ISSN 1004-4140
CN 11-3017/P

2012 Vol. 21, No. 4

Spectral CT
Medipix-based Spectral Micro-CT
Hengyong Yu, Qiong Xu, Peng He, James Bennett, Raja Amir, Bruce Dobbs, MOU Xuan-qin, WEI Biao, Anthony Butler, Phillip Butler, Ge Wang
2012, 21(4): 583-596.
Since Hounsfield's Nobel Prize winning breakthrough decades ago, X-ray CT has been widely applied in the clinical and preclinical applications-producing a huge number of tomographic gray-scale images. However, these images are often insufficient to distinguish crucial differences needed for diagnosis. They have poor soft tissue contrast due to inherent photon-count issues, involving high radiation dose. By physics, the X-ray spectrum is polychromatic, and it is now feasible to obtain multi-energy, spectral, or true-color, CT images. Such spectral images promise powerful new diagnostic information. The emerging Medipix technology promises energy-sensitive, high-resolution, accurate and rapid X-ray detection. In this paper, we will review the recent progress of Medipix-based spectral micro-CT with the emphasis on the results obtained by our team. It includes the state-of-the-art Medipix detector, the system and method of a commercial MARS (Medipix All Resolution System) spectral micro-CT, and the design and color diffusion of a hybrid spectral micro-CT.
CT Theory
Model-guided Iterative Reconstruction for Limited-angle CT Image
HONG Wei, CHU Ying, MOU Xuan-qin
2012, 21(4): 597-604.
Aiming at the problem of limited-angle projection CT reconstruction, a model-guided iterative reconstruction for limit-angle CT image is proposed in this paper. An initial reconstructed image is firstly gained by statistical iterative algorithm from limited-angle data. The initial reconstructed image is fused with a prior-model image to acquire a fusion image. The fusion image is projected again to acquire the complementary projections, on which are the intermediate results of the reconstruction. This projection, fusion and reconstruction processes repeat until the final satisfactory image reconstructed. Simulation results have shown that the object can be reconstructed integrally by the proposed method and the quality of the final reconstructed images increase significantly, with all characteristics of the object preserved.
An Initial Contour Method for Active Contour Model
LÜ Zheng-dong, LIU Run-hua, LÜ Xin-rong
2012, 21(4): 605-614.
Image segmentation which is the basis of image analysis and image understanding is a very important step in the area of image processing. The result of image segmentation determines whether it is suitable to go on the following processing. Considering the defect of the existing image segmentation method such as the slow speed of segmentation and acquiring more manual operations in the area of medical image segmentation, a new method of setting initial contour is proposed in this paper. Firstly the image will be processed simply in which a rough and continuous contour will be obtained, then 8-adjacent segmentation method will be adopted to detect the edge, finally the initial contour will converge to the boundary needed by using gradient vector flow field. Experimental results show that, this method can get a better result of convergence of the target boundary, and is an ideal method for medical image segmentation with fast speed and high degree of automation.
Teleseismic P Wave Tomography on the Crustal and Upper Mantle Structure in Cangzhou Area
LIU Hong-jun, DING Zhi-feng
2012, 21(4): 615-623.
We used 2308 P wave arrival times from 271 teleseismic events recorded by the 20 portable seismic stations during December 2006 to July 2010 in Cangzhou region, Hebei Province. By using seismic tomography method, we got the 3-D crustal and upper mantle P wave velocity structure in Cangzhou and its adjacent area (38.0°N~39.0°N, 116.5°E~117.5°E). Teleseismic tomography results reveal that the significant lateral variations for the velocity distributions in crust on both sides of Cangdong fault zone. The shallow velocity distribution is consistent with the distribution of the surface geological structure. Cangxian uplift in the northwest of Cangdong fault zone is with the higher velocity values in the crust, indicating that it has the uplift basement. Huanghua depression in the southeast of the fault zone is with lower velocity, indicating the substrate buried deeper. These results and previous gravity, electromagnetic and artificial seismic exploration results all show that the Cangdong fault zone is in obvious changes in the geological structure and geophysical properties, which could be displayed in whole crust.
Research of Using Information Fusion Technology to Integrate Seismic Decomposition Spectrum Signals and its Application
CAO Xiang-yang, ZHANG Jin-miao, HAN Wen-ming, XIAO Zhi-bo
2012, 21(4): 625-633.
On the application effect and limitation analysis of RGB frequency mixing display technology which used to integrate decomposed spectrum signals, a new method based on the three parameters wavelet spectral imaging technology and information fusion technology is proposed to predict the geologic abnormal body space distribution. Firstly, basic wavelet is constructed by three kinds of parameters and used to transform seismic signal to get different frequency domains signals, then we integrate those signals with information fusion algorithm based on fuzzy logic theory, The finally result describes geology phenomenon more efficiently like a probability index, The actual data and application effect proved the effectiveness and practicability of this method.
Using CT Imaging between Hole on the Karst Rock Mass Structure and Power Station Dam Foundation Seepage and Stability Research
LI Hua-qing, GAN Fu-ping, WEI Yu, HUANG Xian-bo, LU Cai-kun
2012, 21(4): 635-645.
hydropower station dam Foundation rock of karst caves, karst fracture zone and tectonic development of broken rock such as defect control, prone to subsidence, leakage, resulting in power plant engineering deformation and instability. Karst development and structural change of carbonate rock is very closely connected, therefore, accurate diagnosis of the hydroelectric power station dam Foundation rock mass defect was significant. This use of perspective and CT Imaging of electromagnetic wave between holes, underground concealed carbonate rock structures in non-uniformity, corrosion crack belt interface, fractured structure, nature of crack filler and geometric spatial form for digital descriptions and characterizations. Combined with a hydropower station dam Foundation in Guangxi natural properties of carbonate rock structures, changing characteristics of rock mass structure of the measured data, further analysis in engineering under the action of stress distribution, deformation law of rock, forecast and found seepage of dam Foundation and stability and thus reasonable to develop effective treatment measures.
The Physical Experiment Research in Laboratory of Cross-hole Electric Resistivity Tomography for Detecting Boulders
WANG Jun-chao, SHI Xue-ming, WAN Fang-fang, XU Zi-dong
2012, 21(4): 647-657.
Using the WDJD-3 multi-functional digital DC instrument produced by Chongqing Bunting Digital Control Technical Institute, we design the observing system of cross-hole resistivity tomography to detect boulders in the laboratory, and take series of physical simulation experiments. Many arrays(cross-hole pole-pole, pole-bipole and bipole-bipole) are used in physical simulation experiments. The collected data is inversed by RES2DINV software and we get the following conclusions:(1) imaging results of pole-pole can't reflect the position and size of high resistance body; (2) both imaging results of pole-dipole and dipole-dipole in standalone mode can clearly reflect the position and size of the high resistance body. The results of physical simulation experiments indicate that cross-hole resistivity tomography can be used to detect high-impedance body. The survey method is flexible acquisition, obtaining stable and reliable data, setting clear visual image maps. The result of physical simulation experiment has a positive significance in detecting boulders in the hole of subway tunnel with cross-hole resistivity tomography. Three-dimensional resistivity tomography experiment in detecting boulder is in further studying.
Analysis of Application Effect in Cavity Exploration by Electromagnetic Computerized Tomography
2012, 21(4): 659-666.
The exploration of solution cavity is essential in the construction of pile foundation that results from the solution cavity and crack. Traditional method of solution cavity exploration is mainly based on resistivity method. However, depth is limited and boundary of solution cavity can't be obtained in this method. Additionally, drilling method can only explorer the karst cavity in an infinitesimal area. Electromagnetic Wave Computer Tomography (EWCT) is a developing geophysical method based on characteristics of spreading of electromagnetic wave in different medium. This paper mainly aims to substantiate the effect of karst cavity exploration with the method of EWCT. Result obtained by EWCT has been compared with kinescope and drilling data in an exploration of karst cavity in a huge bridge foundation. The result shows that EWCT is an effective method for karst cavity exploration.
Joint Expioration of EH4 System and Dual-frequency I.P Sounding in Luoning County Xiqinggangping Gold Fielde
CHEN An-wen, MENG Fei, GAO Huan, LI Qing-lin, XIE Ru-yi, LIU Zun-sheng
2012, 21(4): 667-675.
The use of advanced geophysical exploration methods (profile sexual audio-frequency magnetotelluric sounding (AMT) and shock electrical sounding) in gold exploration area detection, the initial identification of mining area of the mainland, thickness, fracture distribution and mineral of IP anomalies electricity, found that concealed the mineralized alteration belt and extending down. Through the analysis of geophysical anomalies and ore (change) body relation, which for deep gold and other non-ferrous metal ore body, gold ore exploration area of the controlled, find out altered with roughly mining area number, distribution, size, shape, form in etc, for the next step exploration engineering arrangement provides the basis.
Industrical CT
Comparative Analysis of Reconstruction Algorithms for Multi-slice Clinical CT
ZHENG Jian, YU Hang, KUAI Duo-jie, LIU Zhao-bang, DONG Yue-fang, ZHANG Tao
2012, 21(4): 677-687.
Currently, there are major Feldkamp-Davis-Kress (FDK) based three dimensional filtered back projection (FBP) algorithms and fan-to-parallel rebinning followed by two dimensional FBP algorithms for multi-slice clinical CT reconstruction. This paper compared four different reconstruction algorithms, including conventional FDK algorithm, two-dimensional-weighted cone beam filtered back projection (CB-FBP) algorithm, three-dimensional-weighted CB-FBP algorithm and adaptive axial interpolator (AAI-FBP) algorithm. We performed a experiment on simulated helical projection data of Shepp-Logan phantom. After that, a detailed comparative performance analysis of the four algorithms is given. Conclusion:we find that AAI-FBP might be the optimal choice for conventional multi-slice clinical CT reconstruction. We hope this paper could be helpful for the improvement of multi-slice CT reconstruction algorithm as well as clinical application research.
An Adaptive Regularization Iterative Reconstruction Algorithm on the Basis of a Sparse Constraint
WANG Chao, YAN Bin, LI Lei, ZENG Lei, LI Jian-xin
2012, 21(4): 689-698.
In this paper, the constraints on Weighting of ASD-POCS (Adaptive Steepest Descent-Projection Onto Convex Sets, ASD-POCS) algorithm weight caused by the variability of different applications, algorithm robustness and poor. It proposes an adaptive regularization iterative reconstruction algorithm on the basis of a sparse constraint: the AR-SART-CG (Adaptive Regularization-Simultaneous Algebraic Reconstruction Techniques-Conjugate Gradient, AR-SART-CG) algorithm. The algorithm adopts a kind of Lagendijk type of Regularization Strategy to construct optimization, respectively uses local variance, noise estimation, and image energy estimation to adaptively adjust the parameters weighted diagonal matrix and global regularization, and respectively applies SART algorithm and conjugate gradient method to solve optimizations of fidelity term and constraint term. Since that the algorithm can adaptively adjust the weight of constraints, it is possessed of strong robustness. The experimental results show that the AR-SART-CG algorithm can better balance and preserve the relations between picture edge and smooth noise.
Development and Application Analysis of a Tester for X-ray Detectors
HUO Mei-chun, DONG Guo-ping, LIANG Ze, LI Hao, LIU Dan, GU Dong-bo, MIAO Xiang-yue
2012, 21(4): 699-704.
The X-ray detector tester is an essential testing device for testing the performance indexes of the linear array X-ray detector, the core component of X-ray security inspection equipment, such as signal gain, background noise signal, and signal crosstalk of adjacent pixels. Its function and key techniques are briefly discussed in this article. And a manual fine tuning tester for X-ray detectors design and manufactured by us is mostly introduced in this article. Moreover, its partial test results to some X-ray detectors are given and analyzed.
A Method on X-ray Security Image Enhancement
YANG Xiao-gang, YANG Li-rui
2012, 21(4): 705-712.
This paper proposes a new method for image enhancement of an X-ray screening image. Generally speaking, Image contrast of X-ray screening is smaller, the edge is not clear enough and noise of these image is unacceptable. the idea of this method is as follows:first, removing the noise of the background area of the security image, second, using the Laplace transform on the edge of the image,third, enhancing image contrast by CLAHE (local constrained histogram equalization), finally, using the bilateral filter to reduce image noise under the premise of maintaining the image edge. Such a combination method is perfect to correspond well to the characteristics of the traditional X-ray security screening images.
Medical CT
Preliminary Study on CT Urography and Angiography (CTUA) in One Acquisition
QIAN Yan, YANG Xiu-jun, CHENG Fu-rong, TANG Lei-hua
2012, 21(4): 713-719.
Objective:To determine preliminarily the feasibility and a one-stop strategy of CT urography and angiography in one scanning acquisition using 4-slice MDCT. Materials and methods:Seventy-five consecutive patients (41 men and 34 women; mean age 52 years; age range, 22 to 86 years) without evident hydronephrosis who asked for CT urography (CTU) examination received the new technique of CTUA using by 4-MDCT. Twice-bolus protocol consisted of 50 mL of contrast material (300 mg per milliliter of iodine) immediately after urinating at 2~2.5 mL/sec at 0 seconds and 50 mL at 3.5~4 mL/sec at 20 minutes through the forearm vein. CT scanning (CTUA) started with one breath-hold 20 seconds after the second injection with 10 mm of slice thick, 0.75:1 of pitch and 15 mm/rot of speed. Five minutes after the second injection, CT scanning started again using the same parameters for routine CTU. After thin-slice reconstruction of 5 mm thick and 2.5 mm interval, all the images data were then transferred to an ADW 4.2 workstation to post-process by 3D VR software. Excellent rate of visualization of renal parenchyma, urinary tracts, and main arteries on CTUA and CTU images were reviewed and assessed independently first and interpreted agreeably by two experienced radiologists. Statistical analysis was performed using variance analysis (ANOVA) to evaluate the difference, and P<0.05 is considered statistically significant. Results:The technique success rate of CTUA was 100%, and excretory-corticomedullary phase source images were acquired, which the good rate of distinguishing the renal cortex from the medulla and calices was 100% (148/148), while the CTU source images were not well depicted the renal cortex, medulla and calicessimultaneously (P=0.000). The good opacification of the renal calices, ureter, bladder, and the renal artery, the aorta and iliac artery was achieved in 95.94% (142/148), 94.59% (140/148), 95.95% (71/74), and 87.16% (129/148), 96% (72/75), 81.33% (122/150) of segments, respectively in CTUA, and 100% (148/148), 97.97% (145/148), 98.65% (73/74), 0%, 0%, 0% of segments, respectively in CTU. Urinary tracts were shown slightly better in CTU than in CTUA (P>0.05), but the arteries were shown significantly better in CTUA than in CTU (P=0.000), and the CTUA could accurately reveal the tumor, stones, inflammation, prostatic hyperplasia, atherosclerosis and all kinds of deformities of urinary tract and vessels. Conclusion:It is technically adequate for a one-stop CTUA to achieve by using a single excretory-corticomedullary phase CT scanning after twice-bolus contrast injection with routine concentration and volume with once venepuncture. It three-dimensionally reveals renal parenchyma, urinary tract and main arteries simultaneously and the renal cortex, medulla and calices are also distinguished clearly.
The Application of “Magic Glass” Function in Coronary CTA
TIAN Shu-ping, YANG Li, WANG Zhan-yu, WANG Shou-hai, WANG Zi-jun, ZHANG Yan-qun
2012, 21(4): 721-726.
Objective:To explore the clinical application value of "Magic Glass" function in coronary CTA. Methods:A retrospective analysis of 50 hospital cases of coronary CTA was used to evaluate the value of "Magic Glass" function application in the coronary plaque, luminal conditions and assessment of coronary stent. Results:All 50 cases of coronary CTA images can be used for diagnosis. After application of "Magic Glass" function, 595 calcified plaque, 1290 mixed plaque, 126 non-calcified plaque was found; and lumen of 729 CA segments was clearly showed; stenosis 75%, 146 segments, 50%~75%, 209 segments, 25%~50%, 108 segments, 25%, 266 segments. 11 of 29 implanted stents, lumen formation of soft plaque, stenosis 5, 6 plaque formation before and after stent, causing stenosis 4. Conclusion:The application of "Magic Glass" function in coronary CTA reconstruction can clearly display and evaluation of coronary artery plaque, coronary stent lumen conditions, and does not affect the outside organization of "Magic Glass".
The Imaging Findings of Neuropathic Joint Disease Associated with Chiari Disease
DING Chang-qing, SUN Ying-ying, ZHANG Yu-na, WANG Wen-sheng, WANG Chen
2012, 21(4): 727-734.
Objective:To analyze the imaging findings of neuropathic joint disease caused by Chiari disease. Methods:The imaging data of 8 cases of neuropathic joint disease caused by Chiari disease were retrospectively analyzed. Results:All were Chiari disease complicated with syringomyelia, of them 3 cases after surgery for Chiari disease. 17 joints were involved, among them the shoulder in 11, the elbow in 6. Hyperplasia type in 7 joints, the imagings expressed as joint osteophyte formation and proliferation. Absorbent type in 10 joints, the imagings showed irregular articular surface of bone fragmentation, dissolution, bone marrow edema, nub presented papercut transformation. Two types could be associated with bone marrow edema (of them five parts involving the backbone), joint loose bodies and joint swelling, effusion. X-ray could show the joint dislocation, osteosclerosis and absorption. 16-slice CT combined with post-processing also could show the position and number of the loose bodies from multi-angle. MRI could accurately diagnose Chiari disease complicated with syringomyelia, the ability for MRI to display backbone edema is superior to X-ray and CT, the ability for water imaging sequence in MRI to show the small loose bodies within the joint effusion is superior to other examination. Conclusion:It is helpful for the diagnosis of neuropathic joint disease by Chiari disease with the combination of X-ray, CT and MRI.
Spiral CT Diagnosis of Acute Pancreatitis Classification Method and its Clinical Significance
YANG Xiao-sheng, CHEN Qin, CHEN Xi-feng
2012, 21(4): 735-740.
Objective:Discussion of 16 slice spiral CT in the diagnosis of acute pancreatitis classification method and its clinical significance. Method:A retrospective analysis of 2009~2011 years of acute pancreatitis in 41 patients, male 23 cases, female 18 cases. All patients underwent CT plain scan and enhanced scan. Result:According to the CT severity index score, CTSI:According to the score will result in turn is divided into 3 grades:Light level (0~3) in 23 cases, accounting for 56.1%, intermediate (4~6) in 7 cases, accounting for 17.1%, heavy (7~10) in 11 cases, accounting for 26.8%. Conclusion:Spiral CT for the diagnosis of acute pancreatitis provides intuitive basis, CTSI not only can accurately reflect the severity of acute pancreatitis, and can accurately judge the severity of acute pancreatitis in early stage and prognosis of acute pancreatitis, clinical treatment and prognostic significance.
Correlation Study on MSCT Manifestation of the Brain Damage and the Clinical Degrees in Neonatal Hypoxic-ischemic Encephalopathy
WANG Ye-qing, ZHUO Guo-ran
2012, 21(4): 741-746.
Objective:To investigate the multi-slice spiral CT (MSCT) manifestation in neonatal hypoxic-ischemic encephalopathy, and help improve awareness of the disease and clinical diagnosis. Methods:The brain MSCT was performed in 63 cases of clinically confirmed HIE.The MSCT manifestation and clinical data were retrospectively analysis. Results:Divide the cases by CT degrees, 33 cases are mild, accounting for 52%, 22 cases are moderate, accounting for 35% 8 cases are severe, accounting for 13%. The brain CT performance of 63 patients were related to newborn's year, checking time and cure. Conclusion:MSCT scan can accurately diagnose the extent of HIE and its complications, MSCT scanning has important significance in finding of brain injury, evolution of prognosis and conduction of therapeutic schemes.
Spiral CT Study on Intravenous Contrast-enhanced Inspection Parameters of the Lower Extremities
ZHAO De-ming, GU Xiao-ying, PEI Lin-hui, CHEN Jie, ZHU Hong-gen, SUN Yong-kang
2012, 21(4): 747-752.
Objective:To study chronic lower limb intravenous contrast-enhanced spiral CT examination of optimal scanning parameters so that the intravenous contrast agent reached by upper limbs lower limbs of intravenous contrast-enhanced spiral CT diagnosis of image effects. Materials and methods:a collection of 400 patients with chronic diseases CT enhanced check information. Which 200 cases experimental group due to long-term upper limb intravenous caused vein vascular injury serious chronic disease people, in for enhanced CT check work in the, take by lower limb vein (feet, and ankle Department vein vascular mainly) injection contrast agent spiral CT enhanced check, injection rate to 2.5~3.3 mL/s, non-ion type contrast agent 70~100 mL, artery period and the vein period under organization organ are more upper limb intravenous contrast agent extended delay time 8~15 seconds, Spiral CT scans include checks organ range, lesions and sweep the thin layer; control group of 200 patients with intravenous contrast-enhanced CT examination of the elbow chronic diseases of upper limb, depending on the tissues and organs of different injection rate, non-ionic contrast dose and spiral CT scanning method and experimental groups are the same, arterial and venous injection contrast set the delay time for the period according to the tissues and organs. Two sets of normal tissue CT image analysis of measurement and pathological tissue CT value and scan curves, and for statistical analysis. The result:Experimental group of 200 cases of lower limb vein (foot, ankle, vein) injection of contrast-enhanced spiral CT examination of cases linked to the control group of 200 cases of intravenous contrast-enhanced CT examination of the elbow in the upper limbs chronic enhanced check image quality similar to the statistical analysis. Upper and lower limbs arterial CT value arterial CT value is matching, the statistics analysis t value is 4.371, P=0.000, think that the two groups there exist significant differences, have a statistics meaning, that is, upper and lower limbs arterial CT value arterial CT value in different ways. Upper limbs vein phase CT value and venous phase CT value matching comparison, t value is 1.664, P=0.103>0.05, think it's the difference between them was not statistically significant, no significant difference, that is, upper limbs vein phase CT value and venous phase CT value difference was not statistically significant, believe that the difference does not exist. Conclusion:Long-term serious chronic diseases caused by intravenous injection of vein injury of upper limbs after intravenous contrast-enhanced scan of lower extremity take appropriate scans can increase latency time achieved quality of intravenous contrast-enhanced spiral CT scan of upper extremity.
Application Study of Low-dose 128-Slice Spiral CT Coronary Artery Angiography
ZHANG Chao-liang, GUAN Yu-bao, LIN Han-fei, CHEN Huai, ZENG Qing-si
2012, 21(4): 753-759.
Objective:To evaluate the value of low-dose scanning with 128-slice CT coronary artery angiography. Methods:120 patients, heart rate<80 bpm, regular rhythm, were randomly divided into two groups. The first group was 60 patients with low-dose (100 kV) scanning, the second group was 60 patients with conventional dose (120 kV) scanning. Volume computed tomography dose index (CTDIvol) and dose-length product (DLP) were automatically obtained by CT scanning, and effective dose (ED) were obtained by calculating. Two associate chief physicians review the CT images independently. Two groups were evaluated for image quality score (10 segments, each coronary artery segment, 4-point scale) and radiation dose, A p value below 0.05 was considered statistically significant. Results:The mean CTDIvol for the first group was 11.35 mGy ±1.2 mGy, the mean ED was 2.62 mSv ±1.4 mSv, and the mean CTDIvol for the second group was 22.82 mGy ±2.3 mGy, the mean ED was 5.27 mSv ±2.0 mSv, The ratio of CTDIvol and DLP for two groups were 49.7%, 49.7% respectively, the two groups difference were statistically significant (P<0.05).The mean image quality score for two groups were not statistically significant (P>0.05). Conclusion:Low-dose scanning of 128-slice spiral CT can maintain highest image quality while reducing the radiation dose (100 kV) in coronary artery angiography. This technique is suitable for promote in clinical.