Multiple Imaging System Research Articles

The contrast of demineralization on tooth occlusal surfaces from 405 to 1950-nm with varying depth.

Near Infrared Reflectance (NIR) is a new imaging technology that detects dental caries (decay) on tooth occlusal surfaces and in the interproximal contact sites between teeth. Conventional techniques, mostly dental x-rays, do not provide the high sensitivity and specificity at the vulnerable pits and fissure regions. The contrast of demineralization on tooth surfaces changes with increasing severity and the magnitude of that change with depth depends on the wavelength. The purpose of this study is to determine how the contrast changes with depth as a function of wavelength. Demineralization of varying depth was produced in 1.5 × 1.5 mm exposed windows after 1, 2, 3, 4, and 5 days of exposure to a demineralizing solution at pH 4.5. Lesions were imaged at 405, 630, 850, 1300, 1460, 1535, 1675, and 1950-nm with multiple imaging systems. The highest lesion contrast was measured at 1950-nm.

Analysis of the Data Consistency of Medical Imaging Information Systems: An Exploratory Study

In the context of medical imaging, a considerable amount of data is created on daily basis, which are produced and managed by multiple medical imaging and information systems. The professional and department performance, as well as the respective characterization, are supported by these data, which makes their quality a critical aspect to take into account. The work developed had the objective of analysing the existence of nonconformities related to the consistency of the Radiology Information Systems (RIS) and Picture and Communication System (PACS) databases, as well as their precision, accuracy, integrity and associated risks for the healthcare practice. Data belonging to 1068 computed radiography studies were analysed and ten nonconformities were identified, related to the patient name, patient age, patient date of birth, patient gender, study date, study time, institution identification, radiologist identification, number of radiographic projections performed, and billing code. The work carried out allowed identifying some lack of data quality, sometimes evidenced in the absence of consistency, precision, accuracy and integrity.

A Novel Wide Area Multiple Azimuth Beam ISAR Imaging System

A novel multiple azimuth beams (MAB) inverse synthetic aperture radar (ISAR) system, as well as, the corresponding processing algorithms are proposed in this paper, which is a promising technology for wide area surveillance (WAS). This system concept is intended to obtain wide area ISAR images of multiple moving targets, which would greatly increase the surveillance velocity range compared with the single beam system. The antenna transmits a sequence of high-gain and narrow radar beams to quickly scan a wide area, and receives the echoes from all the subswaths simultaneously. Two processing methods based on digital beamforming (DBF) are presented to separate the overlapped signals for achieving the wide area ISAR images. The performance of the proposed system is analyzed from the perspectives of the surveillance area, surveillance velocity range, and steering angle error. Finally, an exemplary ISAR system is presented and verified by the simulation experiments.

Wide-range and accurate particle sizing using extended interferometric particle imaging technique.

Accurate measurement of particles of a wide size range is generally difficult in interferometric particle imaging (IPI). We propose an extended IPI technique with double or multiple imaging systems of different scattering angles and polarizations to achieve a wider measurable size range. The effects of particle size, scattering angle, polarization, and the comprehensive parameters of the imaging system on fringe patterns are thoroughly discussed. In the case of measuring water droplets, the measurable size range of the extended IPI enlarges to 10 μm-1 mm, with high-quality fringe patterns favoring the accuracy of measurement. The relative deviations of extracted diameters are no greater than 9%, demonstrating good accuracy of the particle sizing using the extended IPI technique.

Crossover artifact in X-ray focusing imaging systems: K-edge subtraction imaging

The K-edge Subtraction (KES) imaging method is a very powerful synchrotron method which allows functional imaging of biological subjects. KES gives a simultaneous image of the contrast element and an anatomical image from the same data set. For biological subjects, an imaging system that uses focused multiple (two or more) x-ray energy beams to form the images, reduces motion artifact that can be misleading. However, the crossing of beams gives rise to another artifact, termed the “crossover” artifact, if the subject is not at the focus or is spatially extended around the focus. This artifact is addressed in this paper for KES which uses multiple x-ray energy focused beams. The development of multiple energy imaging systems have shown a great deal of utility in extracting multiple contrast materials. Nevertheless, the need for reduction of the crossover artifact is essential for the effective use of these systems for imaging of biological subjects, which will help prevent unnecessary re-imaging, reduce unusable images and dose to the subjects. A unified approach to modeling and reducing of crossover artifact in multiple x-ray energy KES is presented.

Computational coherent imaging by rotating a cylindrical lens.

To overcome longitudinal sampling rate fluctuation in axial multi-image computational imaging, an effortless and high-efficient optical scanning imaging system via the rotation of single cylindrical lens (RSCL) is proposed for reconstructing the amplitude and phase information of sample. Here the cylinder is a non-axial-symmetry phase modulator for generating diffracted intensity patterns. To determine the explicit rotation angle as a core parameter in the perfect reconstruction of the light field, two-step Radon transform (TsRT) is designed to obtain accurate rotation status of the cylindrical lens with diffraction patterns at the focal plane. All rotation operations are at a lateral plane for keeping the same scale in this multiple parameter computational imaging system. As a kind of scanning imaging approach, the experiment of RSCL is greatly simplified.

Reproducing two-dimensional mammograms with three-dimensional printed phantoms.

Mammography is currently the standard imaging modality used to screen women for breast abnormalities, and, as a result, it is a tool of great importance for the early detection of breast cancer. Physical phantoms are commonly used as surrogates of breast tissue to evaluate some aspects of the performance of mammography systems. However, most phantoms do not reproduce the anatomic heterogeneity of real breasts. New fabrication technologies, such as three-dimensional (3-D) printing, have created the opportunity to build more complex, anatomically realistic breast phantoms that could potentially assist in the evaluation of mammography systems. The reproducibility and relative low cost of 3-D printed objects might also enable the development of collections of representative patient models that could be used to assess the effect of anatomical variability on system performance, hence making bench testing studies a step closer to clinical trials. The primary objective of this work is to present a simple, easily reproducible methodology to design and print 3-D objects that replicate the attenuation profile observed in real two-dimensional mammograms. The secondary objective is to evaluate the capabilities and limitations of the competing 3-D printing technologies and characterize the x-ray properties of the different materials they use. Printable phantoms can be created using the open-source code introduced, which processes a raw mammography image to estimate the amount of x-ray attenuation at each pixel, and outputs a triangle mesh object that encodes the observed attenuation map. The conversion from the observed pixel gray value to a column of printed material with equivalent attenuation requires certain assumptions and knowledge of multiple imaging system parameters, such as x-ray energy spectrum, source-to-object distance, compressed breast thickness, and average breast material attenuation. To validate the proposed methodology, x-ray projections of printed phantoms were acquired with a clinical mammography system. The quality of the printing process was evaluated by comparing the mammograms of the printed phantoms and the original mammograms used to create the phantoms. The structural similarity index and the root-mean-square error were used as objective metrics to compare the two images. A detailed description of the software, a characterization of the printed materials using x-ray spectroscopy, and an evaluation of the realism of the sample printed phantoms are presented.

Constructing a 3D Multiple Mobile Medical Imaging System through Service Science, Management, Engineering and Design

Following the trend of using mobile devices for healthcare, a 3D multiple mobile medical imaging system (3D MMMIS) for doctor’s diagnosis and treatment was constructed through service science, management, engineering and design (SSMED) that can co-create the value between technology and humanity. Service experience engineering (SEE) methods were applied to a scenario of a doctors’ consultation, which is a deliberation of two or more healthcare doctors about diagnosis or treatment in particular cases. Proof of service was processed to test the prototype of the 3D MMMIS to check the doctors’ satisfaction with the innovative systems. Results show that doctors are satisfied with the 3D MMMIS. Conclusions suggested that the 3D MMMIS can be a helpful health technology for future healthcare.

Current State-of-the-Art 3D Tissue Models and Their Compatibility with Live Cell Imaging.

Mammalian cells grow within a complex three-dimensional (3D) microenvironment where multiple cells are organized and surrounded by extracellular matrix (ECM). The quantity and types of ECM components,alongside cell-to-cell and cell-to-matrix interactions dictate cellular differentiation, proliferation and function in vivo. To mimic natural cellular activities, various 3D tissue culture models have been established to replace conventional two dimensional (2D) culture environments. Allowing for both characterization and visualization of cellular activities within possibly bulky 3D tissue models presents considerable challenges due to the increased thickness and subsequent light scattering features of such 3D models. In this chapter, state-of-the-art methodologies used to establish 3D tissue models are discussed, first with a focus on both scaffold-free and scaffold-based 3D tissue model formation. Following on, multiple 3D live cell imaging systems, mainly optical imaging modalities, are introduced. Their advantages and disadvantages are discussed, with the aim of stimulating more research in this highly demanding research area.

Multiple energy synchrotron biomedical imaging system

A multiple energy imaging system that can extract multiple endogenous or induced contrast materials as well as water and bone images would be ideal for imaging of biological subjects. The continuous spectrum available from synchrotron light facilities provides a nearly perfect source for multiple energy x-ray imaging. A novel multiple energy x-ray imaging system, which prepares a horizontally focused polychromatic x-ray beam, has been developed at the BioMedical Imaging and Therapy bend magnet beamline at the Canadian Light Source. The imaging system is made up of a cylindrically bent Laue single silicon (5,1,1) crystal monochromator, scanning and positioning stages for the subjects, flat panel (area) detector, and a data acquisition and control system. Depending on the crystal’s bent radius, reflection type, and the horizontal beam width of the filtered synchrotron radiation (20–50 keV) used, the size and spectral energy range of the focused beam prepared varied. For example, with a bent radius of 95 cm, a (1,1,1) type reflection and a 50 mm wide beam, a 0.5 mm wide focused beam of spectral energy range 27 keV–43 keV was obtained. This spectral energy range covers the K-edges of iodine (33.17 keV), xenon (34.56 keV), cesium (35.99 keV), and barium (37.44 keV); some of these elements are used as biomedical and clinical contrast agents. Using the developed imaging system, a test subject composed of iodine, xenon, cesium, and barium along with water and bone were imaged and their projected concentrations successfully extracted. The estimated dose rate to test subjects imaged at a ring current of 200 mA is 8.7 mGy s−1, corresponding to a cumulative dose of 1.3 Gy and a dose of 26.1 mGy per image. Potential biomedical applications of the imaging system will include projection imaging that requires any of the extracted elements as a contrast agent and multi-contrast K-edge imaging.

TU-FG-209-06: Quantitative Evaluation of the Temporal Performance of Clinical Fluoroscopic Imaging Systems: The Temporal Modulation Transfer Function (TMTF)

Purpose: Measure the temporal modulation transfer function (TMTF) of clinical fluoroscopic flat panel imaging systems in order to accurately quantify their performance for temporally sensitive clinical tasks. Methods: Copper blades (0.76 mm thick, 6 cm radius) with precision-machined edges were manufactured and mounted on a voltage regulated DC motor apparatus. Images were acquired with the blade apparatus positioned at the center of the detector matrix and set in motion at a constant rotational velocity (0.66 Hz), thereby creating a rotating radio-opaque edge in both space and time. The spatio-temporal edge response function was analyzed using a single frame from the acquired image sequence. Image processing included semi-automatic detection of the center of rotation, rebinning the pixels into subsampled polar coordinates, and deconvolving the TMTF from the previously measured spatial MTF. The analysis returned the presampled TMTF. This method was applied to multiple fluoroscopic imaging systems. Results: Initial experiments measured the TMTF of a typical fluoroscopy unit (Philips Allura Xper FD20) using cine acquisition (60.7 kVp, 6 fps, 42.6 ms pulse-width). For this system and protocol, the measured TMTF closely matched an idealized sinc function corresponding to the Fourier transform of the measured rectangular x-ray pulse-width. Within the frequency range of 0 – 47 Hz, the measured TMTF and ideal sinc function were compared at 1.46 Hz intervals. The differences measured varied within [-0.0164, 0.0324] with a root-mean-square (rms) difference of 0.0201. These particular results suggest that very little degradation in temporal performance is attributable to the imaging hardware, but rather the measured performance is dominated by the acquisition protocol parameters, namely pulse-width and frames-per-second. Conclusion: This method provides a clinically tractable and accurate measurement of the TMTF. Ongoing experiments are investigating the impact of different fluoroscopy systems, image processing, and protocol choice on the measured TMTF.

EP-1909: Quantitative and qualitative assessment of thoracic CBCT image quality for multiple imaging systems

EP-1909: Quantitative and qualitative assessment of thoracic CBCT image quality for multiple imaging systems

Coded aperture optimization for compressive X-ray tomosynthesis.

Radiation dose is a concern in X-ray tomographic imaging; coded aperture compressive X-ray tomosynthesis is an approach used to reduce radiation. It places a coded aperture in front of an X-ray source in order to obtain 2D patterned projections of a three-dimensional object onto a detector plane. By using different coded apertures in a multiple source system, multiplexed projections can be obtained instead of sequential projections as in conventional tomosynthesis systems. Compressed sensing (CS) reconstruction algorithms are then used to recover the three-dimensional data cube. An optimization approach to design the structure of the coded apertures in a multiple source compressive X-ray tomosynthesis imaging system is presented. A uniform energy criteria on the voxels and detector elements is used so that the object is uniformly sensed and the elements of the detector plane uniformly sense the information. Simulations and experimental results for optimized coded apertures are shown, and their performance is compared to the use of random coded apertures.

WE‐G‐204‐07: Automated Characterization of Perceptual Quality of Clinical Chest Radiographs: Improvements in Lung, Spine, and Hardware Detection

Purpose:To develop and validate more robust methods for automated lung, spine, and hardware detection in AP/PA chest images. This work is part of a continuing effort to automatically characterize the perceptual image quality of clinical radiographs. [Y. Lin et al. Med. Phys. 39, 7019–7031 (2012)]Methods:Our previous implementation of lung/spine identification was applicable to only one vendor. A more generalized routine was devised based on three primary components: lung boundary detection, fuzzy c‐means (FCM) clustering, and a clinically‐derived lung pixel probability map. Boundary detection was used to constrain the lung segmentations. FCM clustering produced grayscale‐ and neighborhood‐based pixel classification probabilities which are weighted by the clinically‐derived probability maps to generate a final lung segmentation. Lung centerlines were set along the left‐right lung midpoints. Spine centerlines were estimated as a weighted average of body contour, lateral lung contour, and intensity‐based centerline estimates. Centerline estimation was tested on 900 clinical AP/PA chest radiographs which included inpatient/outpatient, upright/bedside, men/women, and adult/pediatric images from multiple imaging systems. Our previous implementation further did not account for the presence of medical hardware (pacemakers, wires, implants, staples, stents, etc.) potentially biasing image quality analysis. A hardware detection algorithm was developed using a gradient‐based thresholding method. The training and testing paradigm used a set of 48 images from which 1920 51×51 pixel2 ROIs with and 1920 ROIs without hardware were manually selected.Results:Acceptable lung centerlines were generated in 98.7% of radiographs while spine centerlines were acceptable in 99.1% of radiographs. Following threshold optimization, the hardware detection software yielded average true positive and true negative rates of 92.7% and 96.9%, respectively.Conclusion:Updated segmentation and centerline estimation methods in addition to new gradient‐based hardware detection software provide improved data integrity control and error‐checking for automated clinical chest image quality characterization across multiple radiography systems.

Development of Multiple-Frequency Ultrasonic Imaging System Using Multiple Resonance Piezoelectric Transducer

The authors have developed a multiple frequency imaging system using a multiple resonance transducer (MRT) consisting of 1–3 composite materials with a low mechanical quality factor Q bonded together. The MRT has a structure consisting of thin and thick piezoelectric plates, two matching layers, and a backing layer. This makes it possible to obtain B-mode images of satisfactory resolution using ultrasonic pulses owing to their short duration. In this paper, the vibration property of the MRT derived through equivalent-circuit analysis is first shown. By utilizing the result, an MRT capable of transmitting ultrasonic pulses for generation of the images of biological tissues with satisfactory resolution is designed and prototyped. Setting the prototype transducer in the mechanical sector probe of commercial ultrasonic diagnosis equipment, the speckle reduction effect is demonstrated using images of various phantoms to mimic biological tissues and a human thyroid.

3E5-1 Development of Multiple Frequency Ultrasonic Imaging System by Using Multi-Resonance Piezoelectric Transducer(Medical Ultrasound)

3E5-1 Development of Multiple Frequency Ultrasonic Imaging System by Using Multi-Resonance Piezoelectric Transducer(Medical Ultrasound)

Halftone moiré due to imager distortion

Moire in color printing is an undesirable visible artifact that can arise from overlaying multiple halftone color separations. Halftone geometric configurations designed to avoid moire in the overlays strictly require that individual halftone color separations must possess a low degree of relative distortion. However, optical and mechanical errors of multiple imaging systems within a printer usually produce differences between the color planes in the trajectory and placement of the exposure spots. We study color halftone moire due to these optical and mechanical errors for otherwise moire-free halftone configurations. Distortions due to commonly used imaging systems in xerography (i.e., raster output scanners and image bars) are categorized into two classes that depend on the direction of the displacement errors [i.e., process direction distortions (such as shear, bow, and skew) and cross-process direction distortions (such as scanline magnification, magnification imbalance, and high-order scanline distortions)]. Using frequency vector representation of color halftones, we derive analytical expressions for acceptability bounds on these distortions. We evaluate the analytical expressions for a classical halftone screen configuration and a minimum rosette geometry to enable specification allocations for different imaging components in the design of an imaging system.

Distributed aperture synthesis

Distributed aperture synthesis is an exciting technique for recovering high-resolution images from an array of small telescopes. Such a system requires optical field values measured at individual apertures to be phased together so that a single, high-resolution image can be synthesized. This paper describes the application of sharpness metrics to the process of phasing multiple coherent imaging systems into a single high-resolution system. Furthermore, this paper will discuss hardware and present the results of simulations and experiments which will illustrate how aperture synthesis is performed.

Fluorescence detection and imaging of cytosolic calcium oscillations: A comparison of four equipment setups

The increase in cytosolic calcium concentration has been shown to play an important role in vital cellular functions such as muscle contraction, cell secretion, oocyte fertilization, nerve conduction, embryo development and apoptosis in animals, plants and microbes, and in the invasion of mammalian cells by parasites, bacteria, and viruses. Therefore, live cell imaging of increases in cytosolic calcium concentration in cellular compartments has been investigated intensively. Multiple calcium imaging systems are now available commercially, but when it comes to deciding which model to purchase, it is often hard to obtain enough information for an optimal setup. In this paper, a comparison was made among four fluorescent detection/imaging devices for the detection of cytosolic calcium oscillations induced in rat pancreatic acinar cells by cholecystokinin and in hepatocytes by phenylephrine. Detailed equipment setup, differences in data acquisition and analysis, and side effects of the excitation light on live cells were analyzed. A list of important factors that should be considered in choosing the optimal equipment are recommended, which will be useful for users of such devices in the future.

Large refractive index modulation tilted holographic planar structured grating based on dichromated gelatin

A new type grating, tilted holographic planar structured dichromated gelatin (DCG) grating with large refractive index modulation, is presented in this paper. The grating is inscribed by superposing two coherent laser beams from the front and the thin side surfaces, respectively. The relationship between the tilted angle and the three types of coupling modes is analyzed when coupling with fiber. Besides, the couple mode theory and experimental investigation are applied on major characteristics analysis of the radiation mode DCG grating of tilted angle 45°. Due to the tilted planar structured grating has large refractive index modulation, it not only offers convenience for connecting (or integrating) with other fiber or waveguide-based devices, but also provide some special characteristics such as low wavelength selectivity (which is required for some applications such as multiple spectrum biomedical imaging). Therefore, this unique grating device has a wide application in optical fields such as for the waveguide-based, parallel, multiple spectrum imaging system.