scholarly journals Compton imaging with 99mTc for human imaging

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Makoto Sakai ◽  
Yoshiki Kubota ◽  
Raj Kumar Parajuli ◽  
Mikiko Kikuchi ◽  
Kazuo Arakawa ◽  
...  
Keyword(s):  
Imaging System ◽  
Experimental Studies ◽  
Region Of Interest ◽  
Simulation Studies ◽  
Compton Camera ◽  
Compton Imaging ◽  
Cdte Detector ◽  
Prior Expectation ◽  
Probability Of Success ◽  
Activity Ratios

Abstract We have been developing a medical imaging system using a Compton camera and demonstrated the imaging ability of Compton camera for 99mTc-DMSA accumulated in rat kidneys. In this study, we performed imaging experiments using a human body phantom to confirm its applicability to human imaging. Preliminary simulations were conducted using a digital phantom with varying activity ratios between the kidney and body trunk regions. Gamma rays (141 keV) were generated and detected by a Compton camera based on a silicon and cadmium telluride (Si/CdTe) detector. Compton images were reconstructed with the list mode median root prior expectation maximization method. The appropriate number of iterations of the condition was confirmed through simulations. The reconstructed Compton images revealed two bright points in the kidney regions. Furthermore, the numerical value calculated by integrating pixel values inside the region of interest correlated well with the activity of the kidney regions. Finally, experimental studies were conducted to ascertain whether the results of the simulation studies could be reproduced. The kidneys could be successfully visualised. In conclusion, considering that the conditions in this study agree with those of typical human bodies and imaginable experimental setup, the Si/CdTe Compton camera has a high probability of success in human imaging. In addition, our results indicate the capability of (semi-) quantitative analysis using Compton images.

scholarly journals Frequency-Diverse Holographic Metasurface Antenna for Near-Field Microwave Computational Imaging

2021 ◽  
Vol 8 ◽  
Author(s):  
Jiaqi Han ◽  
Long Li ◽  
Shuncheng Tian ◽  
Xiangjin Ma ◽  
Qiang Feng ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Imaging System ◽  
Near Field ◽  
Horn Antenna ◽  
Computational Imaging ◽  
Simulation Studies ◽  
Field Patterns ◽  
Full Wave ◽  
Imaging Reconstruction ◽  
Iterative Shrinkage

This article presents a holographic metasurface antenna with stochastically distributed surface impedance, which produces randomly frequency-diverse radiation patterns. Low mutual coherence electric field patterns generated by the holographic metasurface antenna can cover the K-band from 18 to 26 GHz with 0.1 GHz intervals. By utilizing the frequency-diverse holographic metasurface (FDHM) antenna, we build a near-field microwave computational imaging system based on reflected signals in the frequency domain. A standard horn antenna is adopted to acquire frequency domain signals radiated from the proposed FDHM antenna. A detail imaging restoration process is presented, and the desired targets are correctly reconstructed using the 81 frequency-diverse patterns through full-wave simulation studies. Compressed sensing technique and iterative shrinkage/thresholding algorithms are applied for the imaging reconstruction. The achieved compressive ratio of this computational imaging system on the physical layer is 30:1.

Development of electron-tracking Compton imaging system with 30-μm SOI pixel sensor

2017 ◽  
Vol 12 (01) ◽  
pp. C01045-C01045 ◽  
Author(s):  
Y. Yoshihara ◽  
K. Shimazoe ◽  
Y. Mizumachi ◽  
H. Takahashi ◽  
K. Kamada ◽  
...  
Keyword(s):  
Imaging System ◽  
Compton Imaging

Acoustic Speckle: Theory and Experimental Analysis

1979 ◽  
Vol 1 (4) ◽  
pp. 303-324 ◽  
Author(s):  
John G. Abbott ◽  
F. L. Thurstone
Keyword(s):  
Experimental Study ◽  
Experimental Analysis ◽  
Phased Array ◽  
Imaging System ◽  
Experimental Studies ◽  
Laser Speckle ◽  
Speckle Reduction ◽  
Multiple Images ◽  
Starting Point ◽  
Speckle Patterns

A theoretical and experimental study of speckle, as applied to ultrasonic imaging, is presented. The concept of laser speckle is briefly reviewed and is used as a starting point to explain the origin of acoustic speckle. The primary differences between these two phenomena are discussed and are confirmed by experiment. An experimental study of speckle reduction by summation of multiple images is also presented. Several techniques for generating independent speckle patterns for use in image summation schemes are proposed. A phased array, dynamically focused sector imaging system was used in all of the experimental studies reported.

scholarly journals Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

2021 ◽  
Author(s):  
Kaveh Dargahi Noubary ◽  
Michael Kellner ◽  
Johannes Hötzer ◽  
Marco Seiz ◽  
Hans J. Seifert ◽  
...  
Keyword(s):  
Gibbs Energy ◽  
Phase Field ◽  
Ternary Eutectic ◽  
Experimental Studies ◽  
Simulation Studies ◽  
Grand Potential ◽  
Material Systems ◽  
Temperature Ranges ◽  
Equilibrium Concentrations ◽  
Direct Generation

Abstract In order to approximate Gibbs energy functions, a semi-automated framework is introduced for binary and ternary material systems, using Calphad databases. To generate Gibbs energy formulations by means of second-order polynomials, the framework includes a precise approach. Furthermore, an optional extensional step enables the modeling of systems in which a direct generation leads to the unsatisfactory results in the representation of the thermodynamics. Furthermore, an optional extensional step enables the modeling of systems, in which a direct generation leads to the unsatisfactory results, when representing the thermodynamics. Within this extension, the commonly generated functions are modified to satisfy the equilibrium conditions in the observed material systems, leading to a better correlation with thermodynamic databases. The generated Gibbs energy formulations are verified by recalculating the equilibrium concentrations of the phases and rebuilding the phase diagrams in the considered concentration and temperature ranges, prior to the simulation studies. For all comparisons, a close match is achieved between the results and the Calphad databases. As practical examples of the method, phase-field simulation studies for the directional solidification of the binary – and the ternary – eutectic systems are performed. Good agreements between the simulation results and the reported theoretical and experimental studies from literature are found, which indicates the applicability of the presented approaches. Graphical Abstract

scholarly journals Intramyocellular Lipid Changes in Men and Women during Aerobic Exercise: A 1H-Magnetic Resonance Spectroscopy Study

2003 ◽  
Vol 88 (12) ◽  
pp. 5638-5643 ◽  
Author(s):  
Lesley J. White ◽  
Michael A. Ferguson ◽  
Sean C. McCoy ◽  
HeeWon Kim
Keyword(s):  
Body Composition ◽  
Imaging System ◽  
Vastus Lateralis ◽  
Region Of Interest ◽  
Whole Body ◽  
Resonance Spectroscopy ◽  
Whole Body Imaging ◽  
Intramyocellular Lipid ◽  
Men And Women ◽  
Magnetic Resonance Spectroscopy Study

Abstract This study was designed to compare intramyocellular lipid (IMCL) changes during 60 min of submaximal exercise in men and women. Eighteen moderately active (18–38 yr) men (n = 9) and women (n = 9) were recruited. Maximum oxygen consumption (V̇O2max) and body composition were used to match subjects for aerobic fitness and body composition. Subjects performed cycle ergometry for 1 h at 65% of V̇O2max. Expired gases were collected throughout exercise to determine caloric expenditure and substrate use. Blood samples were collected before and after exercise to evaluate markers of lipid metabolism. Pre- and postexercise proton spectra were acquired from the vastus lateralis using a 3-T whole-body imaging system. Spectra were acquired from an 18-mm3 region of interest (echo time = 45 msec; repetition time = 2000 msec) for IMCL evaluation. IMCL decreased significantly with exercise (11.5–28.5% for men and 17.1–21.7% for women) (P < 0.05); however, there were no significant differences between men and women. Although changes were found for many plasma variables [free fatty acids, glycerol, and norepinephrine (P < 0.05)], group differences were only evident for norepinephrine. In conclusion, a significant decrease in IMCL was observed during 60 min of cycling in matched men and women.

scholarly journals Imaging of Conductivity Changes of Excitable Tissues Based on Focused Passive Microwave

2015 ◽  
Vol 9 (1) ◽  
pp. 138-145 ◽  
Author(s):  
Irene Karanasiou
Keyword(s):  
Functional Organization ◽  
Imaging System ◽  
Experimental Studies ◽  
Human Head ◽  
Black Body Radiation ◽  
Human Volunteer ◽  
Microwave Radiometry ◽  
Spatial Average ◽  
Ellipsoidal Cavity ◽  
Detection Depth

Aims:Modeling of ionic distribution fluctuations of excitable tissues based on data elicited using focused microwave radiometry.Methodology:Focused Microwave Radiometry implemented to carry out measurements of in depth body temperature distributions, may provide the capability of sensing local electrical conductivity fluctuations during the cycle of actions potentials in the case of brain excitable cell clusters. An analog beamformer consisting of a conductive inner-surface ellipsoidal cavity is used to focus the chaotic-black body radiation emerging from human tissues by providing convergence of the electromagnetic energy from one focus area where the phantom or subject is placed, to the other where the antennas of sensitive radiometric receivers are positioned. During the past 10 years numerous phantom, animal and human volunteer experiments have been performed with the focused radiometry imaging system. The results show that the detected changes of the output radiometric voltage are attributed to temperature and/or conductivity changes that occur locally concentrated at the areas of interest under measurement. Theoretical and experimental studies are continuously carried out at various frequency bands in conjunction with the use of matching materials placed around the human head or phantom to improve focusing and detection depth. It seems that the manipulation of the focusing area in the tissue in terms of detection depth and spatial resolution is feasible depending on the suitable combination of operation frequencies and matching material. In this paper, theoretical analysis of ion charge diffusion during the cycle of action potentials, propagating along the axons in case of measurements of specific cortical regions is presented. The ion charge diffusion modeling is based on electromagnetic diffusion analogies in the effort to explain the observed experimental results obtained under various psychophysiological conditions in the case of human volunteer measurements.Results:By implementing an analysis based on the continuity equations of ionic charges it is concluded that the microwave radiometry output voltage is not affected by the temporal and spatial average fluctuations of Na+, K+, and Cl-ions of neural cell axons.Conclusion:The analysis of conductivity fluctuations in the central neural system in conjunction with the electromagnetic analysis of the system, leads to the interpretation of the previously acquired experimental data. The application of this technique with other brain functional mapping methods, may provide complementary knowledge to the understanding of the functional organization of psychophysiological processes.

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