Low-cost Imaging System Research Articles

22pm1-F6 感温塗料を用いた赤外線熱イメージングデバイスのためのディジタルフィルタの開発

This paper reports a digital noise reduction method for a low-cost thermal imaging system using IR-to-visible transducers. Due to the weak intensity of luminescence from the transducers, an optical measurement method used in the system produces relatively large noise. To reduce the noise without any hardware modification, two digital filters, one of which is based on a finite impulse response filter and the other is based on a Kalman filter, were proposed and applied to the thermal imaging system. Both filters could successfully reduce the noise in the thermal image, however the Kalman filtered result had higher time response, which is more suitable for the real-time thermal imaging.

Noncontact monitoring of vascular lesion phototherapy efficiency by RGB multispectral imaging

A prototype low-cost RGB imaging system consisting of a commercial RGB CMOS sensor, RGB light-emitting diode ring light illuminator, and a set of polarizers was designed and tested for mapping the skin erythema index, in order to monitor skin recovery after phototherapy of vascular lesions, such as hemangiomas and telangiectasias. The contrast of erythema index (CEI) was proposed as a parameter for quantitative characterization of vascular lesions. Skin recovery was characterized as a decrease of the CEI value relative to the value before the treatment. This approach was clinically validated by examining 31 vascular lesions before and after phototherapy.

Low-cost Gel Imaging System Implementation in Reduced Size

In this paper, we proposed a method for configuring each component of a gel documentation system for the miniaturization and penetration of the system. To miniaturize the UV illuminator part, the minimum type of UVB lamp was adopted along with ballasts that can drive four lamps. As the imaging system, a conventional compact digital camera, which has a similar performance to that of a DSLR, was adopted. By developing and supplementing the PC remote control function of which lack in the low-end digital camera, the price and size of the gel doc equipment can be significantly reduced while still maintaining the performance and function of the gel doc. The proposed system showed comparable performance and image quality to those of the existing Gel documentation system even though if it was small and inexpensive.

High Resolution Retinal Imaging Based on Ocular Aberration Measurement and Compensation

Ocular retinal imaging is a major diagnostic modality for retinal disease, and can play a critical role for diagnosing systemic diseases such as diabetes and eye-specific diseases such as macular degeneration and diabetic retinopathy, the leading causes of blindness. In order to get high-resolution retinal imaging and develop the low-cost and compact retinal imaging system, we employ micro adaptive optics, which is consisted of wavefront sensor, wavefront corrector and control system. In this paper, the theory, design and testing of the ocular retinal microscopy is detailed, with an emphasis on the eye wavefront aberration describing, aberration detecting method with Hartmann-Shack wavefront sensing and close-loop aberration compensating by micromachined membrane deformable mirrors(MMDM).The ocular retinal microscopy experimental setup is built, the retinal cell imaging had been snapped. It is showed in this work that the ocular retinal microscopy based on adaptive optics system can enable diffraction-limited imaging of micro-scale features of the retina, through real-time compensation of aberrations introduced by the eye.

휴대용 초음파진단기를 위한 펄스 도플러 갭 필링 알고리즘의 개선

In this paper, we studied on Doppler gap-filling algorithms suitable for a portable or low-cost medical ultrasound imaging system, and as a result, found out algorithms based on mirroring or autoregressive model. Moreover, controlling the computational demand in the proper range, we improved the performances of these algorithms by solving their problems. Effectiveness of these modified algorithms is verified by computer simulations and experiments which used artificially generated Doppler signals and Doppler data acquired from human body through an actual ultrasound system.

DATA ACQUISITION THROUGH THE MODEL AIRCRAFT FOR MAPPING PURPOSES

Abstract. Photogrammetry and remote sensing have become indispensable in today's surveying with the emerging technologies. Some difficulties are being experienced in applications due to the incredible advances in imaging systems and increasing complexity of carrier platforms, used, in parallel with them. In this context, the most agreeable approach is the achievement of desired precision proportional with the requirements in shorter time span and the reduction of cost utilizing the most suitable mapping platform with basic systems. Towards these aims, a model aircraft, containing a non-metric camera, capturing images for mapping purposes, is considered to be employed in this study. Thus, this will lead to emerge a low cost imaging system. Within the study, besides using a high resolution digital non-metric camera and a carrier model aircraft, the previously produced maps of test field, derived from aerial photos, were used to conduct the analysis. The scope of this study is the integration of a model aircraft and a non-metric camera for mapping purposes to reduce very costly and time consuming photogrammetric map production for narrower areas. Also this will give rise to a method for the achievement of high cost aims with lower budgets. Using a model aircraft, instead of a real one, gives us an upper hand in repeating measurements anytime, desired, so that analyses can be made for the works that undergoes temporal changes. According to the aims of the study, a stereo model has been generated for the extraction of details from aerial photos, taken by the non-metric camera. Estimated results have been compared with 1/1000 scaled maps from photogrammetry and figured out their validity for using in narrower areas with high accuracy.

An automatic compact Schlieren imaging system for ultrasound transducer testing

The current standard used for the characterization of ultrasonic transducers is the hydrophonic technique, which is able to measure the acoustic pressure profile. This technique allows a quantitative analysis, but is marred by several problems. A scan of the region of interest is a time-consuming operation, especially when measuring a long acoustic beam. Furthermore, a hydrophone placed near the radiating surface is certainly an impediment to the free propagation of the field. Off-axis measurements can be inaccurate because of the angular response of the hydrophone. These problems, together with the costs, have encouraged the search for an alternative quick and inexpensive test system. The well-known Schlieren technique allows a real-time visualization of the whole pressure range of the transducers, but to display the entire beam emitted by the transducers it is necessary to use very large-diameter lenses, with focal lengths of several meters. Such systems are very cumbersome and difficult to use. The system developed in this paper allows the imaging of an acoustic beam up to 200 mm in length, but the system is compact, being only about 1 m long and 0.30 m wide. A similar system based on the classic Schlieren effect would be several meters long, with lenses of 200 mm in diameter. Finally, the system can reconstruct the section of the beam at any height, using an acoustic tomography technique, and can also implement a quantitative analysis. Because it uses only commercial components, the developed and fabricated ultrasonic beam analyzer is a very low-cost imaging system. The goal of this work is to create a compact, low-cost system based on this technique to test a wide range of ultrasonic transducers up to 40 MHz and above.

Low-Cost High-Speed Imaging System for Observing Vocal Fold Vibration in Voice Disorders

Purpose: The aim of this study was to establish a method to observe vocal fold vibration using a low-cost high-speed laryngeal imaging system. Procedures: We assembled a high-speed imaging system with a consumer digital camera and a rigid laryngeal endoscope. The camera can shoot digital images at a rate of 1,200 frames per second and be purchased for about USD 1,000 in Japan. Results: We examined the normal and pathological vocal folds of 215 subjects with our new system and analyzed the vocal fold vibration in these subjects by playback of a video and kymograph images. Conclusions: Our high-speed laryngeal imaging system is highly cost-effective and can be a useful tool for examining the vocal folds of patients with voice disorders.

A polymer microfluidic chip for quantitative detection of multiple water- and foodborne pathogens using real-time fluorogenic loop-mediated isothermal amplification

Inexpensive, portable, and easy-to-use devices for rapid detection of microbial pathogens are needed to ensure safety of water and food. In this study, a disposable polymer microfluidic chip for quantitative detection of multiple pathogens using isothermal nucleic acid amplification was developed. The chip contains an array of 15 interconnected reaction wells with dehydrated primers for loop-mediated isothermal amplification (LAMP), and requires only a single pipetting step for dispensing of sample. To improve robustness of loading and amplification, hydrophobic air vents and microvalves were monolithically integrated in the multi-layered structure of the chip using an inexpensive knife plotter. For quantification, LAMP was performed with a highly fluorescent DNA binding dye (SYTO-82) and the reactions monitored in real-time using a low-cost fluorescence imaging system previously developed by our group (Ahmad et al., Biomed. Microdevices 13(5), 929-937). Starting from genomic DNA mixtures, the chip was successfully evaluated for rapid analysis of multiple virulence and marker genes of Salmonella, Campylobacter jejuni, Shigella, and Vibrio cholerae, enabling detection and quantification of 10-100 genomes per μl in less than 20 min. It is anticipated that the microfluidic chip, along with the real-time imaging system, may be a key enabling technology for developing inexpensive and portable systems for on-site screening of multiple pathogens relevant to food and water safety.

Low-cost multispectral vegetation imaging system for detecting leaking CO2 gas

As a component of a multisensor approach to monitoring carbon sequestration sites for possible leaks of the CO₂ gas from underground reservoirs, a low-cost multispectral imaging system has been developed for indirect detection of gas leaks through observations of the resulting stress in overlying vegetation. The imager employs front-end optics designed to provide a full 50° field of view with a small, low-cost CMOS detector, while still maintaining quasi-collimated light through the angle-dependent interference filters used to define the spectral bands. Red and near-infrared vegetation reflectances are used to compute the normalized difference vegetation index (NDVI) and spatial and temporal patterns are analyzed statistically to identify regions of anomalous stress, which are then flagged for closer inspection with in-situ CO₂ sensors. The system is entirely self-contained with an onboard compact computer and is housed in a weather-proof housing to enable extended outdoor deployment.

WormAssay: A Novel Computer Application for Whole-Plate Motion-based Screening of Macroscopic Parasites

Lymphatic filariasis is caused by filarial nematode parasites, including Brugia malayi. Adult worms live in the lymphatic system and cause a strong immune reaction that leads to the obstruction of lymph vessels and swelling of the extremities. Chronic disease leads to the painful and disfiguring condition known as elephantiasis. Current drug therapy is effective against the microfilariae (larval stage) of the parasite, but no drugs are effective against the adult worms. One of the major stumbling blocks toward developing effective macrofilaricides to kill the adult worms is the lack of a high throughput screening method for candidate drugs. Current methods utilize systems that measure one well at a time and are time consuming and often expensive. We have developed a low-cost and simple visual imaging system to automate and quantify screening entire plates based on parasite movement. This system can be applied to the study of many macroparasites as well as other macroscopic organisms.

A CCD-based fluorescence imaging system for real-time loop-mediated isothermal amplification-based rapid and sensitive detection of waterborne pathogens on microchips

Rapid, sensitive, and low-cost pathogen diagnostic systems are needed for early disease diagnosis and treatment, especially in resource-limited settings. This study reports a low-cost charge-coupled device (CCD)-based fluorescence imaging system for rapid detection of waterborne pathogens by isothermal gene amplification in disposable microchips. Fluorescence imaging capability of this monochromatic CCD camera is evaluated by optimizing the gain, offset, and exposure time. This imaging system is validated for 12 virulence genes of major waterborne pathogens on cyclic olefin polymer (COP) microchips, using SYTO-82 dye and real time fluorescence loop-mediated isothermal amplification referred here as microRT(f)-LAMP. Signal-to-noise ratio (SNR) and threshold time (Tt) of microRT(f)-LAMP assays are compared with those from a commercial real-time polymerase chain reaction (PCR) instrument. Applying a CCD exposure of 5 s to 10(5) starting DNA copies of microRT(f)-LAMP assays increases the SNR by 8-fold and reduces the Tt by 9.8 min in comparison to a commercial real-time PCR instrument. Additionally, single copy level sensitivity for Campylobacter jejuni 0414 gene is obtained for microRT(f)-LAMP with a Tt of 19 min, which is half the time of the commercial real-time PCR instrument. Due to the control over the exposure time and the wide field imaging capability of CCD, this low-cost fluorescence imaging system has the potential for rapid and parallel detection of pathogenic microorganisms in high throughput microfluidic chips.

Design and Development of a Multi-Purpose Low-Cost Hyperspectral Imaging System

Hyperspectral image analysis is gaining momentum in a wealth of natural resources and agricultural applications facilitated by the increased availability of low-cost imaging systems. In this study, we demonstrate the development of the Vegetation Mobile Mapping System (VMMS), a low-cost hyperspectral sensing system that is supported by consumer-grade digital camera(s). The system was developed using off-the-shelf imaging and navigation components mainly for ground-based applications. The system integrates a variety of components including timing and positioning GPS receivers and an Inertial Measurement Unit (IMU). The system was designed to be modular and interoperable allowing the imaging components to be used with different navigation systems. The technique used for synchronizing captured images with GPS time was presented. A relative radiometric calibration technique utilizing images of homogeneous targets to normalize pixel gain and offset parameters was used. An empirical spectral calibration method was used to assign wavelengths to image bands. Data acquisition parameters to achieve appropriate spatial coverage were presented. The system was tested in ground-based data collection and analysis experiments that included water quality and vegetation studies.

A 3D Freehand Ultrasound System for Multi-view Reconstructions from Sparse 2D Scanning Planes

BackgroundA significant limitation of existing 3D ultrasound systems comes from the fact that the majority of them work with fixed acquisition geometries. As a result, the users have very limited control over the geometry of the 2D scanning planes.MethodsWe present a low-cost and flexible ultrasound imaging system that integrates several image processing components to allow for 3D reconstructions from limited numbers of 2D image planes and multiple acoustic views. Our approach is based on a 3D freehand ultrasound system that allows users to control the 2D acquisition imaging using conventional 2D probes.For reliable performance, we develop new methods for image segmentation and robust multi-view registration. We first present a new hybrid geometric level-set approach that provides reliable segmentation performance with relatively simple initializations and minimum edge leakage. Optimization of the segmentation model parameters and its effect on performance is carefully discussed. Second, using the segmented images, a new coarse to fine automatic multi-view registration method is introduced. The approach uses a 3D Hotelling transform to initialize an optimization search. Then, the fine scale feature-based registration is performed using a robust, non-linear least squares algorithm. The robustness of the multi-view registration system allows for accurate 3D reconstructions from sparse 2D image planes.ResultsVolume measurements from multi-view 3D reconstructions are found to be consistently and significantly more accurate than measurements from single view reconstructions. The volume error of multi-view reconstruction is measured to be less than 5% of the true volume. We show that volume reconstruction accuracy is a function of the total number of 2D image planes and the number of views for calibrated phantom. In clinical in-vivo cardiac experiments, we show that volume estimates of the left ventricle from multi-view reconstructions are found to be in better agreement with clinical measures than measures from single view reconstructions.ConclusionsMulti-view 3D reconstruction from sparse 2D freehand B-mode images leads to more accurate volume quantification compared to single view systems. The flexibility and low-cost of the proposed system allow for fine control of the image acquisition planes for optimal 3D reconstructions from multiple views.

Low-cost three-dimensional imaging system combining fluorescence and ultrasound

In this paper, we present a dual-modality imaging system combining three-dimensional (3D) continuous-wave transillumination fluorescence tomography with 3D ultrasound (US) imaging. We validated the system with two phantoms, one containing fluorescent inclusions (Cy5.5) at different depths, and another varying-thickness semicylindrical phantom. Using raster scanning, the combined fluorescence/US system was used to collect the boundary fluorescent emission in the X-Y plane, as well as recovered the 3D surface and position of the inclusions from US signals. US images were segmented to provide soft priors for the fluorescence image reconstruction. Phantom results demonstrated that with priors derived from the US images, the fluorescent reconstruction quality was significantly improved. As further evaluation, we show pilot in vivo results using an Apo-E mouse to assess the feasibility and performance of this system in animal studies. Limitations and potential to be used in artherosclerosis studies are then discussed.

A Low-Cost Implantable Near-Infrared Imaging System of Spinal Cord Activity in the Cat

A low-cost device using diffuse optical imaging (DOI) for measuring in vivo hemodynamic changes in the spinal cord has been developed. The proposed system is aimed at monitoring for the first time real-time hemodynamic changes associated with intraspinal rhythmic motor activity monitored by electroneurogram (ENG) evoked in paralyzed cats (fictive locomotion). The device contains the emitting and collecting probes within a saddle that fits over a vertebra and has been developed with discrete component circuits. Experiments performed in two acutely decerebrate and paralyzed cats confirm a noticeable and reproducible hemodynamic response during episodes of fictive locomotion. The device is designed so that it could be implanted chronically. In the future, a multi-implant imaging platform could measure long-term hemodynamic changes in the spinal cord.

Improvement of AC-based Electrical Capacitance Tomography Hardware

Electrical Capacitance Tomography (ECT) is used to obtain the permittivity distribution of material, measuring capacitances between electrodes, placed around material. ECT is fast, non-invasive and low cost imaging system. A particular difficulty with capacitance measurement of an ECT hardware is to measure small capacitance changes between electrodes of sensors having large stray and standing capacitances. This paper presents an improved design of AC-based ECT hardware. Presented hardware is more stable, flexible, effective and suitable for electrical conductance tomography also. New concepts for hardware design and measurement algorithm are presented and proved by simulation.

A low-cost, portable, and quantitative spectral imaging system for application to biological tissues

The ability of diffuse reflectance spectroscopy to extract quantitative biological composition of tissues has been used to discern tissue types in both pre-clinical and clinical cancer studies. Typically, diffuse reflectance spectroscopy systems are designed for single-point measurements. Clinically, an imaging system would provide valuable spatial information on tissue composition. While it is feasible to build a multiplexed fiber-optic probe based spectral imaging system, these systems suffer from drawbacks with respect to cost and size. To address these we developed a compact and low cost system using a broadband light source with an 8-slot filter wheel for illumination and silicon photodiodes for detection. The spectral imaging system was tested on a set of tissue mimicking liquid phantoms which yielded an optical property extraction accuracy of 6.40 +/- 7.78% for the absorption coefficient (micro(a)) and 11.37 +/- 19.62% for the wavelength-averaged reduced scattering coefficient (micro(s)').

Evaluation of a low-cost, portable imaging system for early detection of oral cancer

BackgroundThere is an important global need to improve early detection of oral cancer. Recent reports suggest that optical imaging technologies can aid in the identification of neoplastic lesions in the oral cavity; however, there is little data evaluating the use of optical imaging modalities in resource limited settings where oral cancer impacts patients disproportionately. In this article, we evaluate a simple, low-cost optical imaging system that is designed for early detection of oral cancer in resource limited settings. We report results of a clinical study conducted at Tata Memorial Hospital (TMH) in Mumbai, India using this system as a tool to improve detection of oral cancer and its precursors.MethodsReflectance images with white light illumination and fluorescence images with 455 nm excitation were obtained from 261 sites in the oral cavity from 76 patients and 90 sites in the oral cavity from 33 normal volunteers. Quantitative image features were used to develop classification algorithms to identify neoplastic tissue, using clinical diagnosis of expert observers as the gold standard.ResultsUsing the ratio of red to green autofluorescence, the algorithm identified tissues judged clinically to be cancer or clinically suspicious for neoplasia with a sensitivity of 90% and a specificity of 87%.ConclusionsResults suggest that the performance of this simple, objective low-cost system has potential to improve oral screening efforts, especially in low-resource settings.

A real-time monitoring system for adherently grown cells

We present a real-time, compact and low-cost imaging system for cell cultures grown attached in standard disposable multi-well plates. The system comprises a custom made platform to position a standard multi-well plate and a 1/4” CCD image sensor aligned, fixed and focused directly at the bottom of the well of interest. The image sensor has a resolution of 640×480 pixels. With a lens mounted on top of the CCD sensor we obtained a 3.26×2.45 mm2 field of view, corresponding to a pixel size of about 5 μm. With our imaging system we have successfully observed adherent epithelial cells (A549): individually, in spheroid shaped cluster, and in a wound healing assay.