Camera-based Imaging System Research Articles

Sub-micrometer real-time imaging of trajectory of alpha particles using GAGG plate and CMOS camera

High-resolution and real-time imaging of the trajectories of alpha particles is desired in nuclear medicine and nuclear engineering. Although an imaging method using a scintillator plate combined with a magnifying unit and a cooled electron multiplying charge-coupled device (EM-CCD) camera is a possible method of obtaining high-resolution trajectory images, the spatial resolution of the system is limited to ∼2 μm. To overcome the spatial resolution limitations of this method on trajectory imaging, we used a cooled complementally metal oxide (CMOS) camera in which the sensor had a much larger number of pixels, which were also smaller. Using the CMOS camera based imaging system, we could measure the trajectories of alpha particles in real time with the spatial resolution of 0.34 μm FWHM. With smoothing of the images to reduce image noise, spatial resolution was still kept to less than 0.75 μm. We conclude that this CMOS camera-based alpha-particle trajectory-imaging system is promising for alpha-particle or other particles imaging where ultrahigh spatial resolution is required.

Angle-Dependent Transport Theory-Based Ray Transfer Function for Non-Contact Diffuse Optical Tomographic Imaging

This work presents a generalized angle-dependent ray transfer function that can accurately map the angular and spatial distribution of light intensities on the tissue surface onto a camera image plane in a non-contact camera-based imaging system. The method developed here goes beyond existing ray transfer models that apply to angle-averaged tomographic data alone. The angle-dependent ray transfer operator was constructed using backward ray tracing based on radiation surface theory. The proposed method was validated using numerical phantoms and experimental data from an actual non-contact imaging system.

Novel 3D Imaging Systems for High-Throughput Phenotyping of Plants

The use of 3D plant models for high-throughput phenotyping is increasingly becoming a preferred method for many plant science researchers. Numerous camera-based imaging systems and reconstruction algorithms have been developed for the 3D reconstruction of plants. However, it is still challenging to build an imaging system with high-quality results at a low cost. Useful comparative information for existing imaging systems and their improvements is also limited, making it challenging for researchers to make data-based selections. The objective of this study is to explore the possible solutions to address these issues. We introduce two novel systems for plants of various sizes, as well as a pipeline to generate high-quality 3D point clouds and meshes. The higher accuracy and efficiency of the proposed systems make it a potentially valuable tool for enhancing high-throughput phenotyping by integrating 3D traits for increased resolution and measuring traits that are not amenable to 2D imaging approaches. The study shows that the phenotype traits derived from the 3D models are highly correlated with manually measured phenotypic traits (R2 > 0.91). Moreover, we present a systematic analysis of different settings of the imaging systems and a comparison with the traditional system, which provide recommendations for plant scientists to improve the accuracy of 3D construction. In summary, our proposed imaging systems are suggested for 3D reconstruction of plants. Moreover, the analysis results of the different settings in this paper can be used for designing new customized imaging systems and improving their accuracy.

PHSOR06 Presentation Time: 10:25 AM: A Novel Gamma Camera-Based System for Real-Time Visualization of 192Ir Source Position in High Dose Rate Brachytherapy

Purpose: The physical location of the 192Ir source in high-dose-rate (HDR) brachytherapy is currently invisible to the treatment team during treatment delivery. Although the in-room radiation monitor(s) can indicate whether the source is inside or outside the afterloader, the inability to easily visualize the physical source location makes it difficult in responding to radiation safety events and in treatment delivery verification. The purpose of this work was to develop a gamma camera-based imaging system for real-time visualization of the 192Ir source position during the HDR treatment delivery.

Precise Estimation of NDVI with a Simple NIR Sensitive RGB Camera and Machine Learning Methods for Corn Plants.

The normalized difference vegetation index (NDVI) is widely used in remote sensing to monitor plant growth and chlorophyll levels. Usually, a multispectral camera (MSC) or hyperspectral camera (HSC) is required to obtain the near-infrared (NIR) and red bands for calculating NDVI. However, these cameras are expensive, heavy, difficult to geo-reference, and require professional training in imaging and data processing. On the other hand, the RGBN camera (NIR sensitive RGB camera, simply modified from standard RGB cameras by removing the NIR rejection filter) have also been explored to measure NDVI, but the results did not exactly match the NDVI from the MSC or HSC solutions. This study demonstrates an improved NDVI estimation method with an RGBN camera-based imaging system (Ncam) and machine learning algorithms. The Ncam consisted of an RGBN camera, a filter, and a microcontroller with a total cost of only $70 ~ 85. This new NDVI estimation solution was compared with a high-end hyperspectral camera in an experiment with corn plants under different nitrogen and water treatments. The results showed that the Ncam with two-band-pass filter achieved high performance (R2 = 0.96, RMSE = 0.0079) at estimating NDVI with the machine learning model. Additional tests showed that besides NDVI, this low-cost Ncam was also capable of predicting corn plant nitrogen contents precisely. Thus, Ncam is a potential option for MSC and HSC in plant phenotyping projects.

2D Kinematic Quantification of Soil Particles around Growing Plant Root based on Optical Mechanics

The quantitative kinematic description of the surrounding soil particles during root growth is a technical challenge and biologically important. In this study, a two-dimensional camera-based imaging system was used to observe micro scale interactions between plant roots and soil particles. Maize root tip was imaged during ingress into the soils. This produced a series of two-dimensional images that represent temporal resolution of the geometric soil and root configurations at the micrometer scale. These images were used as inputs for full-field kinematic quantification methods, which enabled the analysis of two-dimensional deformation of the soils around elongating root. Correlation-based discrete object tracking and contour updating were used to track the shapes and the locations of soil particles and soil aggregates, while incremental digital image correlation was proposed to extract deformation and strain field within soil particle and soil aggregate. These techniques allowed the full-field displacements and strains of the soil to be quantified and the changes in shapes of soil particles to be visualized. Experimental results show that the presented shape tracking scheme, incremental digital image correlation and the research findings will be useful for the measurement and quantification of soil particle kinematics of soil-root physical interactions.

WITHDRAWN: Practical methods for characterizing the optical performance of digital camera-based imaging systems: image processing application using ImageJ

Abstract In this paper, practical and simple methods for characterizing the optical performance of a digital CCD camera equipped with a zoom lens using test targets projected by a Newtonian collimator coupled to an integrating sphere and a halogen light source are presented. The presented methods include the evaluation of the CCD camera system modulation transfer function (MTF), uniformity, dynamic range, linearity and signal-to-noise ratio (S/N) properties in the visible region of the spectrum. Through out this work image processing for the recorded target images is performed using ImageJ. In addition, the paper presents a comparison between MTF measurements collected with a 1951-USAF resolution test target and a slanted edge test target. Finally, simple mathematical expressions for the measured optical system performance properties are provided. The presented optical system characterization methods can provide researchers with the needed data when a CCD or CMOS digital camera is integrated with a lens system.

Practical Methods for Characterizing the Optical Performance of Digital Camera-Based Imaging Systems

In this paper, practical and simple methods for characterizing the optical performance of a digital CCD camera equipped with a zoom lens using test targets projected by a Newtonian collimator coupled to an integrating sphere and a halogen light source are presented. The presented methods include the evaluation of the CCD camera system modulation transfer function (MTF), uniformity, dynamic range, linearity, and signal-to-noise ratio (S/N) properties in the visible region of the spectrum. Through out this work image processing for the recorded target images is performed using ImageJ. In addition, the paper presents a comparison between MTF measurements collected with a 1951-USAF resolution test target and a slanted edge test target. Finally, simple mathematical expressions for the measured optical system performance properties are provided. The presented optical system characterization methods can provide researchers with the needed data when a CCD or CMOS digital camera is integrated with a lens system.

Preliminary Experimentation of Fast Neutron Radiography with D-T Neutron Generator at BARC

An experimental study on fast neutron radiography (FNR) has been carried out using a laboratory based D-T neutron generator facility at Bhabha Atomic Research Centre (BARC) and initial results are presented. The aim was to develop an FNR system with a moderate intensity neutron source for imaging of specimen containing mixed low-Z and high-Z materials. The experimental set-up consists of a D-T neutron generator, collimator and an EMCCD camera based imaging system. Experiments were carried out with the neutron generator having a source strength of about 2 × 109 n/s and source spot size of 20 mm. To obtain optimum image quality with such a moderate neutron yield, a collimator has been designed having an inlet aperture of 10 mm and an L/D of 43. The imaging system was kept at an optimum distance from the collimator and various test samples of materials ranging from low Z to high Z were imaged. Thick samples in step wedge form, hole features in step wedge of polyethylene, mild steel and lead were imaged and analysed. Also a test sample of a low Z material (HDPE) with a hole placed behind a thick Pb was imaged to study the effect of thickness of high Z material on image quality with fast neutrons. The initial results emphasizes that a moderate yield D-T neutron generator based fast neutron radiography system with EMCCD camera could be deployed for field applications yielding moderate image quality to obtain first hand information of the investigated samples.

An upgraded camera-based imaging system for mapping venous blood oxygenation in human skin tissue

A camera-based imaging system was previously developed for mapping venous blood oxygenation in human skin. However, several limitations were realized in later applications, which could lead to either significant bias in the estimated oxygen saturation value or poor spatial resolution in the map of the oxygen saturation. To overcome these issues, an upgraded system was developed using improved modeling and image processing algorithms. In the modeling, Monte Carlo (MC) simulation was used to verify the effectiveness of the ratio-to-ratio method for semi-infinite and two-layer skin models, and then the relationship between the venous oxygen saturation and the ratio-to-ratio was determined. The improved image processing algorithms included surface curvature correction and motion compensation. The curvature correction is necessary when the imaged skin surface is uneven. The motion compensation is critical for the imaging system because surface motion is inevitable when the venous volume alteration is induced by cuff inflation. In addition to the modeling and image processing algorithms in the upgraded system, a ring light guide was used to achieve perpendicular and uniform incidence of light. Cross-polarization detection was also adopted to suppress surface specular reflection. The upgraded system was applied to mapping of venous oxygen saturation in the palm, opisthenar and forearm of human subjects. The spatial resolution of the oxygenation map achieved is much better than that of the original system. In addition, the mean values of the venous oxygen saturation for the three locations were verified with a commercial near-infrared spectroscopy system and were consistent with previously published data.

SU-E-T-51: Characterization of a Novel CCD Camera Based Imaging System for Radiochromic Film Dosimetry

Purpose: In this paper we present work to further develop and characterize a novel method of reading radiochromic film. The technique is benchmarked against imaging on a clinically used Epson 10000XL scanner, using well characterized standard dose deliveries and patient IMRT QA results. Methods: A purpose‐built CCD camera‐based film digitizer was designed and prototyped with Modus Medical (London, Ontario). The system consists of a camera mounted above a LED lightbox, interfaced with computer image acquisition software. The system was based on components of the Vista optical CT scanner (Modus Medical Devices Inc.) and looks to improve on the flat‐bed scanner based dosimetry system, which suffer from film orientation dependence and non‐uniform scanner sensitivity. Various characteristics imaging system performance were measured including: dependence on camera aperture size, spatial resolution, light scatter contamination, lightbox temperature variation effects, and signal‐to‐noise ratio (SNR). Dose readout accuracy has also been determined using films that have been imaged using white‐light and colour lightbox illumination system. Results are compared with readout using the Epson scanner. Results: The new system provides fast, orientation independent readout of radiochromic film. High resolution (0.25 mm x 0.25 mm pixel size) and high signal‐to‐noise ratio (SNR = 280 for 230 cGy, 10x10 cm square field) images are obtained in 6.7 seconds, averaging 100 frames. A warm‐up time of at least one hour stabilizes light output and eliminates temperature effects. The readout of all test films agree well (to within 1% dose difference over most of the film) to the dose determined by other approaches. Conclusion: This new imaging technique shows good promise to simplify and improve on existing film dosimetry readout. Further development towards a commercial system is currently underway with Modus Medical. Research funding support provided by the Canadian Institutes of Health Research (CIHR)

Robust Method for Automated Segmentation of Frames with/without Distress from Road Surface Video Clips

Automated processing of road surface video clips captured for road condition assessment is necessary to detect the existence of road surface distress in less time and efforts. This paper presents a robust method for automated segmentation of frames with/without distress from road surface video clips captured by existing camera based imaging systems without any artificial lighting systems. The proposed method is based on an adaptive thresholding technique and user defined decision logic for automated detection of road surface distresses out of such video clips. This method has been implemented in a Windows Vista environment with the help of Visual Studio 2008 and OpenCV library and tested on 31 road surface video clips of Indian Highways. The results show that this method can segment a road surface video clip automatically into two categories of video frames, namely frames with distress and frames without distress, with accuracy up to 96% while saving a considerable amount of time and manpower resources.

Numerical simulation of non-convex heat transfer of the weld pool surface during laser welding of titanium alloy

The coupled heat transfer and fluid flow behaviours during deep penetration laser welding of titanium alloy sheet were investigated with a coupled three-dimensional transient keyhole welding model and a high speed in situ CCD camera-based imaging system. An unusual small scale heat transfer phenomenon of the weld pool that the shape of some high temperature isothermal lines in the central part of top weld pool surface could be regularly concave towards to welding direction, was found by the theoretical modelling and high speed imaging experiments. It was shown that the occurrence of this phenomenon closely relates to the vigorously convective heat transfer of the weld pool.

An integrated instrument for rapidly deforming living cells using rapid pressure pulses and simultaneously monitoring applied strain in near real time

Because many types of living cells are sensitive to applied strain, different in vitro models have been designed to elucidate the cellular and subcellular processes that respond to mechanical deformation at both the cell and tissue level. Our focus was to improve upon an already established strain system to make it capable of independently monitoring the deflection and applied pressure delivered to specific wells of a commercially available, deformable multiwell culture plate. To accomplish this, we devised a custom frame that was capable of mounting deformable 6 or 24 well plates, a pressurization system that could load wells within the plates, and a camera-based imaging system which was capable of capturing strain responses at a sufficiently high frame rate. The system used a user defined program constructed in Labview(®) to trigger plate pressurization while simultaneously allowing the deflection of the silicone elastomeric plate bottoms to be imaged in near real time. With this system, up to six wells could be pulsed simultaneously using compressed air or nitrogen. Digital image capture allowed near-real time monitoring of applied strain, strain rate, and the cell loading profiles. Although our ultimate goal is to determine how different strain rates applied to neurons modulates their intrinsic biochemical cascades, the same platform technology could be readily applied to other systems. Combining commercially available, deformable multiwell plates with a simple instrument having the monitoring capabilities described here should permit near real time calculations of stretch-induced membrane strain in multiple wells in real time for a wide variety of applications, including high throughput drug screening.

Quantitative imaging cytometry: instrumentation of choice for automated cellular and tissue analysis

Laser scanning cytometry (LSC) is the technology of choice for automated, quantitative high-content, high-throughput analysis of heterogeneous cellular samples and tissue specimens. LSC complements flow cytometry, allowing analysis of samples attached to solid substrates, such as adherent cells and tissue specimens. It also augments confocal imaging systems, making it far easier to perform population and subpopulation analysis and gather quantitative data on thousands of cells. LSC offers many advantages compared with camera-based imaging systems. Covering a broad range of applications, LSC technology is 'must have' instrumentation in every core flow cytometry and imaging facility and in all laboratories that study adherent cells and tissues.

Automated coregistered imaging using a hand-held probe-based optical imager

Near-infrared optical imaging holds a promise as a noninvasive technology toward cancer diagnostics and other tissue imaging applications. In recent years, hand-held based imagers are of great interest toward the clinical translation of the technology. However hand-held imagers developed to date are typically designed to obtain surface images and not tomography information due to lack of coregistration facilities. Herein, a recently developed hand-held probe-based optical imager in our Optical Imaging Laboratory has been implemented with novel coregistration facilities toward real-time and tomographic imaging of tissue phantoms. Continuous-wave fluorescence-enhanced optical imaging studies were performed using an intensified charge coupled device camera based imaging system in order to demonstrate the feasibility of automated coregistered imaging of flat phantom surfaces, using a flexible probe that can also contour to curvatures. Three-dimensional fluorescence tomographic reconstructions were also demonstrated using coregistered frequency-domain measurements obtained using the hand-held based optical imager. It was also observed from preliminary studies on cubical phantoms that multiple coregistered scans differentiated deeper targets (approximately 3 cm) from artifacts that were not feasible from a single coregistered scan, demonstrating the possibility of improved target depth detectability in the future.

Influence of the Number of Samples of the Training Set on Accuracy of Color Measurement and Spectral Reconstruction

In this article the authors analyze the influence of the number of samples in a training set on the accuracy of color and spectral measurements made using a colorimetric and multispectral imaging system. The authors develop a method for establishing the minimum and/or sufficient number of color samples in the training set above which the system's performance is independent of the number of samples. The authors also consider the dependence of the system's performance on the training set itself. Two setups of a charge coupled device camera-based imaging system are used for this purpose: a colorimetric configuration with three acquisition channels and a multispectral configuration with seven acquisition channels. On the basis of the criterion established in this article, the results show that the system's performance in terms of the accuracy of color measurement and spectral reconstruction seems to be independent of the training set used when over 110 samples are used for the colorimetric configuration and over 120 samples for the multispectral configuration. This result is true for both the number of samples in the training set and the training set itself. The method that the authors developed can be generalized and implemented in the industry for any application in which an imaging capture device is used for color and spectral measurements.

Near-Infrared Imaging of SOFCs with Methane and Propane Fuels

A Si-CCD camera-based imaging system is used in-situ to study the effects of hydrocarbon fuels on Ni/YSZ solid oxide fuel cell anode temperatures. Methane and propane are used as fuels. Temperature variations are investigated to explore how carbon deposition varies with fuel, and how deposition and electrochemical oxidation of carbon affect the anode. The temperature change that results from carbon growth during CH4 flow is -2.3 ºC. The temperature change due to the oxidation of carbon deposits from CH4 is +2.0 ºC. Similar experiments with C3H8 produced temperature shifts of -3.4 ºC and +2.4 ºC during fuel flow and electrochemical oxidation, respectively. The temperature drops more quickly when C3H8 is used instead of CH4. As deposits are electrochemically oxidized, the maximum temperature occurs ~2 minutes earlier in the CH4 case. The time profiles indicate that more carbon is present in C3H8 cells.

A composite (stacked) picture generation technique for spectral profile representation of dye laser

In this paper, a new technique for data representation format from video recording of spectral profile of tunable dye laser has been formulated. Only a part of the acquired images acquired sequentially in programmed time interval, was used to make the composite picture to measure variation of the parameters. A CCD camera based imaging system was used to confine the spectral pattern. No additional hardware other than image capturing device was used. The technique developed reduces the storage space required in the computer and also enhances the measurement speed significantly. The software algorithm developed has been used effectively to measure various parameters of tunable dye lasers and other optical sources.

Substrate Requirements for SPPL2b-dependent Regulated Intramembrane Proteolysis

Intramembrane proteolysis is now widely recognized as an important physiological pathway required for reverse signaling and membrane protein degradation. Aspartyl intramembrane cleaving proteases of the GXGD-type play an important regulatory role in health and disease. Besides gamma-secretase/presenilin, signal peptide peptidase (SPP) and SPP-like (SPPL) peptidases also belong to the family of GXGD-type aspartyl proteases. Although recently the first SPPL2a/b substrates have been identified, very little is known about substrate requirements, which allow them to be efficiently processed within the membrane. We demonstrate that similar to gamma-secretase substrates, intramembrane proteolysis of Bri2 (Itm2b) is greatly facilitated by an initial shedding event mediated by ADAM-10. Serial deletions revealed that the length of the ectodomain negatively correlates with efficient intramembrane proteolysis. Bri3 (Itm2c), which is highly homologous to Bri2, fails to be shed. Failure of shedding of Bri3 is accompanied by a lack of intramembrane proteolysis by SPPL2b. Surprisingly, a low molecular weight membrane-retained stub of Bri3 also fails to be processed by SPPL2b, indicating that shedding per se is not sufficient for subsequent intramembrane proteolysis. Extensive domain swapping analysis reveals that primary sequence determinants within the intracellular domain and the transmembrane domain together with short luminal juxtamembrane sequences are required for efficient intramembrane proteolysis.