- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Optimization of Transmitter-Side Signal Rotations in the Presence of Laser Phase Noise
摘要： In this paper, we present a 1050-nm electrically pumped microelectromechanically tunable vertical cavity surface-emitting laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept-source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost and complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide-field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over 6 mm × 6 mm and 3 mm × 3 mm fields to show retinal vasculature and capillary structure near the fovea. These results demonstrate the feasibility of electrically pumped MEMS-VCSELs in ophthalmic instrumentation, the largest clinical application of OCT. In addition, we estimate that the 3 dB coherence length in air is 225 ± 51 m, far greater than required for ophthalmic SS-OCT and suggestive of other distance ranging applications.
关键词： Medical imaging,tunable lasers,optical coherence tomography,micro and nano opto-electromechanical systems (MOEMS),semiconductor lasers
更新于2025-09-23 15:21:01
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Automatic lung segmentation in low-dose chest CT scans using convolutional deep and wide network (CDWN)
摘要： Computed tomography (CT) imaging is the preferred imaging modality for diagnosing lung-related complaints. Automatic lung segmentation is the most common prerequisite to develop a computerized diagnosis system for analyzing chest CT images. In this paper, a convolutional deep and wide network (CDWN) is proposed to segment lung region from the chest CT scan for further medical diagnosis. Earlier lung segmentation techniques depend on handcrafted features, and their performance relies on the features considered for segmentation. The proposed model automatically segments the lung from complete CT scan in two laps: (1) learning the required ?lters to extract hierarchical feature representations at convolutional layers, (2) dense prediction with spatial features through learnable deconvolutional layers. The model has been trained and evaluated with low-dose chest CT scan images on LIDC-IDRI database. The proposed CDWN reaches the average Dice coef?cient of 0.95 and accuracy of 98% in segmenting the lung regions from 20 test images and maintains consistent results for all test images. The experimental results con?rm that the proposed approach achieves a superior performance compared to other state-of-the-art methods for lung segmentation.
关键词： Medical imaging,Image processing and analysis,Deep learning,Automatic lung segmentation,Convolutional neural network
更新于2025-09-23 15:21:01
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Implementation and validation of time-of-flight PET image reconstruction module for listmode and sinogram projection data in the STIR library
摘要： In this paper, we describe the implementation of support for Time-of-Flight (TOF) Positron Emission Tomography (PET) for both listmode and sinogram data in the open source Software for Tomographic Image Reconstruction (STIR). We provide validation and performance characterization using simulated data from the open source GATE Monte Carlo toolbox, with TOF configurations spanning from 81.2 to 209.6 ps. The coincidence detector resolution was corrected for the timing resolution deterioration due to the contribution of the crystal length. Comparison between the reconstruction of listmode and sinogram data demonstrated good agreement in both TOF and non-TOF cases in terms of relative absolute error. To reduce the reconstruction time, we assessed the truncation of the TOF kernel along Lines-of-Response (LOR). Rejection of LOR elements beyond four times the TOF standard deviation provides significant acceleration of ≈ 45% without compromising the image quality. Further narrowing of the kernel can provide extra time reduction but with the gradual introduction of error in the reconstructed images. As expected, TOF reconstruction performs better than non-TOF in terms of both Contrast-Recovery-Coefficient (CRC) and Signal-to-Noise ratio (SNR). CRC achieves convergence faster with TOF, at lower noise levels. SNR with TOF was superior for early iterations, but with quick deterioration. Higher timing resolution further improved reconstruction performance, while TOF bin mashing was shown to have only a small impact on reconstructed images.
关键词： Medical Imaging,Open-Source Software,Positron Emission Tomography,Monte Carlo,Computer Simulations,Time-of-Flight
更新于2025-09-23 15:19:57
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Visualization and quantification of eye tracking data for the evaluation of oculomotor function
摘要： Oculomotor dysfunction may originate from physical, physiological or psychological causes and may be a marker for schizophrenia or other disorders. Observational tests for oculomotor dysfunction are easy to administer, but are subjective and transient, and it is difficult to quantify deviations. To date, video-based eye tracking systems have not provided a contextual overview of gaze data that integrates the eye video recording with the stimulus and gaze data together with quantitative feedback of metrics in relation to typical values. A system was developed with an interactive timeline to allow the analyst to scroll through a recording frame-by-frame while comparing data from three different sources. The visual and integrated nature of the analysis allows localisation and quantification of saccadic under- and overshoots as well as determination of the frequency and amplitude of catch-up and anticipatory saccades. Clinicians will be able to apply their expertise to diagnose disorders based on abnormal patterns in the gaze plots. They can use the line charts to quantify deviations from benchmark values for reaction time, saccadic accuracy and smooth pursuit gain. A clinician can refer to the eye video at any time to confirm that observed deviations originated from gaze behaviour and not from systemic errors.
关键词： Computer science,Medical imaging
更新于2025-09-19 17:15:36
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[IEEE 2019 24th Microoptics Conference (MOC) - Toyama, Japan (2019.11.17-2019.11.20)] 2019 24th Microoptics Conference (MOC) - Study of Plasmonic Nanolasers with Graphenea??Metal Interaction
摘要： We report the design, fabrication, and proof-of-concept characterization of an X-ray generator for improved X-ray absorption imaging that uses a nanostructured field emission cathode as the electron source and a microstructured transmission anode as the X-ray generating structure. Field emission cathodes consume less power, respond faster, and tolerate lower vacuum than the thermionic cathodes used in conventional X-ray generators. The use of a transmission anode, instead of a conventional reflection anode, allows filtering of the background radiation (bremsstrahlung) while allowing efficient generation of X-ray at lower voltages by exciting atomic shell transitions, resulting in emission of X-ray with narrow spectral linewidth for sharper imaging of biological tissue. The fabricated field emission cathode contains arrays of self-aligned and gated silicon field emitters. The field emission cathodes turn on at bias voltages as low as 25 V, and their gates transmit almost 100% of the electrons to the anode. The cathodes produce per-emitter electron currents in excess of 2 μA (current density >2 A/cm2) at a bias voltage of 80 V. A desktop rig is built to generate X-ray with a field emission cathode and transmission anode. Using the facility, we obtained X-ray absorption images of several objects. The images clearly show details under 500 μm in size, as well as soft tissue and fine bone structures without using contrast agents.
关键词： medical imaging,Field emission,X-ray generation
更新于2025-09-19 17:13:59
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Novel Confocal-Laser-Scanning-Microscopy and conventional measures investigating eroded dentine following dentifrice dab-on and brushing abrasion
摘要： Objectives: To validate novel non-contacting Confocal-Laser-Scanning-Microscopy (CLSM) methodology with conventional Contacting Pro?lometry (CP) measures investigating brushing or dab-on of stannous-?uoride dentifrice on early aggressive dentine erosion. Methods: 75 polished human dentine samples were prepared and eroded in agitated 6% citric acid then randomly allocated into 5 intervention groups; arti?cial saliva control (1); controlled use of a pressure sensitive counter-rotating oscillatory powered toothbrush with sodium-?uoride NaF (2) or stannous-?uoride SnF2 (3), and dab-on application of NaF (4) or SnF2 (5). Samples underwent three cycles of intervention and 2-min agitated 6 % citric acid challenges. CLSM images were taken and 3D reconstructions produced of step height using a developed software algorithm. In addition, 20 % samples were randomised and pro?led using CP to measure step height and surface roughness. Vickers's diamond micro-hardness testing was carried out on all samples. Results: Comparing CLSM and CP; Pearson correlation was 0.77 and Intra-class correlation 0.81 (p ? 0.01). There were no signi?cant statistical differences in step height between groups using both CLSM and CP. From baseline, SnF2 brushing (3) increased micro-hardness more than control (1) (p ? 0.03), NaF (4) and SnF2 dab-on (5) (p (cid:2) 0.001), and increased surface roughness more than control (p ? 0.02), NaF brushing (2) and NaF dab-on (4) (p (cid:2) 0.017). Dab-on of SnF2 (5) produced rougher surfaces than control (1) (p ? 0.014) and reduced hardness compared with NaF brushing (p ? 0.04). Conclusions: Good agreement and correlation exists between CLSM and CP measures in dentine. There were no signi?cant differences in surface loss after interventions between groups. Compared with control, SnF2 application increased dentine surface roughness and SnF2 controlled powered brushing application increased dentine hardness, likely caused by exposure of uneroded dentine. Clinical signi?cance: Isosurfaces produced using CLSM can be used to represent dentine step height loss. They show good correlation and agreement with conventional CP measures, following early aggressive erosion-abrasion cycles of dentine. The CLSM and computer algorithm therefore provides an accurate, standalone and non-contacting three-dimensional measurement of early dentine wear. Stannous-?uoride brushing, and dab-on application offer no bene?ts following early aggressive erosion in dentine. To reduce dentine wear, limiting erosive challenges and avoiding brushing post-erosion is advised.
关键词： Prosthetic dentistry,Medical imaging,Dab-on,Mathematical biosciences,Dental materials,Biophysics,Dentistry,Erosion,Measurement,Software engineering,Applied computing in medical science,Abrasion,Dentifrice,Biocomputational method,Dentine-wear
更新于2025-09-16 10:30:52
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Evaluation of radiographers’ knowledge and attitudes of image quality optimisation in paediatric digital radiography in Saudi Arabia and Australia: a survey‐based study
摘要： Introduction: Digital radiography (DR) systems enable radiographers to reduce the radiation dose to patients while maintaining optimised image quality. However, concerns still exist about paediatric patients who may be exposed to an increased level of radiation dose which is not needed for clinical practice. The purpose of this study was to evaluate the knowledge, awareness and attitudes, in terms of image quality optimisation of radiographers undertaking paediatric DR in Australia and Saudi Arabia. Methods: A survey-based study was devised and distributed to radiographers from Australia and Saudi Arabia. Questions focused on Australian and Saudi Arabian radiographers’ knowledge and attitude of paediatric DR examinations. Results: There were 376 participants who responded to the survey from both countries. A major finding showed that most participants lack knowledge in the area of paediatric DR examinations. Most participants from Australia had received no formal training in paediatric digital radiography (79%), whereas nearly half of the participants from Saudi Arabia received no training (45%). Approximately three out of four radiographers from both countries believed that when using DR they did not need to change the way they collimate the beam as DR images can be cropped using post-processing methods. Conclusion: The finding of this study demonstrates that radiographers from both countries should improve their understanding and clinical use of DR in paediatric imaging. More education and training for both students and clinicians is needed to enhance radiographer performance in digital radiography and improve their clinical practices.
关键词： radiographers’ knowledge,Medical imaging,peadiatric radiography,quaility assessment
更新于2025-09-16 10:30:52
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Graphene-like Si <sub/>3</sub> N <sub/>3</sub> and Si <sub/>3</sub> N <sub/>4</sub> Nanolayers on Silicon Surface
摘要： In this paper, we present a 1050-nm electrically pumped microelectromechanically tunable vertical cavity surface-emitting laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept-source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost and complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide-field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over 6 mm × 6 mm and 3 mm × 3 mm fields to show retinal vasculature and capillary structure near the fovea. These results demonstrate the feasibility of electrically pumped MEMS-VCSELs in ophthalmic instrumentation, the largest clinical application of OCT. In addition, we estimate that the 3 dB coherence length in air is 225 ± 51 m, far greater than required for ophthalmic SS-OCT and suggestive of other distance ranging applications.
关键词： Medical imaging,tunable lasers,optical coherence tomography,micro and nano opto-electromechanical systems (MOEMS),semiconductor lasers
更新于2025-09-16 10:30:52
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Effect of Affinity Discontinuity on Heterojunction p-i-n Solar Cell Performance
摘要： We report the design, fabrication, and proof-of-concept characterization of an X-ray generator for improved X-ray absorption imaging that uses a nanostructured field emission cathode as the electron source and a microstructured transmission anode as the X-ray generating structure. Field emission cathodes consume less power, respond faster, and tolerate lower vacuum than the thermionic cathodes used in conventional X-ray generators. The use of a transmission anode, instead of a conventional reflection anode, allows filtering of the background radiation (bremsstrahlung) while allowing efficient generation of X-ray at lower voltages by exciting atomic shell transitions, resulting in emission of X-ray with narrow spectral linewidth for sharper imaging of biological tissue. The fabricated field emission cathode contains arrays of self-aligned and gated silicon field emitters. The field emission cathodes turn on at bias voltages as low as 25 V, and their gates transmit almost 100% of the electrons to the anode. The cathodes produce per-emitter electron currents in excess of 2 μA (current density >2 A/cm2) at a bias voltage of 80 V. A desktop rig is built to generate X-ray with a field emission cathode and transmission anode. Using the facility, we obtained X-ray absorption images of several objects. The images clearly show details under 500 μm in size, as well as soft tissue and fine bone structures without using contrast agents.
关键词： medical imaging,Field emission,X-ray generation
更新于2025-09-16 10:30:52
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Medical Imaging Informatics: Towards a Personalized Computational Patient
摘要： Medical Imaging Informatics has become a fast evolving discipline at the crossing of Informatics, Computational Sciences, and Medicine that is profoundly changing medical practices, for the patients’ benefit.
关键词： personalized computational patient,Medical Imaging Informatics,computational medicine,computational anatomy
更新于2025-09-11 14:15:04