Search

PURPOSE: There is a growing interest in targeting minimally invasive surgery devices to the aqueous outflow system to optimize treatment outcomes. However, methods to visualize functioning, large-caliber aqueous and episcleral veins in-vivo are lacking. This pilot study establishes an ex-vivo system to evaluate the use of a confocal laser microendoscope to noninvasively image episcleral vessels and quantify regional flow variation along the limbal circumference. METHODS: A fiber-optic confocal laser endomicroscopy (CLE) system with lateral and axial resolution of 3.5 μ m and 15 μ m, respectively, was used on three porcine and four human eyes. Diluted fluorescein (0.04%) was injected into eyes kept under constant infusion. The microprobe was applied to the sclera 1 mm behind the limbus to acquire real-time video. Image acquisition was performed at 15-degree intervals along the limbal circumference to quantify regional flow variation in human eyes. RESULTS: Vascular structures were visualized in whole human eyes without processing. Schlemms canal was visualized only after a scleral flap was created. Fluorescent signal intensity and vessel diameter variation were observed along the limbal circumference, with the inferior quadrant having a statistically higher fluorescein signal compared to the other quadrants in human eyes ( P < 0.05). CONCLUSION: This study demonstrates for the first time that the fiber-optic CLE platform can visualize the episcleral vasculature with high resolution ex-vivo with minimal tissue manipulation. Intravascular signal intensities and vessel diameters were acquired in real-time; such information can help select target areas for minimally invasive glaucoma surgery (MIGS) to achieve greater intraocular pressure reduction.

Underwater imaging is a challenging task because of the effects of scattering and absorption in water. Ghost imaging (GI) has attracted increasing attention because of its simple structure, long range, and achievability under weak light intensity. In an underwater environment, conventional imaging is limited by low sensitivity, resulting in fuzzy images, while ghost imaging can solve this problem. This study proposes underwater laser ghost imaging based on Walsh speckle patterns. According to the simulated and experimental results, noise resistance and a low sampling rate of ghost imaging based on Walsh speckle patterns are proved. As the turbidity of the underwater environment increases, the imaging quality of ghost imaging based on Walsh speckle patterns decreases. However, it remains much better than that of ghost imaging based on random speckle patterns and Hadamard speckle patterns, whereas conventional imaging is no longer distinguishable. Ghost imaging based on Walsh speckle patterns can be performed with a sampling rate lower than 10%, and the peak signal-to-noise ratio and the structural similarity of the results increase by 150.15% and 396.66%, respectively, compared with random speckle pattern ghost imaging. An identifiable image of ghost imaging based on Walsh speckle patterns can be reconstructed with a sampling rate of 6% in a turbid water environment, which is simulated with the concentration of the milk powder not higher than 11.0 g/L. This method promotes the further development of optical imaging technology for underwater targets with a low sampling rate based on ghost imaging.

Particle size measurement technology is widely used in many fields such as energy, materials, medicine, chemical industry, metallurgy, electronics, machinery, light industry, construction, etc., and has a very important meaning for improving product quality, increasing production efficiency, reducing energy consumption, realizing precision medicine, monitoring environmental pollution, etc. The particle size measurement method based on the optical principle has the advantages of fast response speed, and the particle size measurement range can reach nanometer level. However, there are still some problems in practical applications and need to be continuously improved. Three types of particle size measurement methods based on optical principles: Microscopy, light scattering, and laser imaging were summarized in this paper, including the measurement principles, measurement ranges, advantages and disadvantages, and application areas of various methods. On this basis, the prospects for the research of particle size measurement were prospected [ABSTRACT FROM AUTHOR]

• A laser differential imaging measurement model for immersed tunnel alignment is proposed. • The calibration model is given,and the measurement system is designed. • An underwater laser spot center extraction method is proposed. • Precision and repeatability assessment experiments are carried out, and are far better than the requirements. The precision of underwater alignment for tunnel elements directly impacts the closure state of immersed tunnels. The current global navigation satellite system measurement tower method provides centimeter-level precision; however, this is insufficient due to the tower deformation at great water depths, which fails to meet alignment requirements. In this study, a novel immersed tunnel alignment measurement method using laser differential imaging is developed. A unique sensor layout is designed to measure the axial angle and distance between tunnel elements. The system design is implemented, and its laser data processing scheme is optimized to improve performance base on this sensor layout. The experimental results demonstrate that the accuracy of underwater laser spot extraction is better than 1.16 pixels, and the precision of axial angle and axial distance alignment measurements is better than 25″ and 1.6 mm, with repeatability precision exceeding 10.55″ and 0.53 mm. The laser-based alignment measurement method is not affected by the depth of water, satisfying the required precision of immersed tunnel alignment. These results can be applied to future immersed tunnel installations without measuring towers, providing a novel method for achieving automated and unmanned intelligent construction of immersed tunnels. [ABSTRACT FROM AUTHOR]

Herein, a large reduction in the speckle noise is observed using a thin electroresponsive film consisting of a chiral nematic liquid crystal (LC) that has been enhanced with the addition of a redox dopant. Two different redox dopants are investigated over a range of concentrations, one being an electron acceptor and the other being an electron donor redox dopant. Results are presented that show that the incorporation of either of these dopants leads to a greater reduction in the speckle contrast than that observed using just the chiral nematic LC host when subjected to electrohydrodynamic instabilities. Furthermore, it is found that the permanent electrochemical reactions typically observed when ionic dopants, such as cetyltrimethylammonium bromide, are used are not observed for these devices, resulting in a considerable improvement in terms of the operating lifetime of the speckle reducer technology. To conclude, results that show that the speckle contrast can be reduced to C = 0.11 ± 0.02 at a temperature of 30 ºC are presented and the improvement of the quality of an image generated using a modified commercial projector fitted with a monochromatic laser source is demonstrated.

In this paper, we present a more efficient strategy than existing solutions to enhance the lateral resolution of low photon 3D-LiDAR operating in Geiger mode. Our pipeline makes it possible to reconstruct 3D-images with an unprecedented lateral-resolution, simultaneously at low photon count and Hertz level framerates. It is applied on simulated GmAPD 3D-LiDAR signals. Signals acquired using these kind of sensors are unsuitable for direct applications of Compressive Sensing algorithms. Our contribution focuses on a more efficient strategy for waveform denoising and reconstruction. For each pixel, we reconstruct sub-pixels with a Compressive Sensing approach. After describing our method, we demonstrate its applicability on realistic simulated data. • Proposed methodology increases the lateral resolution of SWIR-optimized GmAPD. • New statistical method defined to denoise data from active imaging systems. • Method is suitable for embedded systems and on board post-processing. [ABSTRACT FROM AUTHOR]

Purpose: There is a growing interest in targeting minimally invasive surgery devices to the aqueous outflow system to optimize treatment outcomes. However, methods to visualize functioning, large-caliber aqueous and episcleral veins in-vivo are lacking. This pilot study establishes an ex-vivo system to evaluate the use of a confocal laser microendoscope to noninvasively image episcleral vessels and quantify regional flow variation along the limbal circumference. Methods: A fiber-optic confocal laser endomicroscopy (CLE) system with lateral and axial resolution of 3.5 μ m and 15 μ m, respectively, was used on three porcine and four human eyes. Diluted fluorescein (0.04%) was injected into eyes kept under constant infusion. The microprobe was applied to the sclera 1 mm behind the limbus to acquire real-time video. Image acquisition was performed at 15-degree intervals along the limbal circumference to quantify regional flow variation in human eyes. Results: Vascular structures were visualized in whole human eyes without processing. Schlemm's canal was visualized only after a scleral flap was created. Fluorescent signal intensity and vessel diameter variation were observed along the limbal circumference, with the inferior quadrant having a statistically higher fluorescein signal compared to the other quadrants in human eyes ( P < 0.05). Conclusion: This study demonstrates for the first time that the fiber-optic CLE platform can visualize the episcleral vasculature with high resolution ex-vivo with minimal tissue manipulation. Intravascular signal intensities and vessel diameters were acquired in real-time; such information can help select target areas for minimally invasive glaucoma surgery (MIGS) to achieve greater intraocular pressure reduction.

Introduction The texture of fresh fruit is determined by the structural and mechanical properties of tissue. It depends on climate, maturity, variety and postharvest condition. During ripening, due to loss of turgor, degradation of starch and cell walls, the flesh of apple softens. The relationship between fruit quality and its physiological changes has been widely investigated. Using techniques according to the principles of force-deformation, impact, and vibration tests, texture of fruit and its mechanical properties can be associated, conventionally. In analyzing the vitality of biomaterials; a non-invasive technique based on the optical phenomenon is the Biospeckle method which occurs when the surface of the sample is illuminated by laser light. It seems that because of the fact that the laser light can penetrate tissue, it is possible to obtain information about the texture and cell condition from tissue under the skin. This means that, there would be a chance to detect and monitor the variation of cells and try to make a model to predict mechanical properties. Therefore, the overall objective of this study was to develop prediction models based on biospeckle imaging to predict mechanical properties of ripe Golden Delicious apples. Materials and Methods The 400 fresh and intact 'Golden Delicious' apples were harvested and were prepared for mechanical tests and biospeckle imaging. Biospeckle imaging was carried out first, followed by compression and creep test and then penetration test. During imaging, to avoid environmental reflections, the process was carried out in a dark and closed chamber. Biospeckle activity was saved as a video (AVI format) in a computer for analyzing. The THSP method was used to analyze biospeckle activity in samples. The indices which have been used for analyzing biospeckle images are divided into 3 statistical features and 4 textural features. Apples were cut in half. One of the halves was used for cylindrical sample extraction for uniaxial compression and creep tests and another was used for penetration test. From compression tests the tangent modulus of elasticity, stress and strain of bio-yield and failure energy for toughness calculation were determined. The creep behavior was obtained by fitting the Burger's model to the experimental data. In penetration test, a stainless steel probe with a hemispherical tip was used for peeled and unpeeled samples. For each sample maximum penetration force and energy were obtained. Prediction of mechanical property was carried out using adaptive neuro-fuzzy inference system (ANFIS). To reduce the dimension of the input vector the PCA was used. Four significant adjustments were made in the structure of ANFIS in order to find the best models. The models were evaluated using RMSECV, RMSEP, MBEC, MBEP, RC, and RP. Results and Discussion Models for modulus of elasticity prediction have Rp=0.821, 0778, 0.791, 0.880, and 0.843 for 4 compression rate and secant modulus, respectively. Clearly, the results from this research are encouraging, indicating the potential of using speckle imaging system for predicting apple fruit mechanical properties. Comparing to the all texture analysis techniques, Wavelet and GLRLM provided good results for most properties leading to select them as the best techniques for analysis of biospeckle images because of their consistency in prediction performance. Prediction model for break strain has the highest Rp (Rp=0.920) followed by the retarded time (Rp=0.890), retarded viscosity (Rp=0.886) and maximum penetration force in unpeeled case (Rp=0.883). A lower correlation (Rp = 0.728) was observed for initial viscosity. Conclusions The described optical method based on biospeckle represents an innovative and reliable method for rapid and non-invasive detection of mechanical properties. The results of the evaluation showed that, as time passes, fresh apples due to the loss of water in both the elasticity and the biospeckle activity were dropped. Biospeckle imaging can accurately predict mechanical properties. The average accuracy of best prediction of mechanical properties models was R2=0.899. The present results can provide the basis of future development of in-line quality monitoring during apple quality control.

The speckle usually degrades the signal quality for coherent detection or imaging. In this paper, under the single-image constraint, we propose a two-step weighted robust regression method for speckle removal, where the first step is to smooth the speckle-noisy image by means of block matching and 3D filtering (BM3D), and the second step is further to apply a weighted robust regression to discriminate between the signal and residual speckle and to recover the edge information. Theoretical demonstration is presented, and experimental results with laser illumination are shown and compared to other competing methods. The experiments show that our method has robustness and prominent improvement of 12 ∼ 19% in the speckle removal task. [ABSTRACT FROM AUTHOR]

Background/aim: Pancreatic cancer is a recalcitrant disease with 5-year survival of only 12%. Improved mouse models of pancreatic cancer are critical for discovery of effective therapeutics., Materials and Methods: Orthotopic mouse nude-mouse models of pancreatic cancer were established with the human pancreatic-cancer cell line Panc-1 expressing green fluorescent protein (GFP) by transplanting tumor fragments into the pancreas, using the procedure of surgical orthotopic implantation (SOI). Four weeks after establishment of the orthotopic models, the mice were imaged with the Analytik Jena UVP Biospectrum Advanced with a very-narrow-band-width excitation at 487 nm and peak emission at 513 nm., Results: Non-invasive fluorescence imaging of the mice implanted with Panc-1-GFP showed a very bright tumor in the area of the pancreas and peritoneal cavity. The skin background autofluorescence was absent. When a laparotomy was performed on the mouse for open imaging, the tumor on the pancreas was clearly imaged. There was very clear concordance of the non-invasive image and the image obtained during laparotomy., Conclusion: A precise orthotopic mouse model of pancreatic cancer was developed in which there was high concordance between non-invasive and invasive fluorescence imaging due to the ultra-bright signal and ultra-low background using very-narrow-band-width laser fluorescence excitation. This model can be used for high-throughput in vivo screening for improved therapeutics for pancreatic cancer., Competing Interests: AW, NC, ST and SG are employees of Analytik Jena. YA, YT, NM, KO, SM and RMH are non-salaried associates of AntiCancer Inc. AntiCancer Inc. uses mouse models of cancer for contract research., (Copyright 2024, International Institute of Anticancer Research.)

Spray drift, which may result in a waste of pesticides and environmental risks, has been viewed as a concern in the use of pesticides. The indoor test of spray drift is mainly measured by the wind tunnel which possess a more stable and controllable wind speed. Recently, the laser is widely used in a range of fields owing to its perfect light stability and the Tyndall phenomenon is remarkable in dispersed particles. Therefore, this paper develops a new method for measuring the drift of pesticide spray in wind tunnels. According to the international standard ISO22856, 11 kinds of additives such as silicone and vegetable oil were measured in the wind tunnel using LU120-01 nozzle from Lechler, Germany. Each additive adjuvant liquid was sprayed for 5 s, repeated 3 times. The collectors were Polytetrafluoroethylene (PTFE) lines and Polyvinyl Chloride (PVC) cards. The PTFE lines were placed at a distance of 2 m from the nozzle in the downwind direction and were 5-85 cm in height (interval 10 cm). The collected droplet particles were analyzed by LS-55 fluorescence analyzer. At the same time, laser imaging technology was used to continuously image during the spraying process. The exposure time is 1/8 s, the ISO is 100 and the aperture is f/1.8. The shutter was controlled by Bluetooth Controller. Combined with computer image rapid batch processing, RGB three-color layer was filtered by MATLAB 2017a, and R-layer minus G-layer image was calculated. The maximum value of gray level and the image feature parameters such as position, barycentric coordinates, and the average value in the horizontal and vertical directions of the image were extracted. The drift rate, feature height and drift potential index (DIX) of the spray drift were calculated from the actual measurement results. The calculated result was fitting with the measured result. The fitting results showed that the maximum value and position of maximum in the x and y axis, the center of gravity coordinates, and the mean value were significantly correlated (Sig. F<0.05) with the drift rate, drift feature height, and DIX. The correlation coefficient was greater than 0.91, the maximum absolute value relative error was only 5.9%. The fitting results of vertical feature height and horizontal feature distance were the best, the average relative error was 0, the absolute relative error was 0.6% and 1.5% (vertical and horizontal direction), followed by DIX index (the absolute relative error of the vertical and horizontal direction were 4.8% and 3.2%) and drift rate (the absolute relative error of the vertical and horizontal direction were 5.9% and 5.3%). It showed that this method could be used to evaluate the drift of droplets accurately. The test speed was faster than the traditional measurement method, and one picture only cost less 1 s for calculation. The test repeatability was high, the DIX index had a comprehensive accuracy of 96%. The test was no needed consumables, which greatly reduced the costing of spray drift testing. The measurement of spray drift in wind tunnels based on laser imaging is an evaluation method that can give one more choice for spraying drift testing. [ABSTRACT FROM AUTHOR]

Optical methods are widely used for medical diagnostic and therapeutic purposes. The use of laser source as non-ionized radiation in the imaging is considered safe, and has advantages more than the other radiological methods The laser application in imaging is based upon the detection and measuring the laser light parameters after passing through the turbid media of the tissue layers and the tumor mass to differentiate them precisely according to their different optical properties. In this experimental study, the tumor masses were implanted in the legs of ex-vivo mice. Then each leg was non-invasively scanned by NIR 785nm diode laser. The penetrated laser light power through the leg was measured. The results were tabulated and treated by using the Matlab program version R2013a (8.1.0.609) to create 2D image for the scanned tissue. The resulted images were clear. They showed precisely the imbedded tumor, its dimensions, and its location inside the tissue.

In this study, the performance of three phase-modulated signals used in airborne Synthetic Aperture Ladar (SAL) is investigated. The transmitting and receiving modes and imaging processing methods for these signals are studied. Considering that the swath of the airborne SAL is very narrow, in order to reduce the AD sampling rate of the wideband signal, a “phase-dechirping” receiving mode is proposed for the phase-modulated signal based on the Linear Frequency Modulation (LFM) signal. The imaging simulation results for these three phase-modulated signals validate the effectiveness of the proposed method.

Spray characteristics should be measured to understand fluid atomization. In this study, we investigated the atomization of kerosene fuel with low-flow-rate injectors in small rotary engines by use of optical diagnostic methods. Laser sheet scattering imaging and long-range microscopy were used to produce images of fuel sprays with high spatial and temporal resolutions. Digital image processing techniques were implemented to acquire the macroscopic characteristics of JP-8 jet fuel, such as tip penetration, droplet density distribution, and spray sheet profile. The effect of line pressure and Length-to-diameter ( L/ D) ratio on the global characteristics of the spray for two nozzles fitted on a high-frequency micro-dispensing system was also explored. The fuel injector was designed for low-flow-rate, low-pressure (less than 10 bar) applications. The local velocity of the fuel droplets was also measured by Particle image velocimetry (PIV). Results show that the decrease in L/ D ratio increases average velocity, spray sheet area, and angle. This effect becomes noticeable as the spray jet penetrates further downstream from the nozzle exit, except for tip velocity which drops quickly after the end of the injection pulse especially at high pressure levels. Small droplet diameters are produced in the case of low L/ D ratio and high line pressure. According to the PIV test, a connection exists between the tip velocity and velocity components at the central jet. [ABSTRACT FROM AUTHOR]

Rail surface defects such as the abrasion, scratch and peeling often cause damages to the train wheels and rail bearings. An efficient and accurate detection of rail defects is of vital importance for the safety of railway transportation. In the past few decades, automatic rail defect detection has been studied; however, most developed methods use optic-imaging techniques to collect the rail surface data and are still suffering from a high false recognition rate. In this paper, a novel 3D laser profiling system (3D-LPS) is proposed, which integrates a laser scanner, odometer, inertial measurement unit (IMU) and global position system (GPS) to capture the rail surface profile data. For automatic defect detection, first, the deviation between the measured profile and a standard rail model profile is computed for each laser-imaging profile, and the points with large deviations are marked as candidate defect points. Specifically, an adaptive iterative closest point (AICP) algorithm is proposed to register the point sets of the measured profile with the standard rail model profile, and the registration precision is improved to the sub-millimeter level. Second, all of the measured profiles are combined together to form the rail surface through a high-precision positioning process with the IMU, odometer and GPS data. Third, the candidate defect points are merged into candidate defect regions using the K-means clustering. At last, the candidate defect regions are classified by a decision tree classifier. Experimental results demonstrate the effectiveness of the proposed laser-profiling system in rail surface defect detection and classification. [ABSTRACT FROM AUTHOR]

Newly emerging accident-reducing, driver-assistance, and autonomous-navigation technology for automobiles is based on real-time three-dimensional mapping and object detection, tracking, and classification using lidar sensors. Yet, the lack of lidar sensors suitable for meeting application requirements appreciably limits practical widespread use of lidar in trucking, public livery, consumer cars, and fleet automobiles. To address this need, a system-engineering perspective to eyesafe lidar-system design for high-level advanced driverassistance sensor systems and a design trade study including 1.5-μm spot-scanned, line-scanned, and flashlidar systems are presented. A cost-effective lidar instrument design is then proposed based on high-repetitionrate diode-pumped solid-state lasers and high-gain, low-excess-noise InGaAs avalanche photodiode receivers and focal plane arrays. Using probabilistic receiver-operating-characteristic analysis, derived from measured component performance, a compact lidar system is proposed that is capable of 220 m ranging with 5-cm accuracy, which can be readily scaled to a 360-deg field of regard. [ABSTRACT FROM AUTHOR]

Textile logistic warehouses are highly automated mechanized places where control points are needed to count and validate the number of garments in each batch. This paper proposes and describes a low cost and small size automated system designed to count the number of garments by processing an image of the corresponding hanger hooks generated using an array of phototransistors sensors and a linear laser beam. The generated image is processed using computer vision techniques to infer the number of garment units. The system has been tested on two logistic warehouses with a mean error in the estimated number of hangers of 0.13%.

Art authentication is a complicated process that often requires the extensive study of high value objects. Although a series of non-destructive techniques is already available for art scientists, new techniques, extending current possibilities, are still required. In this paper, the use of a novel mid-infrared tunable imager is proposed as an active hyperspectral imaging system for art work analysis. The system provides access to a range of wavelengths in the electromagnetic spectrum (2500–3750 nm) which are otherwise difficult to access using conventional hyperspectral imaging (HSI) equipment. The use of such a tool could be beneficial if applied to the paint classification problem and could help analysts map the diversity of pigments within a given painting. The performance of this tool is demonstrated and compared with a conventional, off-the-shelf HSI system operating in the near infrared spectral region (900–1700 nm). Various challenges associated with laser-based imaging are demonstrated and solutions to these challenges as well as the results of applying classification algorithms to datasets captured using both HSI systems are presented. While the conventional HSI system provides data in which more pigments can be accurately classified, the result of applying the proposed laser-based imaging system demonstrates the validity of this technique for application in art authentication tasks.

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

Purpose: Percutaneous ablation under MRI-guidance allows treating otherwise inoperable liver tumors locally using a catheter probe. However, manually placing the probe is an error-prone and time consuming task that requires a considerable amount of training. The aim of this paper was to present a pneumatically actuated robotic instrument that can assist clinicians in MRI-guided percutaneous intervention of the liver and to assess its functionality in a clinical setting. The robot positions a needle-guide inside the MRI scanner bore and assists manual needle insertions outside the bore. Methods: The robot supports double oblique insertions that are particularly challenging for less experienced clinicians. Additionally, the system employs only standard imaging sequences and can therefore be used on different MRI scanners without requiring prior integration. The repeatability and the accuracy of the robot were evaluated with an optical tracking system. The functionality of the robot was assessed in an initial pilot study on two patients that underwent MRI-guided laser ablation of the liver. Results: The robot positioned the needle-guide in a repeatable manner with a mean error of 0.35 mm and a standard deviation of 0.32 mm. The mean position error corresponding to the needle tip, measured for an equivalent needle length of 195 mm over 25 fixed points, was 2.5 mm with a standard deviation of 1.2 mm. The pilot study confirmed that the robot does not interfere with the equipment used for MRI-guided laser ablation and does not visibly affect the MR images. The robot setup integrated seamlessly within the established clinical workflow. The robot-assisted procedure was successfully completed on two patients, one of which required a complex double oblique insertion. For both patients, the insertion depth and the tumor size were within the range reported for previous MRI-guided percutaneous interventions. A third patient initially enrolled in the pilot study and was considerably heavier than the others, preventing the use of the robot and requiring several freehand insertion attempts. Conclusions: The robot repeatability and accuracy are appropriate for liver tumors normally treated with MRI-guided ablation. The results of the pilot study endorse the clinical use of the robot in its current form: the robot is fully functional and MRI-compatible in a clinical setting and is suitable for double-oblique needle insertions. [ABSTRACT FROM AUTHOR]

Purpose: The practical use of the PRESAGE®solid plastic dosimeter is limited by the inconvenience of immersing it in high-viscosity oils to achieve refractive index matching for optical computed tomography (CT) scanning. The oils are slow to mix and difficult to clean from surfaces, and the dosimeter rotation can generate dynamic Schlieren inhomogeneity patterns in the reference liquid, limiting the rotational and overall scan speed. Therefore, it would be beneficial if lower-viscosity, water-based solutions with slightly unmatched refractive index could be used instead. The purpose of this work is to demonstrate the feasibility of allowing mismatched conditions when using a scanning laser system with a large acceptance angle detector. A fiducial-based ray path measurement technique is combined with an iterative CT reconstruction algorithm to reconstruct images. Methods: A water based surrounding liquid with a low viscosity was selected for imaging PRESAGE®solid dosimeters. Liquid selection was optimized to achieve as high a refractive index as possible while avoiding rotation-induced Schlieren effects. This led to a refractive index mismatch of 6% between liquid and dosimeters. Optical CT scans were performed with a fan-beam scanning-laser optical CT system with a large area detector to capture most of the refracted rays. A fiducial marker placed on the wall of a cylindrical sample occludes a given light ray twice. With knowledge of the rotation angle and the radius of the cylindrical object, the actual internal path of each ray through the dosimeter can be calculated. Scans were performed with 1024 projections of 512 data samples each, and rays were rebinned to form 512 parallel-beam projections. Reconstructions were performed on a 512 ? 512 grid using 100 iterations of the SIRT iterative CT algorithm. Proof of concept was demonstrated with a uniformly attenuating solution phantom. PRESAGE® dosimeters (11 cm diameter) were irradiated with Cobalt-60 irradiator to achieve either a uniform dose or a 2-level "step-dose" pattern. Results: With 6% refractive index mismatching, a circular field of view of 85% of the diameter of a cylindrical sample can be reconstructed accurately. Reconstructed images of the test solution phantom were uniform (within 3%) inside this radius. However, the dose responses of the PRESAGE® samples were not spatially uniform, with variations of at least 5% in sensitivity. The variation appears as a "cupping" artifact with less sensitivity in the middle than at the periphery of the PRESAGE® cylinder. Polarization effects were also detected for these samples. Conclusions: The fiducial-based ray path measurement scheme, coupled with an iterative reconstruction algorithm, enabled optical CT scanning of PRESAGE® dosimeters immersed in mismatched refractive index solutions. However, improvements to PRESAGE® dose response uniformity are required. [ABSTRACT FROM AUTHOR]

Purpose: It has long been known that age plays a crucial role in the deterioration of microvessels. The assessment of such deteriorations can be achieved by monitoring microvascular blood flow. Laser speckle contrast imaging (LSCI) is a powerful optical imaging tool that provides two-dimensional information on microvascular blood flow. The technique has recently been commercialized, and hence, few works discuss the postacquisition processing of laser speckle contrast images recorded in vivo. By applying entropy-based complexity measures to LSCI time series, we present herein the first attempt to study the effect of aging on microcirculation by measuring the complexity of microvascular signals over multiple time scales. Methods: Forearm skin microvascular blood flow was studied with LSCI in 18 healthy subjects. The subjects were subdivided into two age groups: younger (20-30 years old, n = 9) and older (50-68 years old, n = 9). To estimate age-dependent changes in microvascular blood flow, we applied three entropy-based complexity algorithms to LSCI time series. Results: The application of entropy-based complexity algorithms to LSCI time series can differentiate younger from older groups: the data fluctuations in the younger group have a significantly higher complexity than those obtained from the older group. Conclusions: The effect of aging on microcirculation can be estimated by using entropy-based complexity algorithms to LSCI time series. [ABSTRACT FROM AUTHOR]

This paper was focused on the synthesis and properties of a water-soluble resin having tertiary amine oxide side substituents. First, 3-(dimethylamino)propanoic acid was synthesized through the addition reaction of dimethylamine with methyl acrylate, followed by hydrolysis of the adduct. Then, 3-(dimethylamino)propanoic acid was oxidized with hydrogen peroxide to obtain 3-(dimethylamino)propanoic acid oxide. Finally, epoxy phenolic was reacted with 3-(dimethylamino)propanoic acid oxide to get the end product. Thermal behaviors and thermo-induced solubility change of the prepared resin were investigated. It was found that the tertiary amine oxide resin was still water soluble even after heating at 120 °C for 1 h. However, it readily became completely water insoluble after heating at 170 °C for a short period of time. Thin films were prepared with the aqueous solution of the tertiary amine oxide resin and an infrared (IR) dye with maximum absorption at 830 nm. The films could absorb 830 nm IR imaging radiation and give negative image after developing with neutral water. The water-soluble thermo-sensitive resin might be used in chemical-free thermal laser imaging applications. [ABSTRACT FROM AUTHOR]

Purpose: Microbeam radiation therapy (MRT) techniques are under investigation at synchrotrons worldwide. Favourable outcomes from animal and cell culture studies have proven the efficacy of MRT. The aim of MRT researchers currently is to progress to human clinical trials in the near future. The purpose of this study was to demonstrate the high resolution and 3D imaging of synchrotron generated microbeams in PRESAGE® dosimeters using laser fluorescence confocal microscopy. Methods:Water equivalent PRESAGE® dosimeters were fabricated and irradiated with microbeams on the Imaging and Medical Beamline at the Australian Synchrotron. Microbeam arrays comprised of microbeams 25-50 µm wide with 200 or 400 μm peak-to-peak spacing were delivered as single, cross-fire, multidirectional, and interspersed arrays. Imaging of the dosimeters was performed using a NIKON A1 laser fluorescence confocal microscope. Results: The spatial fractionation of the MRT beams was clearly visible in 2D and up to 9 mm in depth. Individual microbeams were easily resolved with the full width at half maximum of microbeams measured on images with resolutions of as low as 0.09 µm/pixel. Profiles obtained demonstrated the change of the peak-to-valley dose ratio for interspersed MRT microbeam arrays and subtle variations in the sample positioning by the sample stage goniometer were measured. Conclusions: Laser fluorescence confocal microscopy of MRT irradiated PRESAGE® dosimeters has been validated in this study as a high resolution imaging tool for the independent spatial and geometrical verification of MRT beam delivery. [ABSTRACT FROM AUTHOR]