CT理论与应用研究

Study of OSEM with Different Subsets in Fan Beam Reconstruction

YIN Yin, LIU Li

2003, 12(3): 1-8.

Abstract(809) PDF(4)

Abstract:
Purpose: A fast iterative image reconstruction method―OSEM (Ordered Subsets Expectation Maximization) is applied in the reconstruction of fan-beam projections of a Phantom, and the effective range of OSEM parameters (such as iterative number, subset order) is verified, and the OSEM with various subset orders are studied by comparing their reconstructive image quality and convergent speed. Method: The probability matrix of fan-beam geometry is calculated in advance and maximum interval between subset is assumed. Result: In the reconstruction of a simulated Phantom data, OSEM gives better images with higher spacial resolution and lower noise, as compared with traditional FBP method especially under noisy acquisition situation in fan-beam scanning, and in a certain extension the image quality is proportional to the product of the iterative number and the subset order, while computing time is only related to the iterative number. Conclusion: Good images with smaller iterative number and thus shorter time can be obtained by properly choosing the subset order in fan-beam OSEM reconstruction.

The Study of Relationship between Circular Orbit Cone Beam Reconstruction Error and Cone Angle

CENG Kai, CHEN Zhi-qiang, ZHANG Li, ZHAO Zi-ran

2003, 12(3): 9-16.

Abstract(703) PDF(2)

Abstract:
Objective The Study of Relationship between Circular Orbit Cone Beam Reconstruction Error and Cone Angle. Method : Compared with 2-D CT reconstruction, Cone-Beam reconstruction has several advantages, and now it has been implemented more and more widely. Circular orbit based Cone-Beam reconstruction algorithms, which are mathematically simpler and more feasible than other algorithms, are more favorable. However, because of the limitation by circular orbit, we cant obtain all the data in Radon Space which means that the result becomes better with the cone angle decreases. So it is important to study the relationship between the cone angle and the reconstruct quality further. Results : In this paper we obtain a relationship between the error and the cone angle with some approximation. Conclusion : Then we propose some ways to improve circular orbit based Cone-Beam algorithms.

Key Problems in the Research of Magnetic Induction Tomography

WANG Cong, DONG Xiu-zhen, QIN Ming-xin

2003, 12(3): 17-21.

Abstract(756) PDF(0)

Abstract:
Objective The basic principle and the significance of MIT are introduced. Method Four key problems in the research of MIT are discussed. Result Analysis and comparison on these problems are made between several foreign rearch groups. Conclusion The prospect of the development of MIT is made.

Multi-spiral CT Diagnosis for Aortic Dissection

ZHANG Jia-li, WANG Hao, DENG Bi-yi, CUI Bing

2003, 12(3): 22-25.

Abstract(766) PDF(0)

Abstract:
Purpose To evaluvate the multi-slice spiral CT (MSCT) technique in diagnosing the aortic dissection (AD). Methods 15 cases with AD were performed by whole aorta MSCT angiography,all data were processed with 2D and 3D reconstructions,the main methods included: MPR,CPR,SSD and MIP. Results All cases were diagnosed as arotic dissection and classified correctly. In 15 cases, true and false cavity, intimal flap, mural thrombus and calcification of AD were displayed. In 12 of all cases, the location of intimal rupture were displayed. The SSD and MIP images of AD displayed the relationship between AD and neighboring organs clearly and directly. Conclusion MSCT is an effective and non-invasive method in diagnosis, classification and location of intimal rupture of AD.

Value of High Resolution CT and Spiral CT Enhanced Scanning in Diagnosis of Small Peripheral Lung Cancer

XU Chun-lin, LIU Wei, WANG Jian-guo, PENG Lei, ZHANG Xue-mei, KANG Su-ping

2003, 12(3): 26-30.

Abstract(836) PDF(0)

Abstract:
Objective To evaluate the value of high resolution CT and spiral CT enhanced scanning in diagnosis of small peripheral hung cancer. Methods The authors collected 46 patients with pathologically-proved small peripheral lung cancer (≤3cm in diameter). All cases were scan by high resolution CT. To study the stigmata of all. Spiral CT enhanced scanning was done in 25 patients, Analysis stigmata of the increasing range in CT value in reinforcement anterior and posterio. Results Manifest of high resolution CT scanning:①lobulation sign (91.3%);②spiculatecd sign(87%);③pleural indentation sign (78.3%);④vascularnotch sign (54.3%);⑤sign of air bronchus and vacuole (34.8%);⑥spinose processus (32.65%);⑦milling glass dens (10.9%);⑧calcification (8.7%). The increasing range in CT value in reinforcement anterior and posterio 20~30 HU (16%), 30~65 HU(76%),>65 HU(8%). Conclusion High resolution CT and spiral CT enhanced scanning were important method in the diagnosis of small peripheral lung cancer. The final diagnosis which are of more than 3 sign on CT or above all are 2 sign in anterior 5 sign, precision rate(91.3%). The icereasing range in CT value in reinforcement anterior and posterio 20~30 HU, It is terrier reliable in diagnosis of lung cancer, precision rate (92%).

X-ray and CT study of esophageal cancer

HUANG Shao-quan, TAN Jiang-cheng, CHEN Shu-ke, LONG Hai-dan

2003, 12(3): 31-33.

Abstract(873) PDF(0)

Abstract:
Objective : To study the X-ray and CT diagnostic of esophageal cancer. Material and Method : 45 patients of esophageal cancer proved by pathology, before X-ray and CT examination. Results : 45 patients, 11 cases are in the upper segment, 18 cases in the middle segment, and 12 cases in the lower segment. The longest esophageal cancer in 45 patients is 11, esophageal wall abnormitily incrassated with ratrace and part, esophageal antrum changed stricture or obturation in different. Conclusion : There are much diagnostic acoupsur to esophageal cancer by X-ray. Both of X-ray and CT can help study the area and degree of esophageal cancer, and help clinic doctor to map out precept of treatment.

A Comparative Study of X-ray and CT in Hydrothorax

HAN Xiao-mian, TIAN Ben-xiang, YUAN Ling-jin

2003, 12(3): 34-35.

Abstract(767) PDF(0)

Abstract:
Objective To comparatively analyze the X-ray signs with the CT findings of 280 cases in hydrothorax so as to evaluate the value of CT in the diagnosis of hydrothorax. Methods 280 cases of hydrothorax were examined with fluoroscopy, X-ray anterioposterior and lateral film and CT scanning. Results The signs of X-ray were compared with the specific symptoms of CT. Conclusion We can diagnose precisely if the hydrothorax is caused by the inflammatory lesion or benign and malignant tumor.

2003, 12(3): 34-37.

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Abstract:

Reaserch on Section Adjustment Using Polymer in Jilin Xinli Fracturing Oil Filed by NMRI

SHANG Gen-hua, LIU Li, YANG Di, GUO Dong-ming, QIAN Li-feng

2003, 12(3): 40-45.

Abstract(688) PDF(1)

Abstract:
Objective : Study the polymer section adjustment using in Jilin Xinli fracturing oil filed. Methods : NMRI and mutilayers models were used in the paper. Result : NMRI and mutilayers model is suitable for the research on polymer section adjustment. Conclusions : The developing degree of low and middle permeability layers were improved after the adjustment in high permeability area.

Imaging Synthetic Scheme for Underground Medium and Material-transport

GUO Lü-can

2003, 12(3): 53-55.

Abstract(651) PDF(1)

Abstract:
Objective : Making reference to the development of weather forecast and increasing meteorological parameter in weather predication process, the author provide an Imaging Synthetic Scheme for underground material-transport, by introducing the comparison methodology. This synthetic scheme may including to explore the seismic active faults, to reveal some basic characteristics of the spatial distribution of groundwater and magma chamber, and to inspect the seismic activity in reservoir region and hoping to predict the earthquake risk in some seismic belts. Materials and Methods : Detecting the seismic belts by means of "seimic tomography method" getting seismic profile. The resistivity tomography has been widely used in exploring potential faults and ground water and magma chamber. The resistivity image distribution may be combined with nuclear magnetic resonance tomography(NMR). Conclusion and result : In this paper comparison and research by the methodology principles, technology and application between weather process and underground material-transport are made, and suggestion for detection of groundwater with NMR technology are combined with seismic tomograpy and resistivity tomography method and other well-known seismic detect methods, for exploring underground medium and material-transport and its dynamic process, serving in estimate the seismic risk and the possibility of volcano eruption.

Research and Discussion for CT Image Quality Evaluation

WANG Xue-li

2003, 12(3): 46-52.

Abstract(847) PDF(1)

Abstract:
Objective : this paper only discusses the typical methods for CT image quality evaluation considering that different vendors use different evaluation methods. Methods : we discuss the typical CT image quality evaluation techniques. Results : principles and issues to be paid more attention. Conclusion : this paper will give CT researchers and doctors?good guide or hint for comprehending the information in the clinical images.

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2003 Vol. 12, No. 3