Top View
1
2000, 9(2): 19-21.
Abstract：
To evaluate the application of the am in the clinical medicine. Materialsand Methods:With the help of GE Signa Horizon un systen and the method of BOLD, 16 patientswere examined who suffered from the cerebral thrombosis. T1 xveighted images were obtained tvith spinecho pulse sequence, and T2* weighted images witll sillgle shot gradient echo planar unagliW pulsesequence. With the Sun Sparc workstation and related software, and stahshcal methods such as student t-test and correlation the data were analyzed. Results: The majority of the patients in the control group hada stable state in a short time after admission to hospital, and the disease reerudesced soon after stoppingthe remedy of dehydration and encephalic pressure reduction given exeept 2 younger pahents. The fMRIresults showed that there wer active areas within the brain only in 2 cases of this group. In theexperimental group, all patients had a stable state in the period of treatment and the functions of theirtroubled limbs were remarkably reeovered. With fMRI, it was also found that there were achve areas inthe primary motor cortex. Conclusion: It is an objective and effective intuentality for fMRI to inspectthe functional resumption of the pahents Who suffered from Cereral thrombosis. Besides, it is also hintedthat the curative effeet was very good When using the remedy of coreral dricro-circulation such as theginkgo biloba extract in the acute period of the disease, and was different with and without it.
To evaluate the application of the am in the clinical medicine. Materialsand Methods:With the help of GE Signa Horizon un systen and the method of BOLD, 16 patientswere examined who suffered from the cerebral thrombosis. T1 xveighted images were obtained tvith spinecho pulse sequence, and T2* weighted images witll sillgle shot gradient echo planar unagliW pulsesequence. With the Sun Sparc workstation and related software, and stahshcal methods such as student t-test and correlation the data were analyzed. Results: The majority of the patients in the control group hada stable state in a short time after admission to hospital, and the disease reerudesced soon after stoppingthe remedy of dehydration and encephalic pressure reduction given exeept 2 younger pahents. The fMRIresults showed that there wer active areas within the brain only in 2 cases of this group. In theexperimental group, all patients had a stable state in the period of treatment and the functions of theirtroubled limbs were remarkably reeovered. With fMRI, it was also found that there were achve areas inthe primary motor cortex. Conclusion: It is an objective and effective intuentality for fMRI to inspectthe functional resumption of the pahents Who suffered from Cereral thrombosis. Besides, it is also hintedthat the curative effeet was very good When using the remedy of coreral dricro-circulation such as theginkgo biloba extract in the acute period of the disease, and was different with and without it.
2
Abstract：
With multislice CT appearing, the scanning speed was improved enormously. The images of multislice can be acquired simultaneously by once-through scanning, and sufficient informations were postprocessed. It was important that the scanning parameters were choosed rightly. The article expounds the pitch, thickness, reconstructing space of multislice CT, which influences the imaging quality.
With multislice CT appearing, the scanning speed was improved enormously. The images of multislice can be acquired simultaneously by once-through scanning, and sufficient informations were postprocessed. It was important that the scanning parameters were choosed rightly. The article expounds the pitch, thickness, reconstructing space of multislice CT, which influences the imaging quality.
3
2008, 17(2): 1-7.
Abstract：
Exact three-dimensional reconstruction algorithms are usually based on the three-dimensional Radon transform which is also widely used in other related fields. However, Radon transform consists of all Radon values placed at the corresponding points. Each value is defined as a plane integral in the object domain. So, the computation of Radon value is rather time expensive using direct integral method. New applications based on it may become convenient if a fast and efficient transformation algorithm is adopted. Therefore, an analytical method is proposed to compute the 3D Radon transform in this paper that is based on 3D S-L phantom including spheres and further compare it with the traditional algorithms of their advantages and disadvantages. Finally, the origin object reconstructed by 3D inverse Radon transform has been proved right by the result from computer simulation.
Exact three-dimensional reconstruction algorithms are usually based on the three-dimensional Radon transform which is also widely used in other related fields. However, Radon transform consists of all Radon values placed at the corresponding points. Each value is defined as a plane integral in the object domain. So, the computation of Radon value is rather time expensive using direct integral method. New applications based on it may become convenient if a fast and efficient transformation algorithm is adopted. Therefore, an analytical method is proposed to compute the 3D Radon transform in this paper that is based on 3D S-L phantom including spheres and further compare it with the traditional algorithms of their advantages and disadvantages. Finally, the origin object reconstructed by 3D inverse Radon transform has been proved right by the result from computer simulation.
4
2022, 31(1): 117-134.
DOI: 10.15953/j.1004-4140.2022.31.01.14
Abstract：
Computed tomography (CT) is widely used in clinical diagnosis because of its fast imaging speed and high resolution. However, higher doses of radiation will cause damages to human tissues and organs, while lower doses will lead to serious deterioration of imaging quality. In order to solve the above contradiction, researchers have focused on the low-dose CT imaging technology to study how to reduce the harm caused by radiation to the human body to the greatest extent under the condition of ensuring the imaging quality to meet the needs of clinical diagnosis. In recent years, deep learning has developed rapidly in the field of artificial intelligence, and has been widely used in image processing, pattern recognition, signal processing fields. Driven by big data, LDCT imaging algorithms based on deep learning have made great progress. This paper studies the development of low-dose CT imaging algorithms in recent years in terms of three aspects: the process of CT imaging, the noise modeling of low-dose CT, and the design of imaging algorithms. In particular, the imaging algorithms in the field of deep learning are systematically elaborated and analyzed. Finally, future developments in the field of LDCT image artifact suppression are also prospected.
5
2008, 17(2): 15-27.
Abstract：
The regional travel-time data from 475 seismic stations in the North China and its vicinity were used to inverse the P and S velocity structures of the crust and uppermost mantle.The pseudobending ray tracing algorithm was used to calculate the travel times.The large and sparse system of observation equations is solved by using the LSQR algorithm.According to the checker-board tests,reliable inversion results were obtained for a parameterized model with grid size of 0.5°by 0.5°in the horizontal directions and 5 nodes of 1,10,25,42 and 60 km in depth.The Yangtze Block and the Sino-Korean Block are located in two sides of the Qinling-Dabie orogenic belt.The differences of velocity structure between two Blocks are that lower velocity anomaly exists in most part of the Sino-Korean Block,while velocity distribution is normal in the Yangtze Block.This indicates that the Yangtze Block is relative stable,and the Sino-Korean Block is still active,where strong earthquakes have frequently occurred.Main features of the velocity structure in the Sino-Korean Block are that major tectonic belts (such as Yanshan uplift,Taihangshan piedmont fault belt,Tanlu fault belt,and Qinling-Dabie orogenic belt)are located in the low velocity areas or the transition zone from low velocity area to high velocity area in the crust and upper mantle.In the Tangshan earthquake area,low velocity anomaly commonly exists at the depth of 25 km,42 km and 60 km,which may imply that the hot material in upper mantle upweUs,and then stops to the lower part of upper crust.
The regional travel-time data from 475 seismic stations in the North China and its vicinity were used to inverse the P and S velocity structures of the crust and uppermost mantle.The pseudobending ray tracing algorithm was used to calculate the travel times.The large and sparse system of observation equations is solved by using the LSQR algorithm.According to the checker-board tests,reliable inversion results were obtained for a parameterized model with grid size of 0.5°by 0.5°in the horizontal directions and 5 nodes of 1,10,25,42 and 60 km in depth.The Yangtze Block and the Sino-Korean Block are located in two sides of the Qinling-Dabie orogenic belt.The differences of velocity structure between two Blocks are that lower velocity anomaly exists in most part of the Sino-Korean Block,while velocity distribution is normal in the Yangtze Block.This indicates that the Yangtze Block is relative stable,and the Sino-Korean Block is still active,where strong earthquakes have frequently occurred.Main features of the velocity structure in the Sino-Korean Block are that major tectonic belts (such as Yanshan uplift,Taihangshan piedmont fault belt,Tanlu fault belt,and Qinling-Dabie orogenic belt)are located in the low velocity areas or the transition zone from low velocity area to high velocity area in the crust and upper mantle.In the Tangshan earthquake area,low velocity anomaly commonly exists at the depth of 25 km,42 km and 60 km,which may imply that the hot material in upper mantle upweUs,and then stops to the lower part of upper crust.
6
2004, 13(1): 25-28.
Abstract：
<b<objective</b< To discuss imaging appearance of benign and malignant disease of solitary pulmonary nodule(SPN) and characteristic of diagnosis. <b<Material and Methods</b< 17 patients with pathologically-proved pulmonary nodule (diameter<3.0cm),including males 11cases and females 6 cases with the age of 38-83years (average 63.2 years).using helical CT scan with PQ5000,in them 7cases do contrast CT scans,5 cases do three dimension configuration. <b<Results</b< among 17 cases, malignant disease is 12 cases, benign disease is 5 cases,in malignant disease adenocar-cinoma is 8 cases and squamous-cinoma is 2 cases,in benign disease tuberculosis is 3 cases, inflammation node is 2 cases, the common CT signs included lobulation sign (14 cases),pleural tail sign(7 cases),vessel convergence (8 cases),and spiculation (14 cases),with inhomogeneous (13 cases). <b<Conclusion</b< CT scans about pulmonary nodus have important value in differentiate benign and malignant disease.
<b<objective</b< To discuss imaging appearance of benign and malignant disease of solitary pulmonary nodule(SPN) and characteristic of diagnosis. <b<Material and Methods</b< 17 patients with pathologically-proved pulmonary nodule (diameter<3.0cm),including males 11cases and females 6 cases with the age of 38-83years (average 63.2 years).using helical CT scan with PQ5000,in them 7cases do contrast CT scans,5 cases do three dimension configuration. <b<Results</b< among 17 cases, malignant disease is 12 cases, benign disease is 5 cases,in malignant disease adenocar-cinoma is 8 cases and squamous-cinoma is 2 cases,in benign disease tuberculosis is 3 cases, inflammation node is 2 cases, the common CT signs included lobulation sign (14 cases),pleural tail sign(7 cases),vessel convergence (8 cases),and spiculation (14 cases),with inhomogeneous (13 cases). <b<Conclusion</b< CT scans about pulmonary nodus have important value in differentiate benign and malignant disease.
7
Abstract：
The cone-beam CT (CBCT) system based on the two-dimensional flat-panel detector technology is widely applied in patient location verification before radiotherapy. However, during the application of intraperitoneal tumor radiotherapy, severe shading and streaking artifacts caused by respiratory movement and intestinal peristalsis make it difficult to distinguish tumor areas from the CBCT images. Due to the non-rigid deformation of flexible organs such as the pancreas under the action of respiratory motion, it is hard to quantify deviation between the body surface motion monitoring results and the actual organ motion, and it is also difficult to monitor irregular motion represented by intestinal peristalsis. There is no effective solution to motion artifact correction in CBCT. Based on theory of biodynamics and common knowledge of human physiology, in this paper we propose a brand new radiotherapy image-guided cone-beam CT motion artifact correction method without motion monitoring or implantation of in-vivo markers. The proposed artifact correction strategy is designed based on the features of the artifact images and fusion of various CT image domain processing algorithms. The results suggest that the image quality of cone beam CT has been significantly improved after the application of this strategy in the clinical abdominal CBCT image processing. The average CT number error in typical soft tissue areas reduces from 90 HU to 30 HU, and the boundary of the intestinal cavity and surrounding soft tissue information are partially recovered. The proposed artifact correction strategy does not require respiratory gating or increase of projections, which can be integrated into existing workflows without marker implantation surgery. The motion-artifact-corrected CBCT images provide more accurate tumor localization information for image-guided radiotherapy of pancreatic carcinoma. The proposed method is proved practical and efficient for clinical applications
8
2006, 15(1): 11-14.
Abstract：
Objective : To investigate MR manifestation of lumbar myeloid inverse conversion and differential diagnosis of common pathogeny. Methods : To collect the clinical,laboratory and image data of 14 patients which MR manifest lumbar myeloid inverse conversion in our hospital,among them 6cases of metastatic tumor,2cases of multipl myeloma,1 cases of myelofibrosis,5cases of tumor after chemotherapy. Results : 5 cases' lumbar MR manifest uniformity hypo-signal in T1WI,uniformity hypo-signal in T2WI.9 cases' lumbar MR manifest multiple patchy and mottling hypo-signal under equi-signal background in T1WI,and isparate numerus hypo-signal under equi-signal background in T2WI,among them 3cases involved in lumbar accompaniment,2cases emerged tumeur in the side of the lumbar and in epidural space respective. Conclusion : Lumbar myeloid inverse conversion generated in the patients of metastatic tumor,multiple myeloma,myelofibrosis and tumor after chemo-therapy,which MR manifestation is less of specific characteristic,definitely diagnoses required to combined with the data of clinic,laboratory and examination.
Objective : To investigate MR manifestation of lumbar myeloid inverse conversion and differential diagnosis of common pathogeny. Methods : To collect the clinical,laboratory and image data of 14 patients which MR manifest lumbar myeloid inverse conversion in our hospital,among them 6cases of metastatic tumor,2cases of multipl myeloma,1 cases of myelofibrosis,5cases of tumor after chemotherapy. Results : 5 cases' lumbar MR manifest uniformity hypo-signal in T1WI,uniformity hypo-signal in T2WI.9 cases' lumbar MR manifest multiple patchy and mottling hypo-signal under equi-signal background in T1WI,and isparate numerus hypo-signal under equi-signal background in T2WI,among them 3cases involved in lumbar accompaniment,2cases emerged tumeur in the side of the lumbar and in epidural space respective. Conclusion : Lumbar myeloid inverse conversion generated in the patients of metastatic tumor,multiple myeloma,myelofibrosis and tumor after chemo-therapy,which MR manifestation is less of specific characteristic,definitely diagnoses required to combined with the data of clinic,laboratory and examination.
9
2009, 18(1): 16-22.
Abstract：
Aiming to the scatter artifacts for the flat-panel detector-based cone beam CT,a scatter correction method which need adding a Beam Attenuation Grid between the X-Ray source and the tested object was proposed.This study firstly described the device of the Beam Attenuation Grid,then educed the scatter correction algorithm based on the Beam Attenuation Grid.In order to improve the feasibility of this method,the cylinder phantom was experimented.The result showed that the method can effectively reduce the scatter artifacts and increase the quality of the reconstructed slice image.
Aiming to the scatter artifacts for the flat-panel detector-based cone beam CT,a scatter correction method which need adding a Beam Attenuation Grid between the X-Ray source and the tested object was proposed.This study firstly described the device of the Beam Attenuation Grid,then educed the scatter correction algorithm based on the Beam Attenuation Grid.In order to improve the feasibility of this method,the cylinder phantom was experimented.The result showed that the method can effectively reduce the scatter artifacts and increase the quality of the reconstructed slice image.
10
Abstract：
This paper summarizes the developing history of seismic tomography technology over past several decades in four aspects-model parameterization, forward, inversion, resolution and error analyses.Meanwhile, the comparisons of advantages and disadvantages between different methods are given.
This paper summarizes the developing history of seismic tomography technology over past several decades in four aspects-model parameterization, forward, inversion, resolution and error analyses.Meanwhile, the comparisons of advantages and disadvantages between different methods are given.
11
2001, 10(1): 5-7.
Abstract：
Purpose: It has been reported that typing was chaotic after Intra-arterial Infusion of Iodized Oil, grouping is need scary to unification. Materials and Methods: On the basis of shape of sediment the patients after TACE were separated four group. A: Rare group. B: Full mass group. C: Gappy mass group. D: Clustered group. Previous studies have shown it is futile that sediment under 30% of area, do without typing again. Results: Full mass group produce a good curative effect. Gappy mass and clustered group take effect. Rare group is futile. Conclusion: It is concluded that sediment grouping in the shape was useful for evaluate the effect of TACE for HCC.
Purpose: It has been reported that typing was chaotic after Intra-arterial Infusion of Iodized Oil, grouping is need scary to unification. Materials and Methods: On the basis of shape of sediment the patients after TACE were separated four group. A: Rare group. B: Full mass group. C: Gappy mass group. D: Clustered group. Previous studies have shown it is futile that sediment under 30% of area, do without typing again. Results: Full mass group produce a good curative effect. Gappy mass and clustered group take effect. Rare group is futile. Conclusion: It is concluded that sediment grouping in the shape was useful for evaluate the effect of TACE for HCC.
12
2008, 17(1): 56-60.
Abstract：
Objective: To research the appearances of multi-slice CT(multi-slice CT MSCT)in pulmonary hamartoma so as to improve the CT diagnostic accuracy. Methods: The CT and pathological findings of 32 cases of pulmonary hamartoma were analyzed. Dynamic contrast enhancement MSCT scanning were performed in 22 cases. All cases were confirmed by surgical operation and pathology. Results: All hamartomas had smooth edge on MSCT. Focal fat without calcification inside were present in 12 of 32 cases(37.5%), focal fat and calcification inside in 8 of 25cases (25%), calcification without fat inside in 2 of 32 cases (6.25%). The CT contrasted value was less than 20 Hu in 20 of 22 cases (90.9%). Contrast-enhancing septa were present in 16 of 22 cases(72.7%). Conclusion: Some specific MSCT features, including smooth edge, calcification and fat inside, are useful for diagnosis of pulmonary hamartoma. Dynamic contrast enhancement MSCT scanning is useful for differentiating pulmonary hamartoma with peripheral lung carcinoma.
Objective: To research the appearances of multi-slice CT(multi-slice CT MSCT)in pulmonary hamartoma so as to improve the CT diagnostic accuracy. Methods: The CT and pathological findings of 32 cases of pulmonary hamartoma were analyzed. Dynamic contrast enhancement MSCT scanning were performed in 22 cases. All cases were confirmed by surgical operation and pathology. Results: All hamartomas had smooth edge on MSCT. Focal fat without calcification inside were present in 12 of 32 cases(37.5%), focal fat and calcification inside in 8 of 25cases (25%), calcification without fat inside in 2 of 32 cases (6.25%). The CT contrasted value was less than 20 Hu in 20 of 22 cases (90.9%). Contrast-enhancing septa were present in 16 of 22 cases(72.7%). Conclusion: Some specific MSCT features, including smooth edge, calcification and fat inside, are useful for diagnosis of pulmonary hamartoma. Dynamic contrast enhancement MSCT scanning is useful for differentiating pulmonary hamartoma with peripheral lung carcinoma.
13
2023, 32(1): 139-146.
DOI: 10.15953/j.ctta.2021.067
Abstract：
Spectral CT can produce basis materials with different X-ray energies. Subsequently, the generated basis materials can be used for qualitative and quantitative evaluation of tissue components and contrast agent distribution. This approach presents a superior ability to separate and identify imaging materials compared to traditional single-energy CT. Dual-energy spectrum technology is one of the most commonly used modes in spectrum CT, which plays an important role in clinical application. In this study, the decomposition methods of a basis material in the image domain of dual-energy spectrum CT were classified into two categories: two-material decomposition and multi-material decomposition. Finally, these methods are summarized and trend of future development is addressed.
Spectral CT can produce basis materials with different X-ray energies. Subsequently, the generated basis materials can be used for qualitative and quantitative evaluation of tissue components and contrast agent distribution. This approach presents a superior ability to separate and identify imaging materials compared to traditional single-energy CT. Dual-energy spectrum technology is one of the most commonly used modes in spectrum CT, which plays an important role in clinical application. In this study, the decomposition methods of a basis material in the image domain of dual-energy spectrum CT were classified into two categories: two-material decomposition and multi-material decomposition. Finally, these methods are summarized and trend of future development is addressed.
14
2008, 17(1): 14-20.
Abstract：
Data modeling in reverse engineering is one of key technologies to realize RP. According to the 2D information of CT image, the edge contour was extracted by the image segmentation and binary image processing. Then the 3D CAD model was reconstructed. 3D physical model was made by reconstructing the 3D CAD model, converting into standard data for RP. It has wide application in the biomedicine domain. Based on the state of the study, the process of CT image reverse model and its application on RP were discussed.
Data modeling in reverse engineering is one of key technologies to realize RP. According to the 2D information of CT image, the edge contour was extracted by the image segmentation and binary image processing. Then the 3D CAD model was reconstructed. 3D physical model was made by reconstructing the 3D CAD model, converting into standard data for RP. It has wide application in the biomedicine domain. Based on the state of the study, the process of CT image reverse model and its application on RP were discussed.
15
2008, 17(1): 1-6.
Abstract：
In X-ray Diffraction Enhanced Imaging (DEI), the extinction contrast in peak CT mode can intensify the boundary of the object, and effectively raise the special resolution of the tomographic image. In this article, a definite physical explanation is given to this intensifying effect. By theoretic calculating and BSRF experimental data processing, it is demonstrated that this extinction contrast leads in CT image a fictitious one-pixel wide round ring with a very high mass density, and thus intensifies the image of edges of the round object.
In X-ray Diffraction Enhanced Imaging (DEI), the extinction contrast in peak CT mode can intensify the boundary of the object, and effectively raise the special resolution of the tomographic image. In this article, a definite physical explanation is given to this intensifying effect. By theoretic calculating and BSRF experimental data processing, it is demonstrated that this extinction contrast leads in CT image a fictitious one-pixel wide round ring with a very high mass density, and thus intensifies the image of edges of the round object.
16
2008, 17(1): 41-49.
Abstract：
With the fast development of the CT technology, real-time data acquiring and fast image reconstruction as a advanced capability in a Cone-beam CT system are more frequenfly requested. Therefore to transfer projection data from the detector unit to the computing unit in a fast and stable way becomes one of the key points in today's design of CT systems. In this paper we proposed a high speed data transmission solution based on Ethernet interface and Linux OS in which a transfer caching system is introduced. Test results show that such application has significant merits in solving the data loss problem while transferring from CT sampling module to the PC. Being with a low cost yet high stability and efficiency, it can be practically useful to the similar fast data acquiring system for image reconstruction.
With the fast development of the CT technology, real-time data acquiring and fast image reconstruction as a advanced capability in a Cone-beam CT system are more frequenfly requested. Therefore to transfer projection data from the detector unit to the computing unit in a fast and stable way becomes one of the key points in today's design of CT systems. In this paper we proposed a high speed data transmission solution based on Ethernet interface and Linux OS in which a transfer caching system is introduced. Test results show that such application has significant merits in solving the data loss problem while transferring from CT sampling module to the PC. Being with a low cost yet high stability and efficiency, it can be practically useful to the similar fast data acquiring system for image reconstruction.
17
2008, 17(2): 34-39.
Abstract：
In this paper, a novel wideband microstrip-fed monopole antenna with a size of only 24 mm×31.7 mm×1.6 mm is studied by the method of moment based on the two-level hi-conjugate gradient-fast Fourier transform method. The antenna has a wide bandwidth ranging from 3.1 GHz to 11 GHz for Sn11〈-10dB (S11 denotes the return losses). Details of the proposed antenna design approach and measured results are presented and discussed, which can be used for Ultra-wideband applications in the area of breast cancer imaging.
In this paper, a novel wideband microstrip-fed monopole antenna with a size of only 24 mm×31.7 mm×1.6 mm is studied by the method of moment based on the two-level hi-conjugate gradient-fast Fourier transform method. The antenna has a wide bandwidth ranging from 3.1 GHz to 11 GHz for Sn11〈-10dB (S11 denotes the return losses). Details of the proposed antenna design approach and measured results are presented and discussed, which can be used for Ultra-wideband applications in the area of breast cancer imaging.
18
2008, 17(1): 7-13.
Abstract：
Large pitch was used to speed up scanning in helical cone-beam CT, but its reconstruction remains a challenging problem. The Single-Slice ReBinning method (SSRB), proposed by Noo et al, can obtain high image quality at large pitch, but artifacts appear when pitch is too large for given detector. In this paper, a new approximate reconstruction scheme, i.e. Improved Single-Slice ReBinning method (ISSRB) is described. It modified the key rebinning step of SSRB. Theoretical considerations and reconstruction of simulation data are presented in comparison to SSRB in the paper. Results show that the pitch of proposed method is (1+tan2δ) times larger than that of SSRB for given detector size, and the reconstruction image quality is comparable or even better.
Large pitch was used to speed up scanning in helical cone-beam CT, but its reconstruction remains a challenging problem. The Single-Slice ReBinning method (SSRB), proposed by Noo et al, can obtain high image quality at large pitch, but artifacts appear when pitch is too large for given detector. In this paper, a new approximate reconstruction scheme, i.e. Improved Single-Slice ReBinning method (ISSRB) is described. It modified the key rebinning step of SSRB. Theoretical considerations and reconstruction of simulation data are presented in comparison to SSRB in the paper. Results show that the pitch of proposed method is (1+tan2δ) times larger than that of SSRB for given detector size, and the reconstruction image quality is comparable or even better.
19
Abstract：
To match the three dimension digital model and the CAD model, a new method is proposed, which consists of the surrounding box -based initial registration and the float data coded adaptive genetic algorithm-based accuracy registration. The initial registration can ensure the ranges of the spatial transform parameters for the accuracy registration. In the accuracy registration, the goal function is constructed by the method of the least squares. In order to overcome the premature convergence, an index that is related with the diversity of the population is defined. The index is used to define the crossover operator and mutation operator in the genetic algorithm, and to adjust the probabilities of the crossover and mutation adaptively. The result showed that the method can properly match the three dimension digital model and the CAD model, and the algorithm is steady and reliable.
To match the three dimension digital model and the CAD model, a new method is proposed, which consists of the surrounding box -based initial registration and the float data coded adaptive genetic algorithm-based accuracy registration. The initial registration can ensure the ranges of the spatial transform parameters for the accuracy registration. In the accuracy registration, the goal function is constructed by the method of the least squares. In order to overcome the premature convergence, an index that is related with the diversity of the population is defined. The index is used to define the crossover operator and mutation operator in the genetic algorithm, and to adjust the probabilities of the crossover and mutation adaptively. The result showed that the method can properly match the three dimension digital model and the CAD model, and the algorithm is steady and reliable.
20
2010, 19(1): 105-110.
Abstract：
In this paper according to the basic principle and structure,CT on spiral CT machine slip ring types,structure and working principle of the spiral CT through actual use machine slip ring properties and the application effect,advantages and disadvantages of CT slip ring,maintenance,from actual conditions,maintenance methods,steps and matters needing attention for design,manufacture,use and maintenance,and provide useful help.
In this paper according to the basic principle and structure,CT on spiral CT machine slip ring types,structure and working principle of the spiral CT through actual use machine slip ring properties and the application effect,advantages and disadvantages of CT slip ring,maintenance,from actual conditions,maintenance methods,steps and matters needing attention for design,manufacture,use and maintenance,and provide useful help.
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