Topic
Imaging phantom
About: Imaging phantom is a research topic. Over the lifetime, 28170 publications have been published within this topic receiving 510003 citations. The topic is also known as: phantom.
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TL;DR: In this paper, the authors discuss a class of phantom cosmological models and discuss the problem of singularities for these cosmologies, and find an interesting relation between the phantom models and standard matter models which is like the duality symmetry of string cosmology.
Abstract: We discuss a class of phantom ($p < - \varrho$) cosmological models Except for phantom we admit various forms of standard types of matter and discuss the problem of singularities for these cosmologies The singularities are different from those of standard matter cosmology since they appear for infinite values of the scale factor We also find an interesting relation between the phantom models and standard matter models which is like the duality symmetry of string cosmology
273 citations
Book•
12 Dec 2002
TL;DR: This paper presents the general principles of Imaging with X-Rays and Computed Tomography, and some of the techniques used in this work, as well as some of its applications, which include clinical applications of Nuclear Medicine and MRI.
Abstract: Preface. Acknowledgments. 1. X-Ray Imaging and Computed Tomography. 1.1 General Principles of Imaging with X-Rays. 1.2 X-Ray Production. 1.3 Interactions of X-Rays with Tissue. 1.4 Linear and Mass Attenuation Coefficients of X-Rays in Tissue. 1.5 Instrumentation for Planar X-Ray Imaging. 1.6 X-Ray Image Characteristics. 1.7 X-Ray Contrast Agents. 1.8 X-Ray Imaging Methods. 1.9 Clinical Applications of X-Ray Imaging. 1.10 Computed Tomography. 1.11 Image Processing for Computed Tomography. 1.12 Spiral/Helical Computed Tomography. 1.13 Multislice Spiral Computed Tomography. 1.14 Radiation Dose. 1.15 Clinical Applications of Computed Tomography. 2. Nuclear Medicine. 2.1 General Principles of Nuclear Medicine. 2.2 Radioactivity. 2.3 The Production of Radionuclides. 2.4 Types of Radioactive Decay. 2.5 The Technetium Generator. 2.6 The Biodistribution of Technetium-Based Agents within the Body. 2.7 Instrumentation: The Gamma Camera. 2.8 Image Characteristics. 2.9 Single Photon Emission Computed Tomography. 2.10 Clinical Applications of Nuclear Medicine. 2.11 Positron Emission Tomography. 3. Ultrasonic Imaging. 3.1 General Principles of Ultrasonic Imaging. 3.2 Wave Propagation and Characteristic Acoustic Impedance. 3.3 Wave Reflection and Refraction. 3.4 Energy Loss Mechanisms in Tissue. 3.5 Instrumentation. 3.6 Diagnostic Scanning Modes. 3.7 Artifacts in Ultrasonic Imaging. 3.8 Image Characteristics. 3.9 Compound Imaging. 3.10 Blood Velocity Measurements Using Ultrasound. 3.11 Ultrasound Contrast Agents, Harmonic Imaging, and Pulse Inversion Techniques. 3.12 Safety and Bioeffects in Ultrasonic Imaging. 3.13 Clinical Applications of Ultrasound. 4. Magnetic Resonance Imaging. 4.1 General Principles of Magnetic Resonance Imaging. 4.2 Nuclear Magnetism. 4.3 Magnetic Resonance Imaging. 4.4 Instrumentation. 4.5 Imaging Sequences. 4.6 Image Characteristics. 4.7 MRI Contrast Agents. 4.8 Magnetic Resonance Angiography. 4.9 Diffusion-Weighted Imaging. 4.10 In Vivo Localized Spectroscopy. 4.11 Functional MRI. 4.12 Clinical Applications of MRI. 5. General Image Characteristics. 5.1 Introduction. 5.2 Spatial Resolution. 5.3 Signal-to-Noise Ratio. 5.4 Contrast-to-Noise Ratio. 5.5 Image Filtering. 5.6 The Receiver Operating Curve. Appendix A: The Fourier Transform. Appendix B: Backprojection and Filtered Backprojection. Abbreviations. Index.
272 citations
TL;DR: The application of 3D radial sampling of the free‐induction decay to proton ultrashort echo‐time (UTE) imaging is reported and a maximal signal‐to‐noise ratio (SNR) with negligible decay‐induced loss in spatial resolution is obtained.
Abstract: The application of 3D radial sampling of the free-induction decay to proton ultrashort echo-time (UTE) imaging is reported. The effects of T2 decay during signal acquisition on the 3D radial point-spread function are analyzed and compared to 2D radial and 1D sampling. It is found that in addition to the use of ultrashort TE, the proper choice of the acquisition-window duration TAQ is essential for imaging short-T2 components. For 3D radial sampling, a maximal signal-to-noise ratio (SNR) with negligible decay-induced loss in spatial resolution is obtained for an acquisition-window duration of TAQ ≈ 0.69 T2. For 2D and 1D sampling, corresponding values are derived as well. Phantom measurements confirm the theoretical findings and demonstrate the impact of different acquisition-window durations on SNR and spatial resolution for a given T2 component. In vivo scans show the potential of 3D UTE imaging with T2-adapted sampling for musculoskeletal imaging using standard MR equipment. The visualization of complex anatomy is demonstrated by extracting curved slices from the isotropically resolved 3D UTE image data. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc.
271 citations
TL;DR: This work demonstrates the feasibility of nonlinear harmonic imaging in medical scanners using a simple broadband imaging arrangement in water using a 2.25-MHz circular transducer, membrane hydrophone, and polymer lens with a focal length of 262 mm.
Abstract: Medical B-mode scanners operating under conditions typically encountered during clinical work produce ultrasonic wave fields that undergo nonlinear distortion. In general, the resulting harmonic beams are narrower and have lower sidelobe levels than the fundamental beam, making them ideal for imaging purposes. This work demonstrates the feasibility of nonlinear harmonic imaging in medical scanners using a simple broadband imaging arrangement in water. The ultrasonic system comprises a 2.25-MHz circular transducer with a diameter of 38 mm, a membrane hydrophone, also with a diameter of 38 mm, and a polymer lens with a focal length of 262 mm. These components are arranged coaxially giving an imaging geometry similar to that used in many commercial B-scanners, but with a receiver bandwidth sufficient to record the first four harmonics. A series of continuous wave and pulse-echo measurements are performed on a wire phantom to give 1-D transverse pressure profiles and 2-D B-mode images, respectively. The refle...
270 citations
TL;DR: Combining the transducers array and IC allows for better utilization of large arrays, improves receive sensitivity, and may lead to new imaging techniques that depend on transducer arrays that are closely coupled to IC electronics.
Abstract: For three-dimensional (3D) ultrasound imaging, connecting elements of a two-dimensional (2D) transducer array to the imaging system's front-end electronics is a challenge because of the large number of array elements and the small element size. To compactly connect the transducer array with electronics, we flip-chip bond a 2D 16 times 16-element capacitive micromachined ultrasonic transducer (CMUT) array to a custom-designed integrated circuit (IC). Through-wafer interconnects are used to connect the CMUT elements on the top side of the array with flip-chip bond pads on the back side. The IC provides a 25-V pulser and a transimpedance preamplifier to each element of the array. For each of three characterized devices, the element yield is excellent (99 to 100% of the elements are functional). Center frequencies range from 2.6 MHz to 5.1 MHz. For pulse-echo operation, the average -6-dB fractional bandwidth is as high as 125%. Transmit pressures normalized to the face of the transducer are as high as 339 kPa and input-referred receiver noise is typically 1.2 to 2.1 rnPa/ radicHz. The flip-chip bonded devices were used to acquire 3D synthetic aperture images of a wire-target phantom. Combining the transducer array and IC, as shown in this paper, allows for better utilization of large arrays, improves receive sensitivity, and may lead to new imaging techniques that depend on transducer arrays that are closely coupled to IC electronics.
270 citations