ISSN 1004-4140
CN 11-3017/P

2011 Vol. 20, No. 1

CT Theory
Tomosynthesis Projection Simulation Based on GPU
YAN Tian-feng, SUN Yan, SUN Yi
2011, 20(1): 1-10.
Abstract(1784) PDF(5)
Tomosynthesis can reconstruct any sectional image of object using limited angle projection. Before the research of reconstruction method,projection simulation is an important step,this paper proposed a projection simulation method based on GPU Raycasting algorithm. Comparing to CPU simulation method,GPU simulation method is faster in calculation and much closer to the practical projection based on hardware-based trilinear interpolation. This paper simulates projection using traditional CPU method and GPU method respectively,reconstructs the projections above by ART algorithm and Wavelet-Galerkin algorithm and achieves good results.
A Kind of NURBS Surface Reconstruction Method for Industrial CT Cloud Data
CHEN Si, CHEN Hao, LI Shou-tao
2011, 20(1): 11-20.
Abstract(1520) PDF(1)
Though CT technique has been developed for more than forty years,there are many difficulties in ensuring precision of surface reconstruction. For the Scattered Points from industrial CT image,a data pre-processing is implemented. After the process of extracting datapoint,the algorithms of fitting,interpolation and approximation is presented. Taking example for the scatter points which translate from CT image of a part by VG,the data pre-processing and approaching algorithm are implemented with VC++ and OpenGL software. The approach is proved to be correct by the example.
Base on Date Extraplation Improve ART Iterations Algorithm
LI Yi, PAN Jin-xiao
2011, 20(1): 21-27.
Abstract(1633) PDF(5)
In order to reconstruct high-quality image from projection data at limited angle,we develop an improved fast iterative reconstruction algorithm. The basic idea of this algorithm is that used the perspective of data to complete unknown perspective projection data is applied,and the image can be made by Algebraic Reconstruction Technique(ART). In the end,we have performed numerical experiments using computer simulation data. Experimental results demonstrate that the proposed algorithm not only improves the quality of image reconstructed,but also significantly increases the convergence speed of iteration image.
Depth Migration Based on Arbitrarily Wide-Angle Wave Equation with Parameters Optimization
SUN Qi-feng, BAI Qing-yun
2011, 20(1): 29-38.
Abstract(1476) PDF(1)
It is difficult to image the geological structure with strong lateral variation and steep dip. On the basis of the Arbitrarily Wide-Angle Wave Equation(AWWE),we implemented migration with finite difference high-split scheme in frequency-space domain. Optimization of the velocity parameters is a key factor in the accuracy of imaging. The test of impulse response clears that the low order AWWE can be adapted to higher steep dips by optimization of the parameters. The pre-stack migration of Marmousi data shows that the method can handle strong lateral variation and steep dip.
Application of 3D High Density Resistivity Tomography in Engineering Detection of Complex Condition
XU Shun-qiang, LIU Wen-chao, LI Qing-lin, CHEN Zhi-guo, WANG Shi, QIN Jian-zeng, HE Yong-bo
2011, 20(1): 39-46.
Abstract(1374) PDF(2)
In order to be more abundant geological target of electrical characteristics as well as more intuitive geological structure,in the case of conditions to carry out three-dimensional high-density electrical resistivity tomography to work with the two-dimensional observation method of different,three-dimensional approach to the work area venues require a higher,environmental conditions and other factors on the three-dimensional system,a greater impact. In this paper,obtained under the condition of some of the complex three-dimensional results of an analysis that in practice,in accordance with these complex conditions,targeted to take the necessary measures and methods,you can get more good results to solve the engineering geology and other issues.
CUDA-based Parallel Visualization of 3D Data
XU Sai-hua, ZHANG Er-hua
2011, 20(1): 47-54.
Abstract(1658) PDF(5)
Visualization in scientific computing is a new field of study proposed and developed in developed countries in the 20th century and the late 80's. Using Computer Graphics and Image processing techniques,3D data can be converted to graphics or images displayed on screen for interactive processing. The main methods include surface visualization and volume rendering. Ray-casting algorithm is the most classical method of volume rendering methods about 3D data,which has higher image quality but longer calculation time. CUDA-based programming technique using the GPU hypercore parallel computing function,can significantly improve the calculation speed,and realize the real-time visualization of large-scale 3D data.
Industrical CT
The Research of Reconstruction Speed for the Feldkamp-type-VOI Algorithm
SHI Ying-qin, PAN Jin-xiao
2011, 20(1): 55-61.
Abstract(1522) PDF(4)
The paper specifically describes a Feldkamp-type algorithm for the reconstruction of a volume of interest(VOI) from cone-beam(CB) projections. First,we analyze the traits of the reconstruction algorithm,and at the same time,proposes the optimization method by use of symmetry properties in the mode of cone beam scan. Finally,our proposed algorithm is tested using the three-dimensional Shepp–Logan phantom. The experimental results show that the optimization method can efficiently accelerate the speed of image reconstruction and doesn’t affect image quality.
The Research of the Performance of the Detector Materials in the CT System Based on MCNP
DAI Zhi-li, CHEN Hao, LI Ming
2011, 20(1): 63-71.
Abstract(1498) PDF(6)
The detector is one of the important devicese of the imaging system,the relationship between the detector's performance and the imaging system's indices is tightness. So the calculation of the detector materials's performance is an importan work in imaging system design. This paper simulats the performances(detection efficiency,energy deposition,effective deposition factor) of three kinds of detector materials,which is a basic work to design the high quality imaging system.
Medical CT
An Interactive Approach for Skull Defect Repair Based on CT Sequence Datasets
LÜ Xin-rong
2011, 20(1): 73-82.
Abstract(1578) PDF(2)
Skull bone is one of the most important parts in the human's body,which protects and supports the brain tissues. Nowadays,due to many various reasons,a lot of people suffer from the skull bone defects,which not only affect the appearance,but also may cause brain damages. How to repair the skull bones for people effectively has become an international hot topic. At present,doctors diagnose the state of the bone defect illness mainly depending on observing the CT images of patients,and make the repair model by hand. It mainly depends on the technique and experience of the doctors. In order to solve this problem,this paper focuses on using the interactive technology to make the skull repair procedure efficient. During this process,we used B-Spline to repair some typical slices or each slice of the CT images,construct the restoration that fits the skull surface and then transfer it as a file in specific format to a machine based on technology of computer aided design and computer aided manufacture to produce a real restoration. This method can shorten the time of operation,reduce the risk of operation,and produce a suitable repair result for patients.
X-ray and CT Image Analysis of Pelvic Fractures
ZHU Hua-qiang, LIU Si-run, QIU Jian, LUO Dong-mei, ZHOU De-ming
2011, 20(1): 83-90.
Abstract(1822) PDF(3)
Objective: To summarize X-ray and CT imaging characteristic for pelvic fracture and analyze the missed diagnosis reason. Methods: Retrospectively analyzed 620 cases of pelvic fracture with X-ray and spiral CT image data,to compare detection rate and analyze the missed diagnosis reason. Results: There were 1036 fractures in quantity and 38 dearticulation of 620 cases. 255 iliac fractures,226 acetabular fractures,99 sacral and coccyx fractures,341 pubic upper and lower branches fractures,115 ischia fratures,20 cases of dislocation of hip joint and sacroiliac joint. About 169 micro-fractures,1 post dislocation of hip joint,5 mild dislocations of sacroiliac joint and 3 mild separation of pubic symphysis were mis-diagnosed by X-ray. Fracture detection rates of X-ray plain is 83.7% and dislocation detection rates is 76.3%;Among 226 acetabular fractures,X-ray plain and SSD mis-diagnosed about 61 and 20 fractures separately. The detection rate of X-ray plain and SSD of fracture was 73.0 % and 91.2%. In 99 sacral and coccyx fractures,X-ray plain and SSD mis-diagnosed about 48 and 11 cases,the fracture-dislocation detection rate was 56.0% and 89.9% separately. Through χ2 examination,X-ray plain and CT of pelvic fracture had differences in statistically(p<0.05). There's no statistical difference between SCT/MPR and SSD(p>0.05). Conclusion: The performance of spiral CT is better than X-ray examination in the detection of pelvic fracture. Spiral CT with MPR and SSD could clearly reveal the detail of fracture,improved the preoperative diagnosis and facilitated surgical treatment.
Clinical Significance of the Basilar Cistern and Brain Midline Dynamic Observation of the Acute Head Injury in CT
HU Shao-ping, ZHOU Li-qiang, SONG Huai
2011, 20(1): 91-97.
Abstract(1681) PDF(2)
Objective: To study the clinical significance of acute brain injury and brain midline basilar cistern dynamic observation of CT. Materials and methods: Right from May 2007 to July 2009 among 150 patients admitted with full information for basilar cistern and brain midline of the change in CT with acute head injury and to study the relationship between the prognosis of patients. Results: Narrowed by the basal cistern and extent of midline shift was divided into Ⅳ,this set of data shows the death rate in patients with traumatic brain injury type of the increased CT significantly improved,dynamic observations of the development of the disease with mortality rates significantly increased. Conclusion: Dynamic pool of acute brain injury and brain midline basal CT image changes,to predict prognosis and guide the rescue have important clinical significance.
Duodenal Stromal Tumors:Correlation of Imaging Appearances vs Patholigical Findings
ZHAN Yong, XIANG Zi-yun, TAN Qi, CAI Han-shou, WANG Jing-bo, WU Ming-can
2011, 20(1): 99-106.
Abstract(1610) PDF(3)
Purpose : To analyze the characteristics of CT and MR of duodenal stromal tumors. Materials and Methods: The CT and MR findings of 16 patients with primary duodenal stromal tumors were analyzed retrospectively,and compared with their pathological results. CT scanning were performed in 12 cases and MR in 4 cases. Results: Pathological report:borderline tumor 5 cases,low-grade malignant tumor 4 cases,moderate /high-grade 7 cases. On CT/MRI,the lesions presented as round and lobulated solid Masses and cystic-solid mixed masses. On non-enhanced CT/MRI,the lesions appeared as mixed density/signal intensity masses. After contrast administration,the solid masses and the solid portions of the tumors demonstrated significantly enhancement in arterial phases and still keep enhancement the portal phases. The non-enhancement portions represented necrosis. Calcification was found in 3 cases and air-filled cavity in 5cases. Conclusion: The findings of CT and MRI of duodenal stromal tumors were related with their pathological characteristics. CT and MRI can supply valuable information for the locations of duodenal stromal tumors,and MRI was more effective in displaying hemorrhage,cystic degeneration of the lesions than CT.
The Imaging Features of 64-MDCT Angiography in Diagnosis of the Intimal Flap Entry of Aortic Dissection
WANG Xu, CENG Qing-yu, ZU De-gui
2011, 20(1): 107-114.
Abstract(1460) PDF(0)
Objective: To analysis the correlation with the position of the intimal flap entry and the involved aortic branch of aortic dissection(AD). Methods: Seventy-one patients with AD underwent 64-MDCTA examination,and the source images transferred to computer workstation subsequently post-processed using MPR,VR,CPR,MIP. Results: The entry of intimal flap could be shown in all of 71 patients. There were 270 entries of the intimal flap. And there are 208 branch which were involved,at the level of the involved branch,27.84% have entries in the main branch of the aorta,94.81% have entries in the ramiparietals. Conclusion: The position of the entry and the involved aortic branch have high correlation.
CT Analysis of Degenerative Lesion in Lumbar Zygapophysis
HUANG Shao-quan, YE Jun, CHEN Xue-lian, ZOU Shi-lin, KUANG Yong-cai, LIU Yong-bin
2011, 20(1): 115-122.
Abstract(1429) PDF(0)
Objective: To improve cognition of degenerative lesion in lumbar zygapophysis. Materials and methods: To analysis the CT images of the 60 cases with bone window and soft tissue window. Results: in 60 cases,CT findings of degenerative lesion in lumbar zygapophysis were founded proliferation hardening in 14 cases,hypertrophy in 6 cases,bone rarefaction in 21 cases,osteophyma in 18 cases,subluxaion in 9 cases;it was founded cataplasis in joint space with narrowing in 20 cases,unevenness in 17 cases,underpressure in 19 cases,corpus liberum in articular cavity in 6 cases;it was founded changes in articular facet with uneven in 53 cases,hardening in 34 cases,calcification in articular capsule in 5 cases,calcification with arcuate ligaments in 5 cases,and thickening in 4 cases. Conclusion: Thin slice CT scanning can accurately diagnose the degenerative lesion in lumbar zygapophysis and provid reliable images for treatmeat.
Discussion on Maintenance and Service of Spiral CT
2011, 20(1): 123-129.
Abstract(1491) PDF(1)
In this article,the maintenance and service of spiral CT are discussed on three aspects according to priority based on the use and environment trait of it:fistly the significance of preventive maintenance is emphasized and correlative methods are introduced;the requests and preparations of immediate service are described later;some experiences and principles are summarized by example analyses of services lastly.
Review of Metal Artifacts Correction Methods on X-ray Computed Tomography
LI Qing-liang, YAN Bin, SUN Hong-sheng, LI Lei, ZHANG Feng
2011, 20(1): 131-140.
Abstract(1339) PDF(4)
In the system of CT imaging,for the objects with high density metal,CT images reconstructed by the standard filtered-back-projection(FBP) algorithm generate significant streak artifacts. These artifacts seriously influence image quality and bring huge difficulties for judgment. Correction method of metal artifacts has become the hot and difficult issue of CT technique. The paper formulates the cause of metal artifacts,and sums up the correction methods of metal artifacts developed this year,at last,discusses the investigative foreground of correction methods of metal artifacts.
Multi-energy X-ray Imaging Technique and Its Application in Computed Tomography
HAO Jia, ZHANG Li, CHEN Zhi-qiang, XING Yu-xiang, KANG Ke-jun
2011, 20(1): 141-150.
Abstract(1301) PDF(5)
With the rapid development of X-ray detectors,photon counting energy dispersive detectors become more and more popular in X-ray imaging area. Using this kind of detectors,a polychromatic X-ray spctrum can be seperated into different energy regions and the photon number in each energy region can be counted independently,thus attenuation coefficients under different photon energies can be obtained. Multi-energy X-ray imaging technique opens up new perspectives within the fields of X-ray imaging. This paper introduces the latest development of photon counting X-ray detector and its application in medical imaging. Also some advantages of this technique in CT imaging are presented in this paper such as dose reduction,SNR improvement and precision improvement of material discrimination. Recently,a lot of research institutes are dedicated to faster electronic device and readout chip for photon counting detectors. With the rapid development of multi-energy imaging,it will bring a large revolution for X-ray imaging.