Objective To study the effect of image quality and radiation dose by using Z -axis automatic tube current modulation(ATCM),as well as the application of automatic tube current modulation technology.Methods A control group consisting of 25 patients underwent cervical MDCT with fixed-current technique(100-220mA).Of two study groups of 25 patients,one underwent cervical MDCT using z-axis ATCM with the noise index of NI10 and tube current intensity of 80-480 mA,and the other with the noise index of NI12.5 and tube current intensity of 80-369 mA.The noise and mean tube current-time products(mAs) were recorded.Two radiologists evaluated images for diagnostic acceptability.Results All CT examinations of study and control groups were diagnostically acceptable,though objective noise was different with z-axis ATCM than with fixed current.ATCM resulted in significant radiation dose reduction(NI10,94.8?17.9 mAs;NI12.5,74.8? 18.3 mAs),when compared with the fixed current(130.4?43.1 mAs).Conclusion Z-axis Automatic mA technique has no significant change in image quality when compared with the fixed mA technique,but the radiation dose is decreased by 27%(NI10) and 43%(NI12.5),for MDCT evaluation of neck.NI has to be selected on the basis of the tissue,lesion size and nature.

The construction of 64-slice-dual-source computed tomography(DSCT) is introduced.Its imaging principle and clinical application are put forward.DSCT has special advantages in diagnosing coronary stricture.The principles of DSCT and energy subtraction imaging are expatiated in detail.DSCT has great value in clinical research and application.

Objective To evaluate the radiation dose and image quality of MinDose techniques in dual-source CT coronary artery angiography.Methods 120 consecutive patients undergoing cardiac CT scans were randomly assigned into 2 groups: Group A1 with the tube current reduced to 20% of the normal tube current outside the pulsing window,and Group A2 with the tube current reduced to 4% of the normal tube current outside the pulsing window (MinDose).The image quality,noise,volume CT dose index (CTDIvol),and effective dose (E) of these two groups were evaluated.Results The mean score of imaging quality of Group A1 was (4.3 ± 0.3 ),not significantly different from that of Group A2 [(4.5 ±0.4),t=0.16,P＞0.05].The value of CTDIvol of Group A1 was (40.2 ±9.6) mGy,significantly higher than that of Group A2 [( 36.4 ± 9.1 ) mGy,t = 3.2,P ＜ 0.05].The E value of Group A1 was (9.1± 2.2) mSv ,significantly higher than that of A2 [( 8.1 ± 1.9) mSv,t = 2.7,P ＜ 0.05].Conclusion Application of the MinDose technique not only reduces the radiation dose to the patient,but also meets the requirement of diagnosis.

Objective To study the clinical applications of SIVP detecting hepatocarcinoma in cirrhosis.Methods 40 cases of cirrhosis combined with hepatocarcinoma diagnosed by operation and pathology were collected.Control group were scaned with conventional technique,experimental group were scaned with SIVP.Results Only 5 cases catched the optimal scan timing in control group,the accuracy of diagnosis in hepatocarcinoma was 70%;All the cases found the optimal scan timing in experimental group,the detectable rate of hepatocarcinoma was 95%.Conclusion SIVP can find out the optimal timing,which greatly improved accuracy of diagnosing hepatocarcinoma in cirrhosis.

Objective To analysis the CT features and differential points of adrenal myelolipoma.Methods The CT and clinical information of 9 adrenal myelolipomas were collected.Results CT diagnosed 8 cases of adrenal myelolipoma except 1 case misdiagnosing as adenoma.All mass measuring 2.8～10.5 cm in diameter with clear edge,low attenuation value of fat and irregular linear shadow of soft tissure might be seen in mass.Conclusion CT is the best examination of diagnosing,which could show the position,component of the mass and organs around it.

Objective To analysis diagnostic CT findings of adrenocortical carcinoma.Methods To collect 13 adrenocortical carcinomas verified by operation and pathology from 1990 to 1999.Results 8 cases were functional tumor and 5 were non-function mass.The diameter of 10 cases was more than 5 centimeters.The density of carcinoma was not equality and necrosis was often be found.The edge of 6 cases were clear and 7 were not clear,3 cases had local invade and metastasis.Conclusion CT can diagnose most of functional adrenocortical carcinoma with clinic syndrome but can not differentiate non-function adrenocortical carcinoma from pheochromocytoma.

Objective To investigate the methods and the value of computer virus prevention in picture archiving and communication system(PACS).Methods By establishing a safe and sound management system which employed both hardware and software preventive measures,and strengthening security awareness in personnel,virus infection in PACS was prevented.Results A marked improvement compared to previous network environment was achieved and the virus infection rate reduced by 80%,that were ensuring secure and stable operations of PACS served accurately and efficiently for hospitals and departments.Conclusion Security measures discussed above are effective in preventing computer virus in local area network systems.

Objective To analysis the CT features in 7cases of rare adrenal interstitial tissue tumors.Methods 7 cases of rare adrenal interstitial tissue tumors were verified with operation and histology.2 cases were cyst and 2 were lipoma,neurofibroma,neurilemoma and mesenchymoma was 1 case,respctively.Results Adrenal cyst and lipoma appered the density of water and fat.neurofibroma and neuriemoma were slightly low density mass,without enhancement.There were cystic lesion in neurilemoma.Mesenchymoma had slight or moderate enhancement.Conclusion It is difficult or impossible to distinguish nuerofibroma,neurilemoma or mesenchymoma from non-function adenoma or pheochromocytoma except adrenal cyst and lipoma.

Objective To investigate the possibility to create versatile system recovery disc for PACS workstation using the software Ghost 11. Methods Firstly, PACS and Windows software was installed into a PACS workstation. Secondly, S&R&S V9.7 1112F intelligent system -packaging tool and DllCacheManager_V1.6 Dllcache backup -restore tool were used to package the system. Finally, Ghost 11 was adopted to produce mirror image of the system. Results The image could recover system easily. Conclusion The system-recovery disc created by Ghost11 can significantly minimized the workload when the PACS workstation runs into error and improves the maintenance efficiency.

Objective To study how to finish radiography work satisfactorily under emergency situations. Methods Analyses and sum-up were performed from three aspects, including X -ray diagnostic vehicle, radiography and PTSD. Results The vehicle-mounted X-ray machine was kept good state during high strength utilization. 620 cases from the disaster area were examined and the diagnosing quality was better than usual. Conclusion Such aspects are very important for emergency application of vehicle-mounted X-ray machine as the daily maintenance of the machine, high technical level and proper mental intervention.