About: Imaging phantom is a(n) research topic. Over the lifetime, 28170 publication(s) have been published within this topic receiving 510003 citation(s). The topic is also known as: phantom.
Papers published on a yearly basis
01 Apr 1991-Ultrasonic Imaging
TL;DR: Initial results of several phantom and excised animal tissue experiments are reported which demonstrate the ability of this technique to quantitatively image strain and elastic modulus distributions with good resolution, sensitivity and with diminished speckle.
Abstract: We describe a new method for quantitative imaging of strain and elastic modulus distributions in soft tissues. The method is based on external tissue compression, with subsequent computation of the strain profile along the transducer axis, which is derived from cross-correlation analysis of pre- and post-compression A-line pairs. The strain profile can then be converted to an elastic modulus profile by measuring the stresses applied by the compressing device and applying certain corrections for the nonuniform stress field. We report initial results of several phantom and excised animal tissue experiments which demonstrate the ability of this technique to quantitatively image strain and elastic modulus distributions with good resolution, sensitivity and with diminished speckle. We discuss several potential clinical uses of this technique.
TL;DR: The authors present a realistic, high-resolution, digital, volumetric phantom of the human brain, which can be used to simulate tomographic images of the head and is the ideal tool to test intermodality registration algorithms.
Abstract: After conception and implementation of any new medical image processing algorithm, validation is an important step to ensure that the procedure fulfils all requirements set forth at the initial design stage. Although the algorithm must be evaluated on real data, a comprehensive validation requires the additional use of simulated data since it is impossible to establish ground truth with in vivo data. Experiments with simulated data permit controlled evaluation over a wide range of conditions (e.g., different levels of noise, contrast, intensity artefacts, or geometric distortion). Such considerations have become increasingly important with the rapid growth of neuroimaging, i.e., computational analysis of brain structure and function using brain scanning methods such as positron emission tomography and magnetic resonance imaging. Since simple objects such as ellipsoids or parallelepipedes do not reflect the complexity of natural brain anatomy, the authors present the design and creation of a realistic, high-resolution, digital, volumetric phantom of the human brain. This three-dimensional digital brain phantom is made up of ten volumetric data sets that define the spatial distribution for different tissues (e.g., grey matter, white matter, muscle, skin, etc.), where voxel intensity is proportional to the fraction of tissue within the voxel. The digital brain phantom can be used to simulate tomographic images of the head. Since the contribution of each tissue type to each voxel in the brain phantom is known, it can be used as the gold standard to test analysis algorithms such as classification procedures which seek to identify the tissue "type" of each image voxel. Furthermore, since the same anatomical phantom may be used to drive simulators for different modalities, it is the ideal tool to test intermodality registration algorithms. The brain phantom and simulated MR images have been made publicly available on the Internet (http://www.bic.mni.mcgill.ca/brainweb).
TL;DR: A method for obtaining a high-resolution image of magnetic tracers that takes advantage of the nonlinear magnetization curve of small magnetic particles and has the potential to be developed into an imaging method characterized by both high spatial resolution as well as high sensitivity.
Abstract: The use of contrast agents and tracers in medical imaging has a long history. They provide important information for diagnosis and therapy, but for some desired applications, a higher resolution is required than can be obtained using the currently available medical imaging techniques. Consider, for example, the use of magnetic tracers in magnetic resonance imaging: detection thresholds for in vitro and in vivo imaging are such that the background signal from the host tissue is a crucial limiting factor. A sensitive method for detecting the magnetic particles directly is to measure their magnetic fields using relaxometry; but this approach has the drawback that the inverse problem (associated with transforming the data into a spatial image) is ill posed and therefore yields low spatial resolution. Here we present a method for obtaining a high-resolution image of such tracers that takes advantage of the nonlinear magnetization curve of small magnetic particles. Initial 'phantom' experiments are reported that demonstrate the feasibility of the imaging method. The resolution that we achieve is already well below 1 mm. We evaluate the prospects for further improvement, and show that the method has the potential to be developed into an imaging method characterized by both high spatial resolution as well as high sensitivity.
01 Jan 1994
TL;DR: The design rationale, novel kinematics and mechanics of the PHANToM, a device which measures a user’s finger tip position and exerts a precisely controlled force vector on the finger tip, are discussed.
Abstract: 1. Abstract This paper describes the PHANToM haptic interface - a device which measures a user’s finger tip position and exerts a precisely controlled force vector on the finger tip. The device has enabled users to interact with and feel a wide variety of virtual objects and will be used for control of remote manipulators. This paper discusses the design rationale, novel kinematics and mechanics of the PHANToM. A brief description of the programming of basic shape elements and contact interactions is also given.
01 Sep 1999
TL;DR: An algorithm is presented that minimizes the bias inherent in making measurements with a fixed set of gradient vector directions by spreading out measurements in 3‐dimensional gradient vector space and this results in reduced scan times, increased precision, or improved resolution in diffusion tensor images.
Abstract: The optimization of acquisition parameters for precise measurement of diffusion in anisotropic systems is described. First, an algorithm is presented that minimizes the bias inherent in making measurements with a fixed set of gradient vector directions by spreading out measurements in 3-dimensional gradient vector space. Next, it is shown how the set of b—matrices and echo time can be optimized for estimating the diffusion tensor and its scalar invariants. The standard deviation in the estimate of the tensor trace in a water phantom was reduced by more than 40% and the artefactual anisotropy was reduced by more than 60% when using the optimized scheme compared with a more conventional scheme for the same scan time, and marked improvements are demonstrated in the human brain with the optimized sequences. Use of these optimal schemes results in reduced scan times, increased precision, or improved resolution in diffusion tensor images. Magn Reson Med 42:515‐ 525, 1999. r 1999 Wiley-Liss, Inc.
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