in infants. The optimization and regulation of head CT radiation doses to children in Ningxia should be strengthened. It is high time to increase dose awareness for pediatricians and radiologists and raise awareness of radiation-related risks.

Objective:To analyze the hepatic hemodynamics changes after partial splenic embolization in patients with cirrhosis and hypersplenism.Methods:A total of 26 patients with cirrhosis and hypersplenism who underwent partial splenic embolization in the General Hospital of Ningxia Medical University from April 2018 to June 2019 were included in this study. The clinical data was retrospectively studied. The study objects consisted of 19 males and 7 females with an average of 55 years. Whole-liver perfusion enhanced CT imaging scan was performed for all patients. Changes in laboratory indexes and the blood perfusion of the liver sections including hepatic arterial perfusion, portal venous perfusion, total liver perfusion and hepatic arterial perfusion indexes before PSE and postoperative 1 month were compared.Results:The postoperative leukocyte and platelet counts increased, and the prothrombin time decreased in the 26 patient, and the differences were significant ( P<0.05). The hepatic arterial perfusion of the left lateral section, left medial section, right anterior section and right posterior section increased in postoperative 1 month, from 10.0 (7.0, 13.5) ml·min -1·(100 ml) -1, 9.3 (5.4, 12.8) ml·min -1·(100 ml) -1, 8.0 (6.0, 11.2) ml·min -1·(100 ml) -1, 10.7 (7.1, 13.8) ml·min -1·(100 ml) -1 to 7.7 (4.2, 11.0) ml·min -1·(100 ml) -1, 6.9 (2.6, 10.2) ml·min -1·(100 ml) -1, 7.1 (4.1, 8.7) ml·min -1·(100 ml) -1, 5.9 (4.4, 8.5) ml·min -1·(100 ml) -1, respectively. The differences were all significantly different ( P<0.05). There were no significant difference in portal venous perfusion and total liver perfusion before and after operation ( P>0.05). The hepatic arterial perfusion index of left lateral section, right anterior section and right posterior section increased after operation ( P<0.05). Conclusion:For patients with cirrhosis and hypersplenism who underwent partial splenic embolization, the state of hypersplenism was relieved, the hepatic arterial blood flow increased, and the liver function improved.

Objective:To investigate the differences and changes of blood flow status of splenic volume, common hepatic artery, splenic arteriovenous, inner diameter of portal vein and hepatic in patients with hypersplenism of different degrees using multi-slice spiral CT whole-liver perfusion model.Methods:42 cases with hypersplenism of chronic hepatitis B with cirrhosis and 15 cases without hepatosplenic disease were collected as controls. All patients underwent multi-slice spiral CT whole-liver perfusion imaging. (1) The differences of spleen volume, common hepatic artery, splenic arteriovenous, and portal vein diameter between different degrees of hypersplenism and the control group were measured and compared. (2) The correlation between spleen volume and the inner diameter of each related vessels were analyzed and compared. (3) The values of perfusion parameters related to the five lobes of the liver in Couinaud segments based on hepatic artery perfusion (HAP), portal venous perfusion (PVP), total hepatic perfusion (TLP) and hepatic artery perfusion index (HPI) were measured and compared. One-way ANOVA was used to analyze the measurement data. The correlation between the spleen volume and the inner diameter of each blood vessel was analyzed by Pearson’s correlation analysis.Results:(1) spleen volume and the inner diameter of splenic artery, splenic vein and portal vein in the cirrhotic hypersplenism group were significantly larger than control group, and the difference was statistically significant ( F = 37.108, 17.484, 23.124, 13.636, P < 0.05). (2) spleen volume and the inner diameter of splenic artery, vein and portal vein in the moderate and severe hypersplenism groups were significantly larger than the mild hypersplenism group, and the difference was statistically significant ( F = 25.418, 13.293, 15.136, 7.093, P < 0.05), but there was no statistically significant difference between the moderate and severe hypersplenism groups ( P > 0.05). (3) The inner diameter of splenic vein, portal vein, and splenic artery was positively correlated with spleen volume ( r = 0.680, 0.548, and 0.726). (4) PVP and TLP of the whole liver in hypersplenism group were lower than control group ( P < 0.05), and the differences were statistically significant ( P < 0.05). HPI in the right posterior lobe of the liver in the moderate and severe hypersplenism group was higher than mild hypersplenism group ( F = 3.555, 4.570, P < 0.05), and there was no significant difference in the HAP in the whole liver among the groups ( P > 0.05), but the HAP in the whole liver in the severe hypersplenism group was lower than control, mild and moderate hypersplenism group. Conclusion:The inner diameter of the splenic arteriovenous in patients with hypersplenism of different degrees has widened to varying degrees, and is consistent with the increase in spleen volume, particularly in moderate and severe cases. Portal venous perfusion and total liver perfusion in patients with hypersplenism of different degrees have declined and the hepatic arterial perfusion in patients with severe hypersplenism is significantly reduced.

Objective:To investigate the blood flow change status in early stage tumor-related areas of hepatocellular carcinoma and its clinical significance after radiofrequency ablation using multi-slice spiral CT whole-liver perfusion imaging technology.Methods:21 cases of primary liver cancer that underwent CT-guided radiofrequency ablation were included. CT perfusion scans were divided into four groups according to the time points of CT scans (before surgery, immediately after surgery and 1 and 3 month after surgery), and then blood perfusion parameters of the corresponding areas of the tumor were measured. Statistical analysis was performed using two independent samples of non-parametric Wilcoxon rank-sum test. The differences of blood perfusion parameters between tumor or ablation lesion and background liver parenchyma, paratumor tissue or inflammatory response zone were compared before, immediately and 1 and 3 months after surgery, respectively.Results:(1) The hepatic arterial perfusion (HAP) and hepatic arterial perfusion index (HPI) of cancerous liver tumors and background liver parenchyma was significantly increased ( P < 0.01). The total liver perfusion (TLP) was higher than the background liver parenchyma ( P = 0.01 < 0.05). The time to peak (TTP) was significantly lower than background liver parenchyma ( P < 0.01); (2) The perfusion parameters of HAP, PVP and TLP were lower than the background liver parenchyma in the complete ablation lesions immediately after radiofrequency ablation and 1 and 3 months after surgery, and the difference was statistically significant ( P < 0.05); (3) The inflammatory response zone of ablation lesions of HAP, HPI, and TLP were gradually decreased with the extended postoperative time and TTP was gradually increased, while PVP did not change significantly; (4) HAP, HPI, and TTP were compared between the tumor and the tumor inflammatory response zone immediately after surgery, and 1 and 3 months after surgery, and the difference was statistically significant ( P < 0.01). However, there was no statistically significant difference between PVP and TLP ( P > 0.05). Conclusion:CT whole-liver perfusion imaging can precisely evaluate the early stage blood flow change status in peritumor and tumors before and after radiofrequency ablation and then objectively evaluate tumor’s blood supply and therapeutic effect on hepatocellular carcinoma.

Objective: To investigate the current status of CT radiation dose to adults in Ningxia, and provide basic data for developing the first diagnostic reference level of adults from CT scanning. Methods: Stratified cluster sampling method was used to investigate the in-service status of CT scanners with various brands and different models in different grades of hospital in Ningxia. Interval sampling method was used to obtain everyday′s scanning parameters and radiation dose values from different types of scanning examinations in surveyed hostipitals. Basic information was collected include hospitals, CT scanner, scanning types and patients. CT scanning parameters, CTDI_vol and DLP values were recorded, with effective dose values calculated. The data were statistically analyzed by examination types and comparation was made with the DRL values recommended by other countries. Results: Finally, there were 45 medical institutions in this study, including 10 public tertiary A hospitals, 5 public tertiary B hospitals, 23 public secondary A hospitals, 5 private hospitals and 2 physical examination centers. 58 CT scanners from 6 manufacturers and 4 952 adult patients were investigated. The 75th percentile (P₇₅) of CTDI_vol, DLP, and E values of common scanning examinations were listed as follows: 65.67 mGy, 860.74 mGy·cm, and 1.64 mSv in skull scanning; 29.32 mGy, 490.00 mGy·cm, and 2.83 mSv in neck scanning; 36.92 mGy, 954.42 mGy·cm, and 4.87 mSv in neck enhanced scanning; 11.50 mGy, 382.06 mGy·cm , and 5.68 mSv in chest scanning; 45.80 mGy, 1 713.22 mGy·cm, and 25.01 mSv in chest enhanced scanning; 20.10 mGy, 506.59 mGy·cm, and 7.75 mSv in upper abdominal scanning; 50.07 mGy, 1 434.19 mGy·cm, and 21.94 mSv in upper abdominal enhanced scanning; 14.33 mGy, 670.78 mGy·cm, and 10.26 mSv in abdominal-pelvic scanning; 48.00 mGy, 2 294.00 mGy·cm, and 35.10 mSv in abdominal-pelvic enhanced scanning; 16.10 mGy, 471.58 mGy·cm, and 6.08 mSv in pelvic scanning; 31.04 mGy, 1 138.78 mGy·cm, and 14.69 mSv in pelvic enhanced scanning. Conclusions The CT scanning radiation doses to skull, neck, chest and pelvis in Ningxia are slightly lower than, or similar to, in other countries, but the abdominal scanning dose is significantly higher than that in other countries. It is necessary to optimize the abdominal CT scanning protocol.