In cone-beam computed tomography （CBCT）, there are often cases where the size of the specimen is larger than the field of view （FOV） （referred to as over FOV-sized （OFS））. To acquire the complete projection da...In cone-beam computed tomography （CBCT）, there are often cases where the size of the specimen is larger than the field of view （FOV） （referred to as over FOV-sized （OFS））. To acquire the complete projection data for OFS objects, some scan modes have been developed for long objects and short but over-wide objects. However, these modes still cannot meet the requirements for both longitudinally long and transversely wide objects. In this paper, we propose a multiple helical scan mode and a corresponding reconstruction algorithm for both longitudinally long and transversely wide objects. The simulation results show that our model can deal with the problem and that the results are acceptable, while the OFS object is twice as long compared with the FOV in the same latitude.展开更多
Size-scalable X-ray scintillators with high transparency and robust photon yield allow for imaging large objects with greater precision and detail.Solution-processable scintillators,typically crafted from quantum dots...Size-scalable X-ray scintillators with high transparency and robust photon yield allow for imaging large objects with greater precision and detail.Solution-processable scintillators,typically crafted from quantum dots(QDs),are promising candidates for highly efficient scintillation applications.However,the restricted size and low transparency in QD-based scintillators lead to less efficient X-ray imaging for large objects requiring high resolution.Herein,we demonstrate a meter-scale ZnO QD scintillator with a visible range transmittance exceeding 96%,featuring bright singlet-triplet hybrid self-trapping excitons(STEs).The quantum yields(QYs)of singlet excitons and triplet excitons are 44.7%and 26.3%.Benefiting from a large Stokes shift and bright triplet excitons,the scintillator has a negligible self-absorption and elevated photon yields.Additionally,the scintillator exhibits exchange invariance,demonstrating identical optical performance upon exchanging the coordinates(r)of the QDs.Featuring bright singlet-triplet hybrid STEs and high transparency,the scintillator achieves high resolution X-ray imaging of 42-line pairs per millimeter(42 lp mm^(-1))at a meter scale.Moreover,demonstrations of 5000 cm^(2) X-ray imaging and real-time dynamic X-ray imaging are presented.The lowest detectable dose rate for X-ray detection is as low as 37.63±0.4 nGy s^(-1).This work presents a novel sizable and transparent scintillator with bright singlet-triplet hybrid STEs,showcasing their potential in high-resolution and sizable object X-ray imaging.展开更多
The simplification of 3D laser scanning point cloud is an important step of surface reconstruction and volume estimation of bulk grain in granary.This study presented an adaptive simplification algorithm based on part...The simplification of 3D laser scanning point cloud is an important step of surface reconstruction and volume estimation of bulk grain in granary.This study presented an adaptive simplification algorithm based on particle swarm optimization(PSO).It introduced PSO into the average distance method,a conventional simplification method.The basic idea of this algorithm was to adaptively determine the optimal point reducing intervals of scanning lines according to original point cloud density by PSO.By using the 3D point cloud scanned from bulk grain surface in granary,the proposed algorithm was validated.Compared with the average distance method,the proposed algorithm obtained more evenly distributed point set,smaller reduction ratio(6.96%)and higher volume estimation accuracy(relative error was less than 3‰).The 3D laser scanner(GSLS003,Jilin University and SkyViTech Co.,Ltd.,Hangzhou,China)used in this study could scan the complete picture of the grain surface in a granary in one time,so the acquired point cloud data do not have to be jointed.For the good simplification performance and capability of updating the reducing interval at any moment,the proposed algorithm and the 3D laser scanner could be used to realize online real-time measurement of stored bulk grain volume in granary.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB707701)the National High Technology Research and Development Program of China (Grant No. 2009AA012200)the National Nature Science Foundation of China(Grant No. 30970722)
文摘In cone-beam computed tomography （CBCT）, there are often cases where the size of the specimen is larger than the field of view （FOV） （referred to as over FOV-sized （OFS））. To acquire the complete projection data for OFS objects, some scan modes have been developed for long objects and short but over-wide objects. However, these modes still cannot meet the requirements for both longitudinally long and transversely wide objects. In this paper, we propose a multiple helical scan mode and a corresponding reconstruction algorithm for both longitudinally long and transversely wide objects. The simulation results show that our model can deal with the problem and that the results are acceptable, while the OFS object is twice as long compared with the FOV in the same latitude.
基金supported by the National Natural Science Foundation of China(Grant Nos.62075198,11974317,61804136)the Outstanding Youth Foundation of Henan(Grant nos.222300420087)S.-Y.S.acknowledges the support from the National Postdoctoral Program for Innovative Talents(Grant No.BX20240337).
文摘Size-scalable X-ray scintillators with high transparency and robust photon yield allow for imaging large objects with greater precision and detail.Solution-processable scintillators,typically crafted from quantum dots(QDs),are promising candidates for highly efficient scintillation applications.However,the restricted size and low transparency in QD-based scintillators lead to less efficient X-ray imaging for large objects requiring high resolution.Herein,we demonstrate a meter-scale ZnO QD scintillator with a visible range transmittance exceeding 96%,featuring bright singlet-triplet hybrid self-trapping excitons(STEs).The quantum yields(QYs)of singlet excitons and triplet excitons are 44.7%and 26.3%.Benefiting from a large Stokes shift and bright triplet excitons,the scintillator has a negligible self-absorption and elevated photon yields.Additionally,the scintillator exhibits exchange invariance,demonstrating identical optical performance upon exchanging the coordinates(r)of the QDs.Featuring bright singlet-triplet hybrid STEs and high transparency,the scintillator achieves high resolution X-ray imaging of 42-line pairs per millimeter(42 lp mm^(-1))at a meter scale.Moreover,demonstrations of 5000 cm^(2) X-ray imaging and real-time dynamic X-ray imaging are presented.The lowest detectable dose rate for X-ray detection is as low as 37.63±0.4 nGy s^(-1).This work presents a novel sizable and transparent scintillator with bright singlet-triplet hybrid STEs,showcasing their potential in high-resolution and sizable object X-ray imaging.
基金This work was financially supported by National Natural Science Foundation of China(No.50975121)Jilin Province Science and Technology Development Plan Item(No.20130522150JH)2013 Jilin Province Science Foundation for Post Doctorate Research(No.RB201361).
文摘The simplification of 3D laser scanning point cloud is an important step of surface reconstruction and volume estimation of bulk grain in granary.This study presented an adaptive simplification algorithm based on particle swarm optimization(PSO).It introduced PSO into the average distance method,a conventional simplification method.The basic idea of this algorithm was to adaptively determine the optimal point reducing intervals of scanning lines according to original point cloud density by PSO.By using the 3D point cloud scanned from bulk grain surface in granary,the proposed algorithm was validated.Compared with the average distance method,the proposed algorithm obtained more evenly distributed point set,smaller reduction ratio(6.96%)and higher volume estimation accuracy(relative error was less than 3‰).The 3D laser scanner(GSLS003,Jilin University and SkyViTech Co.,Ltd.,Hangzhou,China)used in this study could scan the complete picture of the grain surface in a granary in one time,so the acquired point cloud data do not have to be jointed.For the good simplification performance and capability of updating the reducing interval at any moment,the proposed algorithm and the 3D laser scanner could be used to realize online real-time measurement of stored bulk grain volume in granary.
