Ultrafast quasi-three-dimensional imaging

Understanding laser induced ultrafast processes with complex three-dimensional(3D)geometries and extreme property evolution offers a unique opportunity to explore novel physical phenomena and to overcome the manufacturing limitations.Ultrafast imaging offers exceptional spatiotemporal resolution and thus has been considered an effective tool.However,in conventional single-view imaging techniques,3D information is projected on a two-dimensional plane,which leads to significant information loss that is detrimental to understanding the full ultrafast process.Here,we propose a quasi-3D imaging method to describe the ultrafast process and further analyze spatial asymmetries of laser induced plasma.Orthogonally polarized laser pulses are adopted to illuminate reflection-transmission views,and binarization techniques are employed to extract contours,forming the corresponding two-dimensional matrix.By rotating and multiplying the two-dimensional contour matrices obtained from the dual views,a quasi-3D image can be reconstructed.This successfully reveals dual-phase transition mechanisms and elucidates the diffraction phenomena occurring outside the plasma.Furthermore,the quasi-3D image confirms the spatial asymmetries of the picosecond plasma,which is difficult to achieve with two-dimensional images.Our findings demonstrate that quasi-3D imaging not only offers a more comprehensive understanding of plasma dynamics than previous imaging methods,but also has wide potential in revealing various complex ultrafast phenomena in related fields including strong-field physics,fluid dynamics,and cutting-edge manufacturing.

Terahertz Three-Dimensional Imaging Based on Computed Tomography with Photonics-Based Noise Source

Computed tomography has been proven to be useful for non-destructive inspection of structures and materials. We build a three-dimensional imaging system with the photonically generated incoherent noise source and the Schottky barrier diode detector in the terahertz frequency band （90–140GHz）. Based on the computed tomography technique, the three-dimensional image of a ceramic sample is reconstructed successfully by stacking the slices at different heights. The imaging results not only indicate the ability of terahertz wave in the non-invasive sensing and non-destructive inspection applications, but also prove the effectiveness and superiority of the uni-traveling-carrier photodiode as a terahertz source in the imaging applications.

Three-dimensional Imaging of Multi-slice Spiral CT in Bronchial Artery Correlative Study on Blood Supply of Central Lung Cancer and Its Clinical Significance

Objective: To evaluate three-dimensional bronchial artery imaging charactersin central lung cancer and applied values with multi-slice spiral CT (MSCT) to provide theoreticalevidence on blood supply and intervention therapy. Methods: Eighteen patients with central lungcancer underwent MSCT with real time helical thin-slice CT scanning. Three-dimensional bronchialartery reconstruction was done at the console work-station. The space anatomical characters ofbronchial artery were observed through different rotations. Results: For 6 cases, thethree-dimensional images of bronchial artery (33.33%) could exactly show the origins, the routes(lung inner segment and mediatism segment) and the diameters of bronchial arteries. Vision rate ofbronchial arteries was the highest in pulmonary artery stricture and truncation groups, and thevessels' diameter became larger apparently. These characters demonstrated blood supply of this kindof central lung cancer come from bronchial artery. Volume rendering images were the best ones amongthree-dimensional images. Conclusion: Three-dimensional imaging with MSCT in bronchial artery canreveal the anatomical characters of bronchial artery and provide theoretical evidence on bloodsupply and intervention therapy of central lung cancer.

Sparse three-dimensional imaging for forward-looking array SAR using spatial continuity

For forward-looking array synthetic aperture radar(FASAR),the scattering intensity of ground scatterers fluctuates greatly since there are kinds of vegetations and topography on the surface of the ground,and thus the signal-to-noise ratio(SNR)of its echo signals corresponding to different vegetations and topography also varies obviously.Owing to the reason known to all,the performance of the sparse reconstruction of compressed sensing(CS)becomes worse in the case of lower SNR,and the quality of the sparse three-dimensional imaging for FASAR would be affected significantly in the practical application.In this paper,the spatial continuity of the ground scatterers is introduced to the sparse recovery algorithm of CS in the threedimensional imaging for FASAR,in which the weighted least square method of the cubic interpolation is used to filter out the bad and isolated scatterer.The simulation results show that the proposed method can realize the sparse three-dimensional imaging of FASAR more effectively in the case of low SNR.

Three-dimensional imaging identified the accessory bile duct in a patient with cholangiocarcinoma

The development of diagnostic imaging technology, such as multidetector computed tomography(MDCT) and magnetic resonance cholangiopancreatography(MRCP), has made it possible to obtain detailed images of the bile duct. Recent reports have indicated that a 3-dimensional(3D) reconstructed imaging system would be useful for understanding the liver anatomy before surgery. We have investigated a novel method that fuses MDCT and MRCP images. This novel system easily made it possible to detect the anatomical relationship between the vessels and bile duct in the portal hepatis. In this report, we describe a very rare case of extrahepatic cholangiocarcinoma associated with an accessory bile duct from the caudate lobe connecting with the intrapancreatic bile duct. We were unable to preoperatively detect this accessory bile duct using MDCT and MRCP. However, prior to the second operation, we were able to clearly visualise the injured accessory bile duct using our novel 3D imaging modality. In thisreport, we suggest that this imaging technique can be considered a novel and useful modality for understanding the anatomy of the portal hepatis, including the hilar bile duct.

Role of three-dimensional imaging integration in atrial fibrillation ablation

Atrial fibrillation is the most common arrhythmia and in symptomatic patients with a drug-refractory form,catheter ablation aimed at electrically disconnecting the pulmonary veins(PVs) has proved more effective than use of antiarrhythmic drugs in maintaining sinus rhythm during follow-up.On the other hand,this ablation procedure is complex,requires specific training and adequate clinical experience.A main challenge is represented by the need for accurate sequential positioning of the ablation catheter around each veno-atrial junction to deliver point-by-point radiofrequency energy applications in order to achieve complete and persistent electrical disconnection of the PVs.Imaging integration is a new technology that enables guidance during this procedure by showing a three-dimensional,pre-acquired computed tomography or magnetic resonance image and the relative real-time position of the ablation catheter on the screen of the electroanatomic system.Reports in the literature suggest that imaging integration provides accurate visual information with improvement in the procedure parameters and/or clinical outcomes of the procedure.

Three-dimensional imaging of the uterus:The value of the coronal plane

Advent in three-dimensional(3D) imaging technology has seen 3D ultrasound establish itself as a useful adjunct complementary to traditional two-dimensional imaging of the female pelvis. This advantage largely arises from its ability to reconstruct the coronal plane of the uterus, which allows further delineation of many gynecological disorders. 3D imaging of the uterus is now the preferred imaging modality for assessing congenital uterine anomalies and intrauterine device localization. Newer indications include the diagnosis of adenomyosis. It can also add invaluable information to delineate other endometrial and myometrial pathology such as fibroids and endometrial polyps.

Clinical value of CT three-dimensional imaging in diagnosing gastrointestinal tract diseases

AIM： To discuss the clinical value of CT three-dimensional （3-D） imaging in diagnosing gastrointestinal tract diseases.METHODS： Three-D imaging findings of 52 patients were retrospectively analyzed. Three-D imaging methods included shaded surface display （SSD）, volume rendering （VR）, virtual endoscopy （VE） and multiplanar reformatting （MPR）. The diagnosis results of CT 3-D were evaluated by comparison with those of endoscopy and/or surgical finding.RESULTS： Fifty-two patients with gastrointestinal tract diseases were diagnosed by CT 3-D imaging, of whom 50 cases were correctly diagnosed and 2 were misdiagnosed. There were 33 cases of gastric diseases （27 with carcinoma, 5 with peptic ulcer and 1 with leiomyoma） and 19 large intestinal diseases （10 with colon carcinoma, 2 with carcinoma of the rectum, 5 with colon polypus and 2 with tuberculosis of the ileocecal junction）. Twenty-two cases with prominent lesions （9 with subsequent hollow lesions）, 20 with stenosis of cavity （8 with concomitant prominent lesions） and 10 with hollow lesions （5 with concomitant prominent lesions） were shown in 3-D images. The minimal lesion shown was 1.0 cm × 0.8 cm × 0.5 cm.CONCLUSION： CT 3-D imaging, a non-invasive examination without pain, can display clearly and directly the lesions of gastrointestinal tract with accurate location and high diagnosis accuracy. It is an important complementary technique to endoscopy.

CROSS-TRACK THREE APERTURES MILLIMETER WAVE SAR SIDE-LOOKING THREE-DIMENSIONAL IMAGING

The airborne cross-track three apertures MilliMeter Wave (MMW) Synthetic Aperture Radar (SAR) side-looking three-Dimensional (3D) imaging is investigated in this paper. Three apertures are distributed along the cross-track direction, and three virtual phase centers will be obtained through one-input and three-output. These three virtual phase centers form a sparse array which can be used to obtain the cross-track resolution. Because the cross-track array is short, the cross-track resolution is low. When the system works in side-looking mode, the cross-track resolution and height resolution will be coupling, and the low cross-track resolution will partly be transformed into the height uncertainty. The beam pattern of the real aperture is used as a weight to improve the Peak to SideLobe Ratio (PSLR) and Integrated SideLobe Ratio (ISLR) of the cross-track sparse array. In order to suppress the high cross-track sidelobes, a weighting preprocessing method is proposed. The 3D images of a point target and a simulation scene are achieved to verify the feasibility of the proposed method. And the imaging result of the real data obtained by the cross-track three-baseline MMW InSAR prototype is presented as a beneficial attempt.

Three-dimensional imaging reconstruction of the kidney’s anatomy for a tailored minimally invasive partial nephrectomy:A pilot study

Objective:The aim of the study was to evaluate three-dimensional virtual models(3DVMs)usefulness in the intraoperative assistance of minimally-invasive partial nephrectomy in highly complex renal tumors.Methods:At our institution cT1-2N0M0 all renal masses with Preoperative Aspects and Dimensions Used for an Anatomical classification score≥10 treated with minimally-invasive partial nephrectomy were considered for the present study.For inclusion a baseline contrast-enhanced computed tomography in order to obtain 3DVMs,the baseline and postoperative serum creatinine as well as estimated glomerular filtration rate values were needed.These patients,in which 3DVMs were used to assist the surgeon in the planning and intraoperative guidance,were then compared with a control group of patients who underwent minimally-invasive partial nephrectomy with the same renal function assessments,but without 3DVMs.Multivariable logistic regression models were used to predict the margin,ischemia,and complication score achievement.Results:Overall,79 patients met the inclusion criteria and were compared with 143 complex renal masses without 3DVM assistance.The 3DVM group showed better postoperative outcomes in terms of baseline-weighted differential estimated glomerular filtration rate(-17.7%vs.-22.2%,p=0.03),postoperative complications(16.5%vs.23.1%,p=0.03),and major complications(Clavien Dindo>III,2.5%vs.5.6%,p=0.03).At multivariable logistic regression 3DVM assistance independently predicted higher rates of successful partial nephrectomy(odds ratio:1.42,p=0.03).Conclusion:3DVMs represent a useful tool to plan a tailored surgical approach in case of surgically complex masses.They can be used in different ways,matching the surgeon's needs from the planning phase to the demolitive and reconstructive phase,leading towards maximum safety and efficacy outcomes.

Passive ranging and a three-dimensional imaging system through wavefront coding

A single-image passive ranging and three-dimensional(3 D)imaging system with chiral phase encoding was proposed in 2011[Opt.Lett.36,115(2011)].A new theoretical analysis of the system in space domain is presented in this paper.We deduce the analytic relationships between the object distance and the point spread function,and between the object distance and the encoded image,respectively.Both the point spread function and the processed spectrum of the encoded image have two spots,which will rotate with the variation of the object distance.Then the depth map is extracted from the encoded image and it can be used to set up 3 D images.The theoretical analysis is verified by a wavefront coding system with a chiral phase which is generated by a phase-only liquid-crystal spatial light modulator.The phase generated by the liquid-crystal spatial light modulator is more flexible than the fixed phase mask and can be adjusted in real time.It is especially suitable for observing the object with a large depth of field.

The Importance of Three-Dimensional Imaging from CBCT in Elucidating a Well-Defined Radiolucency Image within the Maxillary Sinus: A Case Report

This study describes a case of antral septum with alveolar process extension that is identified using cone-beam computed tomography (CBCT). Periapical radiolucency was observed in the maxillary sinus, and clinical and radiographic examinations ruled out the possibility of odontogenic lesions. CBCT was performed to elucidate the radiolucency identified using periapical radiography. A 3-D image indicated that the maxillary sinus extended into the alveolar process toward the palatal cortical bone in the region of the maxillary right first molar, as well as an antral septum extending from the inferior and lateral wall of the right maxillary sinus. CBCT is an important tool for use in dental practice because CBCT images reveal the entire volume of the maxillary sinus and allow for identification of patient anatomy and anatomical variations, which is essential for planning appropriate surgical interventions.

Generative deep-learning-embedded asynchronous structured light for three-dimensional imaging

Three-dimensional(3D)imaging with structured light is crucial in diverse scenarios,ranging from intelligent manufacturing and medicine to entertainment.However,current structured light methods rely on projector-camera synchronization,limiting the use of affordable imaging devices and their consumer applications.In this work,we introduce an asynchronous structured light imaging approach based on generative deep neural networks to relax the synchronization constraint,accomplishing the challenges of fringe pattern aliasing,without relying on any a priori constraint of the projection system.To overcome this need,we propose a generative deep neural network with U-Net-like encoder-decoder architecture to learn the underlying fringe features directly by exploring the intrinsic prior principles in the fringe pattern aliasing.We train within an adversarial learning framework and supervise the network training via a statisticsinformed loss function.We demonstrate that by evaluating the performance on fields of intensity,phase,and 3D reconstruction.It is shown that the trained network can separate aliased fringe patterns for producing comparable results with the synchronous one:the absolute error is no greater than 8μm,and the standard deviation does not exceed 3μm.Evaluation results on multiple objects and pattern types show it could be generalized for any asynchronous structured light scene.

Generic and flexible self-correction method for nonlinearity-induced phase error in three-dimensional imaging

In three-dimensional imaging employing phase-shifting profilometry(PSP), the nonlinear response of projector and camera makes the fringe gray distribution non-sinusoidal, which further leads to phase error. Although the double 3-step phaseshifting method is simple and effective, it needs to add an additional set of fringe sequences, which reduces the measurement efficiency. To this end, this paper introduces a generic and flexible self-correction method for nonlinearity-induced phase error.First, according to the nonlinearity-induced phase error model, we introduce an additional wrapped phase with a phase difference of π/3. The error waveform of the two wrapped phases is opposite but not coincident. Then, we introduce an estimation algorithm for the additional wrapped phase offset. Finally, we fuse the two wrapped phases to correct the phase error. Experiments confirm that the root mean squared error of the proposed method is 64.1% lower than that of the traditional method and 13.3% lower than that of the Hilbert transform method. The proposed method does not require any additional fringes or hardware assistance and can be easily extended to 4-step or 5-step PSP.

Development of a toroidal soft x-ray imaging system and application for investigating three-dimensional plasma on J-TEXT

A toroidal soft x-ray imaging(T-SXRI)system has been developed to investigate threedimensional(3D)plasma physics on J-TEXT.This T-SXRI system consists of three sets of SXR arrays.Two sets are newly developed and located on the vacuum chamber wall at toroidal positionsφof 126.4°and 272.6°,respectively,while one set was established previously atφ=65.50.Each set of SXR arrays consists of three arrays viewing the plasma poloidally,and hence can be used separately to obtain SXR images via the tomographic method.The sawtooth precursor oscillations are measured by T-SXRI,and the corresponding images of perturbative SXR signals are successfully reconstructed at these three toroidal positions,hence providing measurement of the 3D structure of precursor oscillations.The observed 3D structure is consistent with the helical structure of the m/n=1/1 mode.The experimental observation confirms that the T-SXRI system is able to observe 3D structures in the J-TEXT plasma.

Advances and prospects in SAR microwave vision three-dimensional imaging

Synthetic Aperture Radar three-dimensional(3D)imaging enables the acquisition of more comprehensive information,making it a recent hotspot in radar imaging.Traditional 3D imaging methods have evolved from 2D and interferometric imaging,combining elevation aperture extension with signal processing techniques.Limitations such as long acquisition or complex system from its imaging mechanism restrict its application.In recent years,rapid development of artificial intelligence has led to a swift advancement in radar,injecting new vitality into SAR 3D imaging.SAR microwave vision 3D imaging theory,which is built upon advanced technologies,has emerged as a new interdisciplinary field for radar imaging.This paper reviews SAR 3D imaging’s history and present situation,and introduces SAR microwave vision.We establish a theoretical framework covering representation models,computational models,processing paradigms and evaluation systems.Additionally,our research progress in this area is discussed,along with future prospects for SAR microwave vision 3D imaging.

Five-view three-dimensional reconstructionfor ultrafast dynamic imaging of pulsedradiation sources

Multiaxial neutron/x-ray imaging and three-dimensional (3D) reconstruction techniques play a crucial role in gaining valuable insights intothe generation and evolution mechanisms of pulsed radiation sources. Owing to the short emission time (∼200 ns) and drastic changes of thepulsed radiation source, it is necessary to acquire projection data within a few nanoseconds in order to achieve clear computed tomography3D imaging. As a consequence, projection data that can be used for computed tomography image reconstruction at a certain moment are oftenavailable for only a few angles. Traditional algorithms employed in the process of reconstructing 3D images with extremely incomplete datamay introduce significant distortions and artifacts into the final image. In this paper, we propose an iterative image reconstruction methodusing cylindrical harmonic decomposition and a self-supervised denoising network algorithm based on the deep image prior method. Weaugment the prior information with a 2D total variation prior and a 3D deep image prior. Single-wire Z-pinch imaging experiments have beencarried out at Qin-1 facility in five views and four frames, with a time resolution of 3 ns for each frame and a time interval of 40 ns betweenadjacent frames. Both numerical simulations and experiments verify that our proposed algorithm can achieve high-quality reconstructionresults and obtain the 3D intensity distribution and evolution of extreme ultraviolet and soft x-ray emission from plasma.

Single exposure passive three-dimensional information reconstruction based on an ordinary imaging system

Existing three-dimensional(3D) imaging technologies have issues such as requiring active illumination, multiple exposures, or coding modulation. We propose a passive single 3D imaging method based on an ordinary imaging system.Using the point spread function of the imaging system to realize the non-coding measurement on the target, the full-focus images and depth information of the 3D target can be extracted from a single two-dimensional(2D) image through the compressed sensing algorithm. Simulation and experiments show that this approach can complete passive 3D imaging based on an ordinary imaging system without any coding operations. This method can achieve millimeter-level vertical resolution under single exposure conditions and has the potential for real-time dynamic 3D imaging. It improves the efficiency of 3D information detection, reduces the complexity of the imaging system, and may be of considerable value to the field of computer vision and other related applications.

Using restored two-dimensional X-ray images to reconstruct the three-dimensional magnetopause

Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray imaging.However,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the magnetopause.The analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration models.This makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical models.We propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the magnetosphere.The idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch estimator.The Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the estimator.Experimental results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural similarity.The restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving the reconstruction results.Hence,the proposed technology may be feasible for processing SXI-simulated observation images.

GPU-accelerated three-dimensional reconstruction method of the Compton camera and its application in radionuclide imaging

A novel and fast three-dimensional reconstruction method for a Compton camera and its performance in radionuclide imaging is proposed and analyzed in this study. The conical surface sampling back-projection method with scattering angle correction(CSS-BP-SC) can quickly perform the back-projection process of the Compton cone and can be used to precompute the list-mode maximum likelihood expectation maximization(LM-MLEM). A dedicated parallel architecture was designed for the graphics processing unit acceleration of the back-projection and iteration stage of the CSS-BP-SC-based LM-MLEM. The imaging results of the two-point source Monte Carlo(MC) simulation demonstrate that by analyzing the full width at half maximum along the three coordinate axes, the CSS-BP-SC-based LM-MLEM can obtain imaging results comparable to those of the traditional reconstruction algorithm, that is, the simple back-projection-based LM-MLEM. The imaging results of the mouse phantom MC simulation and experiment demonstrate that the reconstruction results obtained by the proposed method sufficiently coincide with the set radioactivity distribution, and the speed increased by more than 664 times compared to the traditional reconstruction algorithm in the mouse phantom experiment. The proposed method will further advance the imaging applications of Compton cameras.