CT理论与应用研究

Analysis of Scattering in Triple-source Cone-beam CT Based on Monte Carlo Method

YANG Zhen-yu, LÜ Yang, ZHAO Jun

2012, 21(1): 1-9.

Abstract(1474) PDF(1)

Abstract:
The scattering has serious influence on the image quality in X-ray CT.Multi-source CT is a trend of future CT system since it can significantly improve the temporal resolution.However, as the number of sources increases, more scattered radiation will occur.The scattering issue should be taken into consideration in the practical applications.A CT simulation software, SimProj, has been developed based on the open source tool EGSnrc to generate cone-beam projections which approach the real data.Reconstructed images from the simulated data show scattering induced artifacts as expected.The analysis results are important and helpful for the optimization of designing and manufacturing of triple-source cone-beam CT.

A Method for the Local Reconstruction of Flat Object Based on FDK Algorithm

WANG Xian-chao, WANG Lin-yuan, LI Lei, YAN Bin

2012, 21(1): 11-18.

Abstract(1364) PDF(3)

Abstract:
The local reconstruction with truncated projection data is a difficult problem in CT reconstruction field.Conventional reconstruction algorithms will product severe truncated artifacts.The rising BPF algorithm and POCS iterative algorithm can solve the local reconstruction problem,but their reconstruction efficiency and paralleling performance are poor.In this paper,aiming at special structural flat object,it is found that if the thickness and the horizontal length of local area satisfy some conditions,accurate reconstruction can be carried out using efficient FDK algorithm.The results of numerical experiments show that when the horizontal length of local region is bigger than 1/8 horizontal length of object and the thickness is less than 1/13 horizontal length of object,the reconstruction results are comparable with the true values.The reconstruction results of real data also confirmed FDK algorithm could reconstruct the local area of flat object well under the condition.

Model Experiment for Reflection and Refraction Velocity CT of Natural Earthquake

CHEN Li-cheng, TANG Tang, WU Fa-en, WANG Li-chun, FENG Guo-chen

2012, 21(1): 19-26.

Abstract(1211) PDF(1)

Abstract:
Base on the theory established in which deal with the man-made multilayer medium data,we apply it to the case of natural earthquake by using the principle of minimization of travel time and tomography of fundamental solution of wave equation to invert the interface shape and the velocity of P and S seismic wave’s velocity of each layer.

Study of Method in Core Analysis by NMRI

LANG Dong-jiang, LÜ Cheng-yuan, LUN Zeng-min, SHANG Gen-hua, PAN Wei-yi

2012, 21(1): 27-35.

Abstract(1553) PDF(0)

Abstract:
Study of method in core analysis by MRI and Image processing technology.Principle of NMR imaging and Image processing function are described.Through the study of testing rock and math method,and established the methods to analysis formation structure,porosity and porosity distribution image,permeability and permeability distribution image,movable fluid percentage image,identification of water and oil image.The results indicated that testing rock by using MRI technology not only determine porosity and permeability parameter,but observe porosity and permeability distribution image also.Movable fluid in rock is observed by movable fluid percentage image.The method of identification of water and oil give distribution of water and oil in rock,oil and water saturation is calculated.Method in core analysis by MRI can apply to reservoir evaluation,development, experiment,enhance recovery ratio research in oil field.

Defects Location Method of CT Image Based on Similarity Transformation

YU Guang-hui, LU Hong-yi, ZHU Min, WANG Xing-bo, WANG Hong-ling

2012, 21(1): 37-42.

Abstract(1220) PDF(2)

Abstract:
In order to locate the defects in CT image simply and effectively,a new method base similarity transformation was put forward. The defect location of CT image is got by the method on basis of similarity transformation properties put forward and proved.The effectiveness and accuracy of the method turned out by was put forward.The defect location of CT image is go analysis on location result.The feasibility of artificial template is drawn from comparison between different location results got by different templates.

Weld Defect Classification and Recognition of the In-service Pipeline Based on BP Neural Network

WANG Dao-kuo

2012, 21(1): 43-52.

Abstract(1195) PDF(2)

Abstract:
This paper utilizes the computer to assist in the weld defect detection of the in-service pipeline,in the defect feature,degree of circularity,length-width ratio,compactedness,sharpness of the nose,degree of symmetry、gray scale ratio and the position of the defect’s barycentric coordinates relative to weld center etc.seven parameters are extracted as defect feature,so that different fault defect can be classified and recognized.In the solution of the defect classification and recognition,this paper adopts the self-organized and self-adaptive-3 layers back propagation neural network,applies modified BP algorithm,and takes weld defect feature parameters as training sample of neural network.The network’s hidden nodes number,momentum coefficient,error level and step length etc.network parameters can be obtained optimum values by experimental method.Finally,weld defect classification and recognition achieved effectively.

Extraction of ROI from CT Liver Based on Entropy Image Segmention Algorithm

LI Ling, YE Hua-shan, YU Hou-qiang

2012, 21(1): 53-60.

Abstract(1167) PDF(1)

Abstract:
Objective: In the computer-aided diagnosis and treatment of the future,in order to extract a good CT liver tissue has been divided in the interest area.Methods: Using entropy segmentation algorithm for CT liver tissue region of interest of automatic segmentation,and professional doctor’s manual segmentation in the zone of interest relative ratio.Results: Segmentation of the region of interest and specialty physician’s segmentation of the region of interest,with good access to the capacity of region of interest.Conclusion: In different conditions of the liver to do the corresponding pretreatment,and then the manual segmentation of the region of interest and entropy in the corresponding data for comparison,the entropy method is very effective.

Location of Pulmonary Tuberculosis in CT Pulmonary Images

YILIYAER Dawut, HALIDAN A

2012, 21(1): 61-65.

Abstract(1531) PDF(0)

Abstract:
With the rapid development of medical image processing,the locating methods of lesions in the medical applications attract more and more people's attention.With CT images as the research object,in view of the pulmonary tuberculosis of positioning.This method first made the preprocessed image a binary one,and employed morphology techniques to get rid of small bridges,then labeled every connectivity component in that binary image respectively.Finally through the decision-making device which including the area,perimeter,location parameters,shape parameters characteristics to judge the tuberculosis and locate the lesions area.

Low Dose 64-slice CT Coronary Angiography with Retrospective ECG Gating: A Clinical Study

GAO Jie, ZHANG Xue-feng

2012, 21(1): 67-72.

Abstract(1251) PDF(0)

Abstract:
Objective: To compare image quality and radiation dose for coronary artery computed tomographic angiograms(CTA) with retrospectively gated helical(RGH) CT technique in two methods using 64-slice spiral CT.Methods: 80 patients with low heart rate enrolled in this study were randomly divided into two groups.The low dose RGH group was 40 patients with average body mass index(BMI) 27.06 using ECG modulation technique(full mA on 70%~80% of the R-R interval and the lowest mA on rest of phases).The traditional RGH group was 40 patients with BMI 25.66 using ECG modulation technique(full mA on 35%~80% of the R-R interval and the lowest mA on rest of phases).Two groups were evaluated for image quality(each coronary artery segment,5-point scale) and radiation dose and compared with image quality score and radiation dose by Mann-Whitney U-test and unpaired t-test.A p value below 0.05 was considered statistically significant.Results: The mean effective dose for the low dose RGH group was 13.76 mSv;this represents a 31.40% reduction as compared with that for the traditional RGH group(mean,20.06 mSv;t=-8.391,P=0.00).The mean image quality score was 4.05 for images obtained with low dose ECG modulation technique versus 4.19 for images obtained with traditional ECG modulation technique(Z=-4.78,P=0.23).Conclusion: RGH coronary CT angiography using ECG modulation technique(full mA on 70%~80% of the R-R interval and the lowest mA on rest of phases) could offer assessable image quality and substantially reduced effective radiation dose compared with traditional RGH coronary CT angiography at low heart rate.

MSCT Manifestations Analysis and Diagnostic Value of Retroperitoneal Stromal Tumors

LI Xiao-li, KOU Wen-chao, CHEN Ping-you

2012, 21(1): 73-80.

Abstract(1522) PDF(0)

Abstract:
Objective: To analyze the Clinical and pathological characteristics and MSCT manifestations of retroperitoneal stromal tumors,and investigate diagnostic value of MSCT for retroperitoneal stromal tumors.Methods: The clinical and CT date of 12 patients with retroperitoneal stromal tumors confirmed by operation and pathology were retrospectively reviewed.All patients underwent plain CT scans and contrast–enhanced CT scans before operation.Results: Among the 12 patients,7 were men and 5 were women,the ages ranged above 40 years old in 8 cases,mean age 55 years old.The major clinical symptom of the retroperitoneal stromal tumors were abdominal masses and bellyache.12 patients of retroperitoneal stromal tumors on CT showed retroperitoneal soft tissue masses,the biggest diameter of tumors ranged from 3.0 cm to 21.0 cm,mean 11.0 cm.The tumors were round or oval in 7 cases,irregular in 5cases.The tumors in 2 cases were uniform density on plain CT scans,1 case of uniform enhancement and 1 case of non-uniform linear enhancement on contrast—enhanced CT scans.10 cases showed unhomogeneous density on plain CT scans,low density necrosit in 10,hemorrhage in 2 and calcification in 2;moderate or remarkable enhancement was found in the parenchyma of the tumor,while no enhancement was found in the necrosis and cystic areas of the tumors on contrast—enhanced CT scans.There were benign tumour in 1,potential malignant tumours in 3 and malignant tumours in 8,metastases were found in 3 cases.In 12 cases,all were CD 117 positive,7 were CD 34 positive in immuinohistochemical test.Conclusion: The retroperitoneal stromal tumors usually involve middle-old,and clinical symptom is rare;the CT findings of the retroperitoneal stromal tumors display some characteristic signs and demonstrate the pathological features,which is very helpful in the diagnosis and differential diagnosis.

MSCT One-stop Recombination in Lumbar Disease Diagnosis Application Value

ZHANG Hai-bo, HU Xi-yao, FU Chuan-ming, XU Lin, WANG Kai-hua

2012, 21(1): 81-88.

Abstract(1097) PDF(1)

Abstract:
Objective: To evaluate multi-slice spiral CT(MSCT) in lumbar-stop re-diagnosis of clinical value.Methods: GE's 16-slice spiral CT(Light speed 16) of 50 patients with clinical diagnosis of lumbar disc patients were routine lumbar CT scan and volume scan;in AW4.2 workstation will simulate the CT volume scans regular waist restructuring and one-stop re-scan the disc(including VR,MPR,CPR).The more conventional analog conventional lumbar disc lumbar disc scan and sweep and stop re-restructuring of the lumbar lordosis,lumbar vertebral hyperostosis,intervertebral joint abnormalities,bony spinal stenosis,abnormal transverse and transverse foramen,the vertebral space narrowing,lateral recess stenosis,vertebral Hsu nodules or damage,disc abnormalities,paraspinal soft tissue abnormalities,nerve root compression,the degree of spondylolisthesis,posterior longitudinal ligament and yellow ligament show signs of calcification and other related capabilities.Results: The posterior longitudinal ligament and yellow ligament calcification,nerve root compression,disc abnormalities,intervertebral joint abnormalities,lateral recess stenosis,paraspinal soft tissue abnormalities,abnormal transverse and transverse holes in the conventional analog conventional scan and lumbar disc lumbar disc restructuring and one-stop re-scan on the three good agreement,no significant difference(P>0.05);lumbar lordosis,lumbar vertebral bone hyperplasia,nodules or vertebral destruction Hsu,spondylolisthesis the degree of spinal stenosis in a routine bone scan and simulation of conventional lumbar disc lumbar disc scanning is also on the restructuring has good consistency,but there are significant differences and one-stop restructuring(P<0.05).Conclusion: MSCT volume scan can accurately show the reorganization of one-stop for more images of lumbar spine disease-related signs,for clinical diagnosis of more valuable image information,and reducing the inspection cost and radiation in patients with radiation damage.

Influence of Different Injection Rates of Contrast Medium with 64-slice Helical CT on Effect of Liver Arterial Phase Enhanced Scanning

XIA Zhen-ying, CHEN Feng, LI Hong-jun

2012, 21(1): 89-96.

Abstract(1332) PDF(1)

Abstract:
Objective: To discuss the influence of different injection rates of contrast medium with 64-slice helical CT on effect of liver arterial phase enhanced scanning.Methods: We retrospectively analyzed 80 patients for abdominal CT enhanced scanning.All patients were divided into two groups,the normal group(A group) and the cirrhosis group(B group),each group had 40 cases.According to the injection rate of contrast medium,each group was divided into 2 groups,the 3.5 mL/s group(group A1,B1) and 2.5 mL/s group(group A2,B2).Using Smartprep tracking technology of contrast medium,when the abdominal aorta CT value reached or exceeded 150 Hu,pressed the scan button and began formal scan.Under different injection rate of contrast medium,the peak enhancement of abdominal aorta and trigger time of arterial phase were measured.Recorded good and excellent rats of normal and cirrhotic group,then compared statistical results.Results: When the injection rate of contrast medium was 3.5 mL/s and 2.5 mL/s,The good and excellent rates of normal group was 96.4% and 91.7% respectively,P>0.05,and that of cirrhosis group was 95.5% and 72.2% respectively,P<0.05.When injection rate of contrast medium was 2.5 mL/s,the mean peak enhancement of abdominal aorta in normal and the liver cirrhosis group were 196.40 Hu ±20 Hu and 186.02 Hu ±18 Hu respectively,P>0.05;arterial phase average trigger time of normal group and cirrhosis group was 22 seconds and 24 seconds respectively,P<0.05.When the injection rate of contrast medium was 3.5 mL/s,the mean peak enhancement of abdominal aorta in normal group and cirrhosis group were 244.90 Hu ±37 Hu and 219.33 Hu ±33 Hu respectively,P<0.05;the average trigger time of arterial phase in normal group and the liver cirrhosis group was 20 seconds and 22 seconds respectively,P<0.05.Conclusion: The injection rate of contrast medium is faster,the arterial phase peak is higher,the triggering time is shorter.In the same injection rate,the mean peak enhancement of abdominal aorta of normal group is higher than that of cirrhosis group,and the average trigger time is shorter than that of cirrhosis group.Liver cirrhosis group needs higher speed on injection than normal group.

Improved Imaging in Lumbar Facet Joint Degeneration in the Clinical Understanding

ZHAO Yun, ZHANG Hai-bo, XU Lin, CHEN Lun-gang, WANG Kai-hua, XU Jian

2012, 21(1): 97-104.

Abstract(1149) PDF(0)

Abstract:
Objective: Improved imaging in lumbar facet joint degeneration in clinical understanding.Materials and methods: Retrospective analysis of 80 cases of degenerative lumbar facet joint injury in patients with X-ray,CT,MRI imaging data,in the facet joint bone,proliferation and articular surface flatness,joint space(narrowing,vacuum sign),joint dislocation,facet fracture,yellow ligament calcification,articular cartilage,joint capsule swelling,synovial cyst,synovial cyst hernia in terms of three other shows to compare;and degenerative injuries caused by lumbar spondylolisthesis,the degree in the slip,location,type,diagnosis and surgery on three findings.Results: The result showed that CT displayed more clearly on the sclerotin of small joint axon,articular surface hyperplasia and smoothness,joint space,joint dislocation,joint nonunited fractures and yellow ligament calcification than X-ray and MRI,but MRI play ed a more important role in articular surface cartilage and joint capsule swelling,cyst synovial as well as synovial hernial sac.Besides,X-ray also helped to the articular surface hyperplasia and Joint space narrowed.When it comes to the lumbar spondylolisthesis degrees and positions,the three inspection methods made no differences.Also,CT had an obvious advantage than X-ray and MRI in judging the lumbar spondylolisthesis type accurately while.Conclusion: imaging each have theirown advantages and disadvantages in image diagnosis of lumbar smalljoint degenerative damage.So,we could choose a reasonable examination method by combining with clinical symptoms and signs,offering accurate image information for clinical diagnosis and one of the best treatment plans.

The Application of Whole Body Diffusion Weighted Imaging with Background Body Signal Suppression in the Diagnosis of Thoracic Tumorous Lesions

YIN Xiao-ming, CHANG Xin, DENG Mao-song, DENG Gang, FENG Chen-lu, WANG Meng, ZENG Qing-yu

2012, 21(1): 105-118.

Abstract(1953) PDF(2)

Abstract:
Objective:To evaluate the role of DWIBS in the diagnosis of thoracic tumorous lesions.Materials and Methods:102 cases (patients suspected chest tumors clinically in Beijing Coal General Hospital from 01, 2009 to 12, 2010, total 158 lesions) were involved in this study, including 33 lung cancer, 18 pulmonary benign tumorous lesions, 24 malignant lymphoma, 24 mediastinal and subaxillary lymph node metastasis, 22 breast cancer, 17 breast benign lesions and 20 focal normal breast tissues.All 158 lesions were performed DWIBS (STIR) examination and 33 of them also received DWIBS (SPIR) examination and another 4 cases received thoracic-abdomen-pelvis DWIBS (STIR) scan, then their ADC value were measured and compared.The lesions were displayed by background suppression rebuilding with 3D MIP (3 dimensional maximum intensity projection) and technique with reverse black and white.The ADC values of all lesions were measured.Results: (1) The effect of background suppression of STIR-EPI was better than SE-EPI (SPIR) and could get PET-like images with 3D MIP rebuilding and reverse black and white technique to observe the lesion more clearly. (2) The mean ADC value of thoracic metastatic lymph nodes was 1.37±0.41 mm²/s×10^-3 and 0.91±0.12 mm²/s×10^-3in thoracic lymphoma.There was significant difference between them (P<0.05);The mean ADC value of lung cancer was 1.61±0.18 mm²/×10^-3 and 2.06±0.21 mm²/×10^-3 in pulmonary benign lesions, and it was significantly ower than that of benign lesions. (3) The ADC value of different types of malignant different between the two types of lesions;The mean ADC value of breast cancer, breast benign lesion and normal breast tissue was 1.01±0.13 mm²/×10^-3, 1.81±0.18 mm²/×10^-3 and 1.91±0.26 mm²/×10^-3 respectively, and there was significant difference between either two groups. (3) The ADC values of different types of malignant tumors were significantly different. (4) Among the 4 cases with thoracic-abdomen and pelvis DWIBS examination, 3 cases were with distal metastasis.Conclusions: (1) DWIBS was a safe and effective imaging examination. (2) It benefited to identify the property of the thoracic tumorous lesion that was benign or malignant, the ADC value of malignant lesions was lower than that of benign lesions. (3)The ADC value of different types of malignant tumors was significantly different. (4) DWIBS can be used in tumor screening and the therapeutic evaluation due to its large range scan.

MSCT Features of Diffuse Panbronchiolitis

XIAO Shu-kai, BAI Jun, XIANG Zi-yun

2012, 21(1): 119-124.

Abstract(1528) PDF(0)

Abstract:
Objective: To study features of diffuse panbrochiolitis(DPB) on high resolution computed tomography(HRCT).Methods: Retrospective analysis of radiographic and pathologic data of 5 patients with DPB was made.Results: 5 patients with DPB presented with centrolobular non fused node shadows being distributed diffusely on both lung fields.Typical chest HRCT scan showed “tree-in-bud” in 2 cases;the wall being thickened in small airway,tubular or ring shaped cap illary bronchiectasis in 3 cases;centrilobular emphysema in 3cases;paranasosinusitis in 5 cases.Conclusion: DPB have characteristic imaging features,which are the key to accurately diagnose this disease,particularly on HRCT.

The Value of DSCT in Quantitative Assessment of Left Ventricular Function of Coronary Heart Disease with T2DM

PENG Dong-hong, SHEN Bi-xian, TAN Si-ping, PENG Ke-wen, HUANG An-rong, CHEN Sheng-ji

2012, 21(1): 125-132.

Abstract(565) PDF(0)

Abstract:
Objective: To explore the value of DSCT in quantitative assessment of left ventricular function of coronary heart disease with T2DM.Methods: All of 152 CHD patients including 76 cases with T2DM and 76 cases without DM were performed angiographies by DSCT.Then the left ventricular function and characteristics of coronary artery were analyzed and compared between two groups.58 cases of them underwent cardiac DSCT and echocardiography examination within three days.Compared the correlations between DSCT and echocardiography in quantitative assessment of left ventricular functional parameters.Results: DSCT and echocardiography had good correlation for EF(r=0.702),ESV(r=0.874),SV(r=0.828) and EDV(r=0.898).There was no significant difference among the measurements between DSCT and echocardiography(P>0.05).The ESV and EDV measured by DSCT in the T2DM group were higher than that in non-DM group,while the EF was lower in the T2DM group.There was statistically significant between two groups(P<0.05).Calcification score had significant increase in T2DM group as compared with that in non-DM group.Three branch vessel lesion,severe stenosis and total occlusion of CHD with T2DM group have much more than that of CHD with non-DM group,while CHD with non-DM group have more one-vessel lesion and mild stenosis.Conclusion: DSCT is an accurate and feasible methods to assess the left ventricular function.The data obtained from one time coronary artery angiography can not only be used to evaluate left ventricular function but also to analysis the characteristics of coronary artery lesion.Compared with non-DM patients,the T2DM patients have more,extensive and severe coronary artery lesion and worse left ventricular function.

New Advances of Compressed Sensing in Medical Image Reconstruction

JIAO Peng-fei, LI Liang, ZHAO Ji

2012, 21(1): 133-147.

Abstract(755) PDF(6)

Abstract:
Compressed Sensing(CS) is a new signaln acquisition and processing theory.It can decrease the signal sampling time and computation cost by reducing the required data for signal recovery while maintaining good image quality.The CS theory has drawn a lot of attention and made great progress in medical imaging since it was proposed.This paper introduces the history of CS theory and the recent improvement in medical imaging. Moreover,we focus on the dictionary learning algorithm which is a new CS-based adaptive reconstruction algorithm.At last,the result of simulation is presented to convince the algorithm.

New Progress of Post 64 Slice CT for Coronary Artery

ZHAO Yi-qin, ZU De-gui, ZENG Qing-yu

2012, 21(1): 149-155.

Abstract(562) PDF(0)

Abstract:
64-slice CT coronary artery imaging has gradually become the important noninvasive test of diagnosis and screening for coronary artery disorder,whose quality is still limited by cardiac arrhythmia,tachycardia,calcification and stents,and it has excessive radiation dose.The paper sums up the progress and disadvantage of post 64 Slice CT such as dual CT,Brilliance ICT,Gemstone CT,and 320 slice CT,shows the radiation dose has been cut down,indicates that tachycardia is settled essentially in Dual CT and Brilliance ICT with the improvement of temporal resolution and cardiac arrhythmia is resolved radically in 320 slice CT,at last,discusses the investigative foreground of post 64 Slice CT for coronary artery.

Review of the Application of Computed Tomography Technology in Safety Inspection Domain

ZHENG Jin-zhou, LU Shao-dong

2012, 21(1): 157-165.

Abstract(724) PDF(7)

Abstract:
Among the various technologies of safety inspection,CT technique has become one of effective technologies.The first generation X-ray CT has high radio of wrong alarm and missing alarm.The new development has solved this problem.Comparing with X-ray security inspector,CT's security inspector have many advantages,because it is fundamental improvement.The fundamental improvement is three-dimensional imaging and determining density and the atomic number,overcoming the problem-double image of the X-ray security inspector.This techology can accomplish comparing physical characteristics with dangerous materials automaticly,reducing influence from human beings.The result is to lighten labor intensity of secruity staffs,also to guarantee the effect of security check.With the terrorism creeping all round the world,there is a large market for CT's security inspector.

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2012 Vol. 21, No. 1