ISSN 1004-4140
CN 11-3017/P

2009 Vol. 18, No. 2

CT Theory
The Research on 1D SNMR Inversion by Tikhonov Regularization Method
YU Yong-peng, LI Zhen-yu, GONG Sheng-ping, HUANG Wei, ZHOU Xin
2009, 18(2): 1-8.
The surface nuclear magnetic resonance(SNMR) technology is a method that detecting the underground water directly at surface.After discussing the basic inversion problem, this paper achieve the 1D SNMR Tikhonov regularization inverse by conjugate gradient method.The reliability of the Tikhonov regularization method is illuminated by inversing the theory data, data with the noise and the field data.
Research on the Algorithm of Automatic Detection for Fuze Based on ICT
QIN Xiao-yan, WANG Hai-tao, KONG Wei-wei, ZOU Fei-ping, SHAO Li-kang, DING Hou-ben
2009, 18(2): 9-14.
Aiming at the current problems that the way of fuse detection has low efficiency and requires manual intervention, a new algorithm of automatic detection for fuze based on ICT scanning image is presented.The security states of the fuze can be given by comparing the target region center of gravity for two cross-sectional images.The testing results show that the algorithm presented in this article not only improves the defect of traditional detection methods but also decreases the false alarms rate remarkably.
Spectral Magnitudes of the Sichuan,China,Earthquake of 12 May 2008,and Related Problems
Seweryn J. Duda, Jaromir Jansky
2009, 18(2): 15-23.
The Sichuan earthquake is quantified on the basis of its spectral magnitudes of the P-and of the S-waves.The maximum spectral magnitudes of the two waves are seen to occur at different periods.The tectonophysical significance of the finding is discussed, and it is deduced from it that the S-wave energy radiated during the earthquake was drawn from unusually large volume, if compared to the volume corresponding to the P-waves.The spectral features of the body waves of the Sichuan earthquake are analysed on the background of the spectral features of a selection of worldwide earthquakes.As a result it is concluded that the Sichuan earthquake fits well into the features of the earthquakes in the surrounding regions.
Uncertainties in Seismic Tomography
AN Mei-jian, FENG Mei, ZHAO Lin
2009, 18(2): 24-32.
Seismic tomography is a common geophysical tool to explore three-dimensional deep seismic velocity structure of the Earth.Such deep structures are important information to better understand the Earth.Also, because most surface crustal processes are controlled by deep geodynamic processes, deep Earth structures become more and more favored by many geologists.But because there are currently a lot of seismic tomographic methods and their resulted structures and resolution are different, it is inconvenient for non-seismological researchers to use the tomographic results.To realize a better interdisciplinary combination of geophysics, geochemistry and geology etc., the present study made a comprehensive analysis on possible uncertainties existed in seismic tomographic results.Meanwhile, we gave correspondent suggestions to ensure that geoscientists could envisage the uncertainties and made reasonable use of the tomographic results.
Influence of Geomagnetic Field Variations on SNMR Signal in China
ZHOU Xin, LI Zhen-yu, CHEN Jia-wei, GONG Sheng-ping, HUANG Wei, YUE Kun
2009, 18(2): 33-40.
Surface nuclear magnetic resonance is the only new geophysical method about direct detection of underground water.Obvious effects have been demonstrated in exploration of underground water.However, there are many factors affect SNMR signal, which need research in detail.In this paper, the influence character of the geomagnetic field intensity and inclination on SNMR signal has been discussed and analyzed, and the influence in Chinese region's have been discussed.This paper provides an important reference to hydrological investigation by using SNMR in China.
Resolution Matching Method of High Induction Logging and Applications
GAO Jie, TAN Mao-jin, ZHONG Guang-hai, LIU Huan-li
2009, 18(2): 41-49.
High resolution processing of logs is of great significance to logging formation evaluation in thin beds.Russian High Induction Logging(HIL) tool has been applied in China, but one of main problems is that the resolution of its four curves does not match each other.On the basis of the information compensation theory of the induction logging and the analysis of investigation characteristics of HIL, the method of resolution matching and processing technology have been obtained.The results derived from the assumed formation model and some practical cases show that the resolution matching method is reliable and the processed data in situ is reasonable.
Study of Porosity Distribution Features Using X-Ray CT
GAO Jian, LÜ Jing
2009, 18(2): 50-57.
Recognizing core's porosity distribution feature clearly and characterizing it quantitatively is very important when studying core sample's seepage feature.By scanning dry core and the core saturated with formation water, the porosity distribution features of each scanning slice and the whole core were obtained, and the porosity distribution images of each slice, orthogonal and three dimensional were reconstructed.Statistical features of core porosity distribution could be derived from frequency distribution and cumulative frequency distribution curves of porosity.The level for studying porosity distribution features of core were divided into two levels, 'slice level' and 'core level'.Seven parameters were selected to characterize the central tendency, dispersion and distributional patterns of porosity distribution.It's showed that, the porosity distribution of different scanning slices varied a lot, and core's porosity distribution feature could be characterized well by using the seven parameters.
Industrical CT
Research of Tomography's Application in Multiphase Flow Measurement
CAO Chang-li, ZHAO Wen-cang, YU Xin-bo, YUAN Zhong-xue
2009, 18(2): 58-65.
On the basis of analyzing all kinds of tomography fundamental and its advantage and disadvantage, a new multiphase flow detection technique-an electrical impedance tomography is introduced, and a new algorithm used in EIT image reconstruction is proposed.This algorithm will improve the convergence speed and the quality of the image reconstruction by using the method of mixed genetic algorithm and landweber iteration algorithm.The experimental results show that the EIT system is an effective system for multiphase flow measurement, the algorithm has the advantage of good convergence stability and rapid convergence rate.
A Method of Thresholding Segmentation Based on Histogram
SHAO Li-kang, ZOU Fei-ping, CHI Quan-de, QIN Xiao-yan, DING Hou-ben
2009, 18(2): 66-71.
During the real-time detection fuze based on ICT, the optimal and thresholding segmentation algorithm is quite crucial to the precision of the automatic detection fuze.Based on the feature of the grey histogram from the image, a simple automatic-selected method of thresholding segmentation according to the relation between area ration and the probability of gray-level class is proposed, and the experiment result and analyses is given.
Medical CT
The Effect of Relative Temporal Resolution in Clinical 64-MSCT Coronary Angiography
DU Xiang-ying, LI Kun-cheng, LI Peng-yu, LIU Jia-bin, CAO Li-zhen, YANG Yan-hui
2009, 18(2): 72-78.
Objective:To evaluate the effect of relative temporal resolution on image quality in clinical 64-MSCT coronary angiography and establish the criteria of heart rate selection in coronary CTA.Methods:496 patients who underwent 64-MSCT coronary angiography with approximately normal cardiac function were included in the study.Images from 30% to 80% of cardiac cycle were generated with single sector reconstruction.The images at the vertical portion of the right coronary arteries in single cardiac cycle were used for selection of the cardiac phase with minimal motion artifact, and the heart rate at the cardiac cycle was recorded for calculation of relative temporal resolution.Then the images of the middle portion of right coronary arteries at the best cardiac phase were used for scoring of motion artifacts.We used a term named effective reliability(ER) to describe effective temporal resolution.The relationship between ER and image quality was analyzed to carry out the threshold of ER for different image quality requirements.Groups with acceptable ER and unacceptable ER were compared for the cardiac phase of reconstruction for optimal image quality.Results:Among the 496 patients, heart rates ranged from 43 bpm to 103 bpm.Using the score of 3 as the acceptable image quality, an ER of 81 was considered as the lower limit for successful examination.Using score 4 as the acceptable image quality, an ER of 84 was considered the lower limit.There is significant difference in phase selection between the groups with acceptable ER and unacceptable ER, with more reconstruction in end systole in the group with unacceptable ER.Conclusion:Relative temporal resolution is a critical point for coronary CT.A patient with an ER under the threshold is not a proper candidate for coronary CT imaging.
The Sinus Image of Reduction Dose in Children with Spiral CT
CHENG Ying, CAI Xin-qi, CHEN Jun-bin, JING Yang, GUAN Ji-tian
2009, 18(2): 79-82.
Objective:To reduce radiation dose and ensure sinus image quality in children with optimizing tube current.Materials and Methods:80 children were randomly divided into standard dose group and three low dose groups, in which tube voltage was constantly 120kV and tube current were 350mA, 235mA, 175mA, and125mA, respectively.The mean DLP and ED of each group were measured, compared with mean ED in standard dose group, and then decrease of ED in three low dose groups were calculated separately.The image quality in all groups was blindly evaluated.Results:Compared with standard dose group, ED of other three groups decreased by 23.9%, 42.7%, and 60.2%, respectively.For image quality in all groups, there were no differences found.All sinus images reached desired diagnostic quality.Conclusion:With reduced tube current of 125mA, low dose CT of sinuses in children can yield diagnostic image quality;further radiation dose are reduced about 60%.
The Study to the Multisection Dynamic CT Perfusion on Normal Pancreas
WANG Fang-jun, CHEN Wei-chang, GUO Liang, FANG Xiang-ming, LIU Peng-fei
2009, 18(2): 83-91.
To quantitative analysis and assess the blood perfusion characteristic of normal pancreas by Multisection dynamic CT.To investigate the perfusion parameters's change according to age, sex and difference locations of normal pancreas.30 cases with normal pancreas were examined for pancreatic perfusion and was divided into three sub-group according to age.The multisection dynamic CT perfusion series was performed for pancreatic perfusion on a multisection CT scanner(Siemens somatom Sensation 64), 120 kV, 100 mA.Contrast injection was done by using 50 mL nonionic contrast agent(300 mgI/mL), at a flow rate of 5 mL/s with a power injector, and 6 seconds delay.The data acquisition lasted for 30 seconds.These datas were processed on a SIEMENS workstation using PCT software package, and the mean Fb,Vb,Ttp and PS were measured and statistically analyzed in 30 cases with normal pancreas.The study showed that all perfusion parameters didn't influenced by age, sex and difference locations of pancreas(P>0.05).The mean Fb,Vb,Ttp and PS in normal pancreas tissue were 133.55 ±25.70(mL/100mL/min), 193.78 ±27.01(mL/L), 142.41 ±13.95(0.1 s), 128.72 ±34.53(0.5 mL/100mL/min), respectively.The perfusion parameters in three sub-group according to age were not statistically significant(P>0.05).The mean Fb,Vb,Ttp and PS in pancreas of male were 127.59 ±22.90(mL/100mL/min), 188.72 ±25.19(mL/L), 142.91 ±13.17(0.1 s), 133.30 ±42.86(0.5 mL/100mL/min), respectively and those parameters of female were 142.48 ±28.04(mL/100mL/min), 201.37 ±28.94(mL/L), 141.66 ±15.63(0.1 s), 121.85 ±14.80(0.5 mL/100mL/min), respectively.The perfusion parameters in male and female were not statistically significant(P>0.05).The perfusion parameters in difference locations of pancreas were also not statistically significant(P>0.05).MSCT perfusion imaging may reflect the features of normal pancreatic perfusion.All of perfusion parameters didn't influenced by age, sex and difference positions of pancreas.
Clinical and Imaging Analysis of the Causes of Lumbago-leg Pain
QIU Qi-liang
2009, 18(2): 92-98.
Objective:To analysis of the causes of Lumbago-leg pain,and to explore the roles of imaging modalities for evaluation these diseases.Methods:The clinical and imaging data of one hundred and ninety-eight patients with Lumbago-leg pain were analyzed retrospectively.Results:The positive rate of Lumbago-leg pain is 89.4% by X-ray, CT-positive rate is 96.7%, and there are 144 cases suffered from lumbar intervertebral disc protrusion.Among of 25 cases of negative findings by X-ray and CT, 2 cases of intraspinal tumor, 3 cases of metastases tumor and 8 cases of ankylosing spondylitis were diagnosised by MRI.Conclusion:The causes of Lumbago-leg pain are very complex, and the most common cause is lumbar disc protrusion.X-ray can be used as an necessary technique, MRI should be used as the preferred method, especially in cases of tumor in vertebral canal,if the patients' conditions does not been permitted to MRI, CT can substitute for it, CT scan has higher diagnostic value to the lumbar disc protrusion.
Segmentation of Intracranial Hemorrhage CT Image Based on FCM Clustering Algorithm
WANG Hai-bo, LI Xue-yao
2009, 18(2): 99-105.
To develop a computer aided detection system that improves diagnostic accuracy of intracranial hemorrhage(IH) on brain CT.A novel method for CT image segmentation of brain is proposed, with which, several regions that are suspicious of hemorrhage can be segmented rapidly and effectively.Algorithm of extracting intracranial area was introduced firstly to extract intracranial area.Secondly, FCM was employed twice, we named it with TFCM.FCM was first employed to identify areas of intracranial hemorrhage.Finally, FCM was employed to segment the lesions.Experimental results on real medical images demonstrate the efficiency and effectiveness of the proposed algorithm.
Technology Development of Micro-CT with High Spatial Resolution
GUI Jian-bao, HU Zhan-li, ZHOU Ying, ZHENG Hai-rong
2009, 18(2): 106-116.
Micro-computed tomography(Micro-CT) is a new three-dimension high-resolution imaging device based on X-ray imaging principle.The system enables a non-invasive three-dimensional inspection to the specimen, bones, teeth and biomaterial, and in latest year, it was more widely applied to screen small animal in vivo for drug discovery, cancer pathology and gene expression research.This review describes the technical aspects of Micro-CT, and indicates four main development directions, improved imaging contrast, ultra-high spatial resolution, fast speed and multi-modality imaging.