Dose estimation and quality control in computed tomography (CT) scanners are useful in controlling the dose of radiation given to patients while tests are carried out. The study was performed in a 16-slice Computed To...Dose estimation and quality control in computed tomography (CT) scanners are useful in controlling the dose of radiation given to patients while tests are carried out. The study was performed in a 16-slice Computed Tomography (CT) system of LightSpeed RT16 Xtra CT scanner. Quality control was done using a vendor-provided QA Phantom, and the six aspects of image quality were measured. For CT dosimetry, Computed Tomography Dose index volume (CTDIvol) was performed using Computed Tomography Dose Index (CTDI) Phantom. CTDI Phantom consists of three parts: Pediatric Head, Adult Head, and Adult Body Phantom. A 10 cm long pencil ion chamber DCT-10 was used to measure the dose at different positions inside the CTDI Phantom. Data were collected using MagicMax Universal software. For dose estimation of the CTDIvol Report of AAPM Task Group, 96 and 111 formalisms were used. For Pediatric Head, Adult Head, and Adult Body Phantom the measured CIDIvol was 61.04 mGy, 48.11 mGy, and 18.08 mGy respectively. The study has shown deviations of 7%, 15%, and 19% between estimated and console-displayed doses for Pediatric Head, Adult Head, and Adult Body scan techniques respectively. The six aspects of image quality measured by QA Phantom were found to be compatible with the specifications of the machine and CTDIvol measured by CTDI Phantom were found within a tolerance limit of ±20%. Hence, the QC and dosimetry of the mentioned machine are within the limit.展开更多
To expand scanning area and attack range without changing the inner structure of intelligent warhead, a new arrangement mode of the scanner for intelligent mine is proposed. The required coordinate systems are es...To expand scanning area and attack range without changing the inner structure of intelligent warhead, a new arrangement mode of the scanner for intelligent mine is proposed. The required coordinate systems are established firstly on the basis of advanced dynamics principle. and the exterior ballistics equations are deduced. Then the equations of scanning trails are established by the method of space analytic geometry. To get the scanning trails. the differential equations are transformed into discrete simulation model using the algorithm of fourth order Runge-Kutta and then are simulated using Matlab. Compared with the scanning trails obtained by the traditional layout of scanner, the scanning trails obtained by the proposed layout of scanner has larger horizontal range of scanning circle and bigger trarget acquisition probability. Therefore, the new arrangement mode of the scanner for intelligent mine can increase attack range.展开更多
<b>Introduction:</b> Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners...<b>Introduction:</b> Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners. Studies assessing the accuracy of digital models have shown digital models to be valid, clinically acceptable, and more quickly obtainable. With the advent of new scanners with better scanning technology researches are necessary to evaluate their accuracy and reliability. <b>Aim of Study:</b> To evaluate the diagnostic accuracy of 3D digital models obtained through intraoral and extraoral scanning modalities to the reference gold standard plaster model. <b>Material & Methods:</b> Twenty-four adult male and female subjects were randomly selected for this study. The intraoral scanners evaluated in this study were Sirona (CEREC Omnicam) and 3 shape (TRIOS 3), while the laboratory scanners used were Sirona (inEos X5), and 3 shape (D850). Intra-oral scanning of the subjects and extra-oral scanning of their alginate impressions, plaster models of the alginate impression, rubber base impression, and plaster model of their rubber base impression were done. Linear dental measurements included intermolar width, interpremolar width, intercanine width, mesiodistal width of the 1<sup>st</sup> permanent molar, 1<sup>st</sup> premolar, canine and central incisor and arch width. All data were collected, tabulated and subjected to statistical analysis. <b>Results:</b> Small differences between the plaster and digital models were observed. Intra-observer reliability analysis for 14 out of the 16 measurements showed that all variables exhibited good to excellent reliability. <b>Conclusions: </b>There was no difference between the digitization using the intraoral scanner or the laboratory scanner. The most accurate digitization technique was the 3 Shape laboratory scanner of the cast of the alginate impression. The inEos X5 showed the highest error of digitization of the alginate and rubber base impressions.展开更多
The paper approaches the problem of the command functions of galvanometer-based scanners （GS） that are necessary to produce the linear plus parabolic scanning function of the GS, which we have proved previously to p...The paper approaches the problem of the command functions of galvanometer-based scanners （GS） that are necessary to produce the linear plus parabolic scanning function of the GS, which we have proved previously to produce the highest possible duty cycle （i.e., time efficiency） of the device. We have completed this theoretical aspect （which contradicted what has been stated previously in the literature, where it has been considered that the linear plus sinusoidal scanning function was the best） with the experimental study of the most used scanning functions of the GSs （sawtooth, sinusoidal and triangular）, with applications in biomedical imaging, in particular in optical coherence tomography, demonstrating that the triangular function is always the best one to be applied, from both an optical and a mechanical point of view. In the present study the input voltage/command function which should be applied to the GS to produce the desired triangular scanning function （with controlled non-linearity for the fastest possible stop-and-turn portions） was determined analytically, in relationship with the active torque that drives the device. This command function is analyzed with regard to the specific, respectively required parameters of the GS： natural frequency and damping factor, respectively scan speed and amplitude. The modeling in an open loop control structure of the GS is finally discussed as a trade-off between using the highest possible duty cycle and minimizing the maximum peaks of the input voltage.展开更多
Feature extraction of range images provided by ranging sensor is a key issue of pattern recognition. To automatically extract the environmental feature sensed by a 2D ranging sensor laser scanner, an improved method b...Feature extraction of range images provided by ranging sensor is a key issue of pattern recognition. To automatically extract the environmental feature sensed by a 2D ranging sensor laser scanner, an improved method based on genetic clustering VGA-clustering is presented. By integrating the spatial neighbouring information of range data into fuzzy clustering algorithm, a weighted fuzzy clustering algorithm （WFCA） instead of standard clustering algorithm is introduced to realize feature extraction of laser scanner. Aimed at the unknown clustering number in advance, several validation index functions are used to estimate the validity of different clustering algorithms and one validation index is selected as the fitness function of genetic algorithm so as to determine the accurate clustering number automatically. At the same time, an improved genetic algorithm IVGA on the basis of VGA is proposed to solve the local optimum of clustering algorithm, which is implemented by increasing the population diversity and improving the genetic operators of elitist rule to enhance the local search capacity and to quicken the convergence speed. By the comparison with other algorithms, the effectiveness of the algorithm introduced is demonstrated.展开更多
In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structur...In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structured light measurement model based on a galvanometer scanner was proposed to obtain the 3D information of the workpiece. A height calibration method was proposed to further ensure measurement accuracy, so as to achieve accurate laser focusing. In-situ machining software was developed to realize time-saving and labor-saving 3D laser processing. The feasibility and practicability of this in-situ laser machining system were verified using specific cases. In comparison with the conventional line structured light measurement method, the proposed methods do not require light plane calibration, and do not need additional motion axes for 3D reconstruction;thus they provide technical and cost advantages. The insitu laser machining system realizes a simple operation process by integrating measurement and machining,which greatly reduces labor and time costs.展开更多
Marking arbitrary three-dimensional(3D) target curves on given objects with curved surface is required in many industrial fields, such as fabric prepreg placement in composite material part fabrication, product assemb...Marking arbitrary three-dimensional(3D) target curves on given objects with curved surface is required in many industrial fields, such as fabric prepreg placement in composite material part fabrication, product assembly, surface painting for decoration, etc. A shortcut to the solution of this intractable problem is proposed by utilizing a galvanometric laser scanner(GLS) with the aid of a camera. Without using the existing tedious GLS calibration procedures,the proposed method directly establishes a mapping between the 3D coordinates of the laser spots on the object surface and the control voltages of the scanner. A single-hidden layer feedforward neural network(SLFN) is employed to model the mapping. By projecting a dense grid of laser spots on the object to be marked and simultaneously taking only one image, the SLFN model is trained in minutes via a linear solving mechanism. Experiments demonstrate that the trained SLFN model has a good generalization performance for marking 3D target curves. The 3D laser marking errors on experimental objects are less than 0.5 mm. The proposed method is especially suitable for on-site use and can be conveniently extended to multiple GLSs for marking large complex objects.展开更多
Leaf normal distribution is an important structural characteristic of the forest canopy. Although terrestrial laser scanners（TLS） have potential for estimating canopy structural parameters, distinguishing between le...Leaf normal distribution is an important structural characteristic of the forest canopy. Although terrestrial laser scanners（TLS） have potential for estimating canopy structural parameters, distinguishing between leaves and nonphotosynthetic structures to retrieve the leaf normal has been challenging. We used here an approach to accurately retrieve the leaf normals of camphorwood（Cinnamomum camphora） using TLS point cloud data.First, nonphotosynthetic structures were filtered by using the curvature threshold of each point. Then, the point cloud data were segmented by a voxel method and clustered by a Gaussian mixture model in each voxel. Finally, the normal vector of each cluster was computed by principal component analysis to obtain the leaf normal distribution. We collected leaf inclination angles and estimated the distribution, which we compared with the retrieved leaf normal distribution. The correlation coefficient between measurements and obtained results was 0.96, indicating a good coincidence.展开更多
Objective To validate the performance of Mycob. T Stainer and Scanner(MTSS) for detecting acid-fast bacilli(AFB). Methods A total of 3,816 sputum samples from 1,515 tuberculosis(TB) suspects were tested at the Anhui P...Objective To validate the performance of Mycob. T Stainer and Scanner(MTSS) for detecting acid-fast bacilli(AFB). Methods A total of 3,816 sputum samples from 1,515 tuberculosis(TB) suspects were tested at the Anhui Provincial Chest Hospital and the Linyi People’s Hospital from April-August, 2016. Each specimen was placed on two smear slides. One slide was stained by the ziehl-neelsen(ZN) method to be read by conventional microscopy(CM). The other slide was stained and scanned by MTSS. All specimens were decontaminated with 4% NaO H, and then inoculated into solid culture. The performance of MTSS was assessed. Results MTSS produced higher average positivity rate(27.96%) as compared with the CM(26.83%). The overall sensitivity and specificity of MTSS were 78.9% and 93.9%, respectively. The sensitivity and specificity of CM was 77.4% and 95.0%, respectively. Conclusion MTSS exhibited a favorable performance in the detection of AFB. It may be an alternative to CM for screening TB.展开更多
文摘Dose estimation and quality control in computed tomography (CT) scanners are useful in controlling the dose of radiation given to patients while tests are carried out. The study was performed in a 16-slice Computed Tomography (CT) system of LightSpeed RT16 Xtra CT scanner. Quality control was done using a vendor-provided QA Phantom, and the six aspects of image quality were measured. For CT dosimetry, Computed Tomography Dose index volume (CTDIvol) was performed using Computed Tomography Dose Index (CTDI) Phantom. CTDI Phantom consists of three parts: Pediatric Head, Adult Head, and Adult Body Phantom. A 10 cm long pencil ion chamber DCT-10 was used to measure the dose at different positions inside the CTDI Phantom. Data were collected using MagicMax Universal software. For dose estimation of the CTDIvol Report of AAPM Task Group, 96 and 111 formalisms were used. For Pediatric Head, Adult Head, and Adult Body Phantom the measured CIDIvol was 61.04 mGy, 48.11 mGy, and 18.08 mGy respectively. The study has shown deviations of 7%, 15%, and 19% between estimated and console-displayed doses for Pediatric Head, Adult Head, and Adult Body scan techniques respectively. The six aspects of image quality measured by QA Phantom were found to be compatible with the specifications of the machine and CTDIvol measured by CTDI Phantom were found within a tolerance limit of ±20%. Hence, the QC and dosimetry of the mentioned machine are within the limit.
文摘To expand scanning area and attack range without changing the inner structure of intelligent warhead, a new arrangement mode of the scanner for intelligent mine is proposed. The required coordinate systems are established firstly on the basis of advanced dynamics principle. and the exterior ballistics equations are deduced. Then the equations of scanning trails are established by the method of space analytic geometry. To get the scanning trails. the differential equations are transformed into discrete simulation model using the algorithm of fourth order Runge-Kutta and then are simulated using Matlab. Compared with the scanning trails obtained by the traditional layout of scanner, the scanning trails obtained by the proposed layout of scanner has larger horizontal range of scanning circle and bigger trarget acquisition probability. Therefore, the new arrangement mode of the scanner for intelligent mine can increase attack range.
文摘<b>Introduction:</b> Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners. Studies assessing the accuracy of digital models have shown digital models to be valid, clinically acceptable, and more quickly obtainable. With the advent of new scanners with better scanning technology researches are necessary to evaluate their accuracy and reliability. <b>Aim of Study:</b> To evaluate the diagnostic accuracy of 3D digital models obtained through intraoral and extraoral scanning modalities to the reference gold standard plaster model. <b>Material & Methods:</b> Twenty-four adult male and female subjects were randomly selected for this study. The intraoral scanners evaluated in this study were Sirona (CEREC Omnicam) and 3 shape (TRIOS 3), while the laboratory scanners used were Sirona (inEos X5), and 3 shape (D850). Intra-oral scanning of the subjects and extra-oral scanning of their alginate impressions, plaster models of the alginate impression, rubber base impression, and plaster model of their rubber base impression were done. Linear dental measurements included intermolar width, interpremolar width, intercanine width, mesiodistal width of the 1<sup>st</sup> permanent molar, 1<sup>st</sup> premolar, canine and central incisor and arch width. All data were collected, tabulated and subjected to statistical analysis. <b>Results:</b> Small differences between the plaster and digital models were observed. Intra-observer reliability analysis for 14 out of the 16 measurements showed that all variables exhibited good to excellent reliability. <b>Conclusions: </b>There was no difference between the digitization using the intraoral scanner or the laboratory scanner. The most accurate digitization technique was the 3 Shape laboratory scanner of the cast of the alginate impression. The inEos X5 showed the highest error of digitization of the alginate and rubber base impressions.
基金the support of the US Department of State through Fulbright Scholar Grant 474/2009
文摘The paper approaches the problem of the command functions of galvanometer-based scanners （GS） that are necessary to produce the linear plus parabolic scanning function of the GS, which we have proved previously to produce the highest possible duty cycle （i.e., time efficiency） of the device. We have completed this theoretical aspect （which contradicted what has been stated previously in the literature, where it has been considered that the linear plus sinusoidal scanning function was the best） with the experimental study of the most used scanning functions of the GSs （sawtooth, sinusoidal and triangular）, with applications in biomedical imaging, in particular in optical coherence tomography, demonstrating that the triangular function is always the best one to be applied, from both an optical and a mechanical point of view. In the present study the input voltage/command function which should be applied to the GS to produce the desired triangular scanning function （with controlled non-linearity for the fastest possible stop-and-turn portions） was determined analytically, in relationship with the active torque that drives the device. This command function is analyzed with regard to the specific, respectively required parameters of the GS： natural frequency and damping factor, respectively scan speed and amplitude. The modeling in an open loop control structure of the GS is finally discussed as a trade-off between using the highest possible duty cycle and minimizing the maximum peaks of the input voltage.
基金the National Natural Science Foundation of China (60234030)the Natural Science Foundationof He’nan Educational Committee of China (2007520019, 2008B520015)Doctoral Foundation of Henan Polytechnic Universityof China (B050901, B2008-61)
文摘Feature extraction of range images provided by ranging sensor is a key issue of pattern recognition. To automatically extract the environmental feature sensed by a 2D ranging sensor laser scanner, an improved method based on genetic clustering VGA-clustering is presented. By integrating the spatial neighbouring information of range data into fuzzy clustering algorithm, a weighted fuzzy clustering algorithm （WFCA） instead of standard clustering algorithm is introduced to realize feature extraction of laser scanner. Aimed at the unknown clustering number in advance, several validation index functions are used to estimate the validity of different clustering algorithms and one validation index is selected as the fitness function of genetic algorithm so as to determine the accurate clustering number automatically. At the same time, an improved genetic algorithm IVGA on the basis of VGA is proposed to solve the local optimum of clustering algorithm, which is implemented by increasing the population diversity and improving the genetic operators of elitist rule to enhance the local search capacity and to quicken the convergence speed. By the comparison with other algorithms, the effectiveness of the algorithm introduced is demonstrated.
文摘In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structured light measurement model based on a galvanometer scanner was proposed to obtain the 3D information of the workpiece. A height calibration method was proposed to further ensure measurement accuracy, so as to achieve accurate laser focusing. In-situ machining software was developed to realize time-saving and labor-saving 3D laser processing. The feasibility and practicability of this in-situ laser machining system were verified using specific cases. In comparison with the conventional line structured light measurement method, the proposed methods do not require light plane calibration, and do not need additional motion axes for 3D reconstruction;thus they provide technical and cost advantages. The insitu laser machining system realizes a simple operation process by integrating measurement and machining,which greatly reduces labor and time costs.
基金partly supported by the National Natural Science Foundation of China (No. 51575276)
文摘Marking arbitrary three-dimensional(3D) target curves on given objects with curved surface is required in many industrial fields, such as fabric prepreg placement in composite material part fabrication, product assembly, surface painting for decoration, etc. A shortcut to the solution of this intractable problem is proposed by utilizing a galvanometric laser scanner(GLS) with the aid of a camera. Without using the existing tedious GLS calibration procedures,the proposed method directly establishes a mapping between the 3D coordinates of the laser spots on the object surface and the control voltages of the scanner. A single-hidden layer feedforward neural network(SLFN) is employed to model the mapping. By projecting a dense grid of laser spots on the object to be marked and simultaneously taking only one image, the SLFN model is trained in minutes via a linear solving mechanism. Experiments demonstrate that the trained SLFN model has a good generalization performance for marking 3D target curves. The 3D laser marking errors on experimental objects are less than 0.5 mm. The proposed method is especially suitable for on-site use and can be conveniently extended to multiple GLSs for marking large complex objects.
文摘Leaf normal distribution is an important structural characteristic of the forest canopy. Although terrestrial laser scanners（TLS） have potential for estimating canopy structural parameters, distinguishing between leaves and nonphotosynthetic structures to retrieve the leaf normal has been challenging. We used here an approach to accurately retrieve the leaf normals of camphorwood（Cinnamomum camphora） using TLS point cloud data.First, nonphotosynthetic structures were filtered by using the curvature threshold of each point. Then, the point cloud data were segmented by a voxel method and clustered by a Gaussian mixture model in each voxel. Finally, the normal vector of each cluster was computed by principal component analysis to obtain the leaf normal distribution. We collected leaf inclination angles and estimated the distribution, which we compared with the retrieved leaf normal distribution. The correlation coefficient between measurements and obtained results was 0.96, indicating a good coincidence.
基金supported by Chinese Anti-Tuberculosis Association[042016]
文摘Objective To validate the performance of Mycob. T Stainer and Scanner(MTSS) for detecting acid-fast bacilli(AFB). Methods A total of 3,816 sputum samples from 1,515 tuberculosis(TB) suspects were tested at the Anhui Provincial Chest Hospital and the Linyi People’s Hospital from April-August, 2016. Each specimen was placed on two smear slides. One slide was stained by the ziehl-neelsen(ZN) method to be read by conventional microscopy(CM). The other slide was stained and scanned by MTSS. All specimens were decontaminated with 4% NaO H, and then inoculated into solid culture. The performance of MTSS was assessed. Results MTSS produced higher average positivity rate(27.96%) as compared with the CM(26.83%). The overall sensitivity and specificity of MTSS were 78.9% and 93.9%, respectively. The sensitivity and specificity of CM was 77.4% and 95.0%, respectively. Conclusion MTSS exhibited a favorable performance in the detection of AFB. It may be an alternative to CM for screening TB.
