ISSN 1004-4140
CN 11-3017/P

2011 Vol. 20, No. 4

CT Theory
Far-Field P-Wave Radiation Pattern from ATI Shear Dislocation:Theoretical Studies
CAI Xiao-gang
2011, 20(4): 433-452.
Suppose that source region is ATI medium and propagation path is isotropic media, analytical representations of far-field P-wave displacement and radiation are given and we discuss the effects of source anisotropy on far-field P-wave displacement and focal sphere. Some results show that crack density, azimuth et al. parameters play an important role in P-wave radiation and lead to non-double-earthquake mechanism. We propose that It maybe a good method which we can directly detect percentage of DC, CLVD and ISO for micro-earthquake before large earthquake in the well.
New Seismic Body-Wave Tomography on the Local Scale
HE Rui, ZHANG Yi, YANG Jian-si, ZHANG He-xiang
2011, 20(4): 453-464.
Seismic body-wave tomography on the local scale is a technique of imaging 3-D velocity and/or attenuation structure of the Earth,according to minimum principle of difference between theory arrival time and observe arrival time.Hence,the accuracy of observe arrival time is very important to this technique.In practice,observe arrival time include more or less error,such as artificial error,instrumental error,among which some error is a value which increase with increasing of time.The paper propose a new technique,which can eliminate an effect of the value which increase with increasing of time on the inversion results,and validate the correctness and feasibility of this technique.
Tomography of Seismic P-Waves from Earthquakes and Explosions —Part Ⅱ: Morphology of Faulting of the 2004 Sumatra-Andaman Earthquake from Spectral Seismograms
Monika WILDE-PIÓRKO, Seweryn J.DUDA, Marek GRAD
2011, 20(4): 465-483.
The paper is concerned with the analysis of broadband seismograms of the Sumatra-Andaman earthquake of 26 December 2004. The purpose of the analysis is to recognize the morphology of the faulting process in terms of the time of occurrence and of the frequency content of subevents. The analysis is based on spectral seismograms of P-waves, obtained from the corresponding broadband recordings. It is found that 15 major subevents with maximum radiation intensity at frequencies lower than about 1 Hz occurred during the time window prior to the arrival of the major S-wave. In the same time window however hundreds of subevents took place with maximum radiation intensity at higher frequencies, producing a quasi-continuous "humming" at infrasonic frequencies observable at distances of the order of 8 000 km. In view of the strong absorption of the high frequency waves during the propagation along the ray path, it may be concluded that the "humming" reflects a substantial portion of the seismic energy released during the earthquake.
Mapping the Upper Mantle Discontinuities beneath North China Craton from Common Conversion Points Method with Teleseismic Receiver Functions
WU Yan, DING Zhi-feng, ZHU Lu-pei
2011, 20(4): 485-494.
It is very important to study the structure of upper mantle transition zone to understand the tectonic environment of the lithosphere above.In this paper,we calculate the P receiver functions from the teleseismic events recorded by 35 stations in a line across the North China Craton(NCC),and then mapping the upper mantle structure from the method of common conversion points.The result shows that:the three blocks of the North China Craton stay in different tectonic environment,the western block stay in a stable environment,while the trans-North China oragan in a strong mantle convection circulation environment.The subducted pacific slab under the eastern block formed a relative low temperature under the eastern NCC.So the mantle convection plays an important role in the formation of the Shanxi fault depression zone by contrast with the dextral rotation which is the mainly force of the Huabei fault depression zone.
The Application to Qinhe Dam Hidden Trouble Exploration with High Density Resistivity Tomography Technology
SUN Fang-yu, XU Shun-qiang, LI Qing-lin, GUO Xin-jing, WANG Ning
2011, 20(4): 495-503.
Abstract(1078) PDF(1)
Using the high density electrical method meter,used Schlumberger array to install to the Qinhe river main dike some contract section has carried on the electronic resistivity CT survey.In dam stave,subsidence,crack as well as cavern and so on hidden danger spot even clear reflections.The rivers and streams dam is its basin area people personal safety and property safeguard,is relates the peaceful country and safe people the important matter.Has the important value and the significance to the Qinhe river main dike's hidden danger survey.By the electronic resistivity image formation's method utilization,causes the explanation work to be more convenient and to be direct-viewing,and has the good usability,the validity and the feasibility.
Application of Electrical Resistivity Tomography to the Detection of Buried Faults in Lake Sedimentary Basin: A Case Study in Tonghai Basin
SHEN Kun, ZHU Tao, JIN Zhi-lin, ZHOU Jian-guo, CAI Jian-hua, WU Fu-huan
2011, 20(4): 505-512.
In the present paper,electrical resistivity tomography was used to detect the west branch of Xiaojiang fault in lake sedimentary Tonghai basin.It is found that the location and attitude of this fault could be revealed out only in the deeper part of resistivity tomograms.Our results indicate that this fault has the strike of about N47°E,the apparent dip angle of about 57~66°and the apparent dip direction of NW or W in Tonghai basin,which is almost consistent with previous results.
Industrical CT
Research on Theoretical Estimation of System Performance for 3D X-ray CT with FDK Reconstruction
CAI Dong-shan, SHI Cheng, XING Yu-xiang
2011, 20(4): 513-522.
Since X-ray CT dosage has been pushed to a low level and 3D imaging has been a trend, it is necessary to study the performance of 3D X-ray CT systems. In this work, we firstly propose a theoretical noise estimation method for 3D X-ray CT reconstructions. Then, we present four models for theoretical estimation of system performance for 3D X-ray CT based on FDK algorithm. The theories and analysis are based on Chaimellized Hotelling Observer (CHO). The Difference Of Gaussian (DOG) model is adapted for channels. The theories are validated by different numerical simulations. Our results demonstrate that theoretical estimation method of system performance for 3D X-ray CT accords well with the result from MC simulations. The proposed method for system performance evaluation can exempt us from some of computationally expensive Receiver Operating Character (ROC) studies. It can provide great convenience for system performance prediction and system design optimization. The method is easy to be extended to systems using other linear reconstruction algorithms.
Medical CT
The Comprehensive Analysis of Imaging Diagnosis on Acute Ischemic Cerebrovascular Disease
CHENG Yao-er, HE Wen
2011, 20(4): 523-530.
Objective: To explore the comparative value of CT plain scan,CT cerebral perfusion imaging(CTP),diffusion-weighted imaging(DWI)and MSCT angiography(CTA)in the acute ischemic cerebrovascular disease,and to find a reasonable procedure of imaging examination for acute ischemic cerebrovascular disease.Methods: Examinations of conventional CT,CT cerebral perfusion imaging,diffusion-weighted imaging and MSCT angiography were underwent in 30 cases with acute ischemic cerebrovascular disease.Results: In the 30 cases,plain CT showed the resulting ischemia and infarction in 12 cases.The sensitivity of DWI and CTP for diagnosing acute ischemic cerebrovascular disease were 73.3%,83.3%;The predictive value of positive cases of DWI and CTP were 95.7%,92.6%.Differences in sensitivity and the predictive value of positive cases were not statistically significant among DWI and CTP.CTA demonstrated the involved cerebral arteries for patients of acute ischemic cerebrovascular disease in 27 cases.Conclusion: Conventional CT is the first method of case selection in diagnose in clinic.CTP and DWI are both highly sensitive methods for detecting acute brain ischemia.CTA is helpful in finding the involved cerebral arteries.According to patients'clinical manifestation and economy condition,we cleverly choose these methods.
CT Diagnosis of Neonatal Hypoxic-Ischemic Encephalopathy
HU Yin-song, HOU Zhi-xiong, DENG Jia-xiu, LI Guo-qiang, LAN Hua, HONG Jian-bin
2011, 20(4): 531-535.
Objective: To investigate the clinical value of the CT examination for neonatal hypoxic-ischemic encephalopathy(HIE).Data and Methods: Conduct a retrospective analysis of the clinical data and CT clinic manifestations of 45 cases of neonatal hypoxic-ischemic encephalopathy(HIE).Carry out a confirmation CT scan of the cranial bones and brains of all ill infants within 24 to 72 hours.Results: HIE is categorized into three levels:slight,medium and severe according to CT manifestations(slight,10 cases;medium,20 cases;severe,15 cases;male,26 cases,female,19 cases).Conclusions: CT examination can provide an objective basis for a clinic diagnosis,treatment and assessment of prognosis of the HIE.
Research of DSCT Neck CTA Optimizing Program
CHEN Xin, ZHOU Zhang-sheng, ZHANG Jun, GU Hai-feng, LUO Song, ZHENG Ling
2011, 20(4): 537-544.
Abstract(1085) PDF(0)
Objective: To explore optimal program of dual-source CT in cervical vessel.Methods: 60 Neck CTA cases were randomly divided into two groups(A and B,each group contains 30 cases).The injection rate of contrast is 4.0 mL/s.With the help of automatic trigger technic taking triggered threshold as 120 Hu scanning began4 seconds after the CT value arriving at the peak 75 Hu peak While scanning direction was from caudal to cranial in A group,and cranial to caudal in group B,which is the optimal program.The other parameters were constant.All data was sent to the workstation and evaluated by SIEMENS software.Results: The CT value of brachiocephalic veininjected between group A and B had statistical significance(P<0.01).Although the CT value of aortic artery in group B was a bit higher than that in group A,and the CT value of middle cerebral artery in group B was a bit lower than that in group A,those had no statistical significance.Conclusion: The optimal program of dual-source CT in cervical vessel can effectively demolish the disturbance of brachiocephalic vein injected and improve the image quality of cervical artery.
The Application of Multi-Slice CT Angiography in Diagnosis of Intracranial Aneurysm
XIONG Ju-xin, WU Cai-yun
2011, 20(4): 545-550.
Objective: To evaluate the application values of multislice CT angiography(MSCTA)in the diagnosis of cerebral aneurysms.Materials and Methods MSCTA were performed in 31 patients with cerebral aneurysms confirmed by DSA or operation.CTA were processed with maximum intensity projection(MIP),volume rendering(VR)and curved planar reformation(CPR).20 patients were performed operation and 11 patients were performed operation.Results: 36 cerebral aneurysms were found in 31 patients.29 cases were solitary and 2 cases were multiple(5 cerebral aneurysms).33 cerebral aneurysms were found in MSCTA,but 1 was misdiagnosed.32 cerebral aneurysms were diagnosed correctly by MSCTA,and 4 were missed on the MSCTA.The accurate rate was 97%(32/33)and sensitivity was 89%(32/36).The diameter were between 3~35 mm with average size of 8mm on MSCTA images.The location,size and appearance of cerebral aneurysms showed in MSCTA images were in accordant with the result of DSA and operations.Conclusion: MSCTA can display clearly the location,size and appearance of cerebral aneurysms accurately and objectively.MSCTA and DSA or surgery have high diagnose accordance rate.It plays an important role in the diagnosis of the disease.
Analysis of Imaging Manifest of Desmoplastic Fibromas
WANG Wei, WANG Xiu-ling
2011, 20(4): 551-557.
Objective: To explore the imaging feature of desmoplastic fibromas.Method:To evaluate the pathological origination,clinical presentation and imaging presentation of desmoid tumor in four cases with review of the literature.Result: In the four cases,the lesions has different location.One is in abdominal wall,one is in chest wall and armpit,one is in the underneath of the femur and one is in abdomen.CT and MRI scan demonstrates the desmoid tumor originating from muscle with homogeneous formation.The lesion manifests lower attenuation lump contrasted to the adjacent soft tissue in CT scan and the different components of which lead to various signal in T2WI.After intraveinous contrast material administration,the lesion which has no clear margin always demonstrates inhomogeneous,slight enhancement.Conclusion: Desmoid tumor is an aggressive benign tumor.Because imaging findings have no characteristic,its diagnosis depends on pathological examination.
The Value of 64-MDCT in Diagnosing Perforated Appendicitis
ZOU Jian-hua, ZHENG Qiao
2011, 20(4): 559-563.
Objective: To explore the CT features of perforated and non-perforated appendicitis,and evaluate its diagnostic value. Methods: 24 cases of appendicitis,selected and confirmed by operation and pathology,divided into 2 groups:perforated appendicitis group(10 cases)and non-perforated appendicitis group(14 cases).The CT signs were Analyzed and compared between the two groups.Results: Cellulitis around appendix,appendiceal wall discontinuity and periappendiceal pneumatosis are direct CT signs of perforated appendicitis,diagnosed with a high specificity(P<0.05).Abdominal abscess is confined expression of perforative appendicitis,and peritonitis is its diffuse sign.Indirect signs of CT include appendiceal thickening,wall thickening and strengthening,often combined with intracavitary effusions,bezoar,intestinal effusion,lymphadenopathy and adjacent bowel wall thickening.Conclusion: 64-MDCT is of high diagnostic value on perforated appendicitis.
CT Angiography in Assessment of Arterial Supply of the Femoral Head
YANG Xiu-jun, CHENG Fu-rong, LI Wei
2011, 20(4): 565-571.
Objective: To determine preliminary the values and limits of computed tomographic angiography (CTA)in assessment of arterial supplying to the femur head.Methods: Two thousand and one sets of femoral head thin slice CT axial images in arterial phase were retrospectively 3D reconstructed on AW 4.2 workstation.CTA was obtained by using the 4-detector row CT scanning after single-bolus injection of 95 mL contrast media at 4 mL/s from the peripheral vein.The supply arteries was observed.Results: The CTA sensitivity of MCFA,LCFA and RA were 100%,100%and 28.57%respectively.What were depicted clearly on CTA were their origin,main trunk and proximal portion,and their distal portions were not shown clearly.The method of 3D VR rotation view,using small FOV and minimal value of 75~80 Hu and maximal value of 250~300 Hu,gave good visualization of these vascular structures.Conclusion: It was limited for 4-detector CTA to evaluate the arterial supply of femoral head.
An Analysis of the Development and Present Situation of "CT Theory and Applications"
MAO Guo-min, JIANG Zhi-rui
2011, 20(4): 573-582.
Abstract(1076) PDF(2)
On the basis of data information,a comprehensive statistical analysis is made of the development in recent years and present situation of “CT Theory and Applications”,regarding its subject distribution,internet communication,information of the articles published and quality of the periodical.The analysis reveals the progress made by and problems existing in the periodical.Resultsshow that,in comparison with the periodical itself temporally,it has made remarkable progress,while in comparison with periodicals of the same kind laterally,there is still some way to go,especially in terms of the quantity of articles published.Our results can provide reference for future development and long-term program of the periodical.