Download or read book Electron Trajectory Reconstruction for Advanced Compton Imaging of Gamma Rays written by Brian Christopher Plimley and published by . This book was released on 2014 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gamma-ray imaging is useful for detecting, characterizing, and localizing sources in a variety of fields, including nuclear physics, security, nuclear accident response, nuclear medicine, and astronomy. Compton imaging in particular provides sensitivity to weak sources and good angular resolution in a large field of view. However, the photon origin in a single event sequence is normally only limited to the surface of a cone. If the initial direction of the Compton-scattered electron can be measured, the cone can be reduced to a cone segment with width depending on the uncertainty in the direction measurement, providing a corresponding increase in imaging sensitivity. Measurement of the electron's initial direction in an efficient detection material requires very fine position resolution due to the electron's short range and tortuous path. A thick (650 [mu]m), fully-depleted charge-coupled device (CCD) developed for infrared astronomy has 10.5-[mu]m position resolution in two dimensions, enabling the initial trajectory measurement of electrons of energy as low as 100 keV. This is the first time the initial trajectories of electrons of such low energies have been measured in a solid material. In this work, the CCD's efficacy as a gamma-ray detector is demonstrated experimentally, using a reconstruction algorithm to measure the initial electron direction from the CCD track image. In addition, models of fast electron interaction physics, charge transport and readout were used to generate modeled tracks with known initial direction. These modeled tracks allowed the development and refinement of the reconstruction algorithm. The angular sensitivity of the reconstruction algorithm is evaluated extensively with models for tracks below 480 keV, showing a FWHM as low as 20° in the pixel plane, and 30° RMS sensitivity to the magnitude of the out-of-plane angle. The measurement of the trajectories of electrons with energies as low as 100 keV have the potential to make electron track Compton imaging an effective means of reducing image background for photons of energy as low as 500 keV, or even less. The angular sensitivity of the reconstruction algorithm was also evaluated experimentally, by measuring electron tracks in the CCD in coincidence with the scattered photon in a germanium double-sided strip detector. By this method, electron tracks could be measured with the true initial direction known to within 3° FWHM, and the angular response of the algorithm compared to the known direction. The challenge of this experiment lay in the low geometric efficiency for photons scattering into the germanium, the poor time resolution in the current CCD implementation, and the resulting signal-to-background ratio of about 10−4 for photons scattered from the CCD into the germanium detector. Nonetheless, 87 events were measured in the FWHM of the total energy deposited and the angular resolution measure, with electron tracks between 160 keV and 360 keV in energy. The electron tracks from true coincident event sequences showed a FWHM in the pixel plane of 23°, and excellent agreement with the distribution calculated with models, with likelihood p-values of 0.44 and 0.73. Thus, the models used for the more thorough evaluation of angular sensitivities are shown to be consistent with the measured tracks from true coincident event sequences.
Download or read book Gamma ray Detection and Compton Camera Image Reconstruction with Application to Hadron Therapy written by Mirela Frandes and published by . This book was released on 2010 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel technique for radiotherapy - hadron therapy - irradiates tumors using a beam of protons or carbon ions. Hadron therapy is an effective technique for cancer treatment, since it enables accurate dose deposition due to the existence of a Bragg peak at the end of particles range. Precise knowledge of the fall-off position of the dose with millimeters accuracy is critical since hadron therapy proved its efficiency in case of tumors which are deep-seated, close to vital organs, or radio-resistant. A major challenge for hadron therapy is the quality assurance of dose delivery during irradiation. Current systems applying positron emission tomography (PET) technologies exploit gamma rays from the annihilation of positrons emitted during the beta decay of radioactive isotopes. However, the generated PET images allow only post-therapy information about the deposed dose. In addition, they are not in direct coincidence with the Bragg peak. A solution is to image the complete spectrum of the emitted gamma rays, including nuclear gamma rays emitted by inelastic interactions of hadrons to generated nuclei. This emission is isotropic, and has a spectrum ranging from 100 keV up to 20 MeV. However, the measurement of these energetic gamma rays from nuclear reactions exceeds the capability of all existing medical imaging systems. An advanced Compton scattering detection method with electron tracking capability is proposed, and modeled to reconstruct the high-energy gamma-ray events. This Compton detection technique was initially developed to observe gamma rays for astrophysical purposes. A device illustrating the method was designed and adapted to Hadron Therapy Imaging (HTI). It consists of two main sub-systems: a tracker where Compton recoiled electrons are measured, and a calorimeter where the scattered gamma rays are absorbed via the photoelectric effect. Considering a hadron therapy scenario, the analysis of generated data was performed, passing trough the complete detection chain from Monte Carlo simulations to reconstruction of individual events, and finally to image reconstruction. A list-mode Maximum-Likelihood Expectation-Maximization (MLEM) algorithm was adopted to perform image reconstruction in conjunction with the imaging response, which has to depict the complex behavior of the detector. Modeling the imaging response requires complex calculations, considering the incident angle, all measured energies, the Compton scatter angle in the first interaction, the direction of scattered electron (when measured). In the simplest form, each event response is described by Compton cone profiles. The shapes of the profiles are approximated by 1D Gaussian distributions. A strong correlation was observed between pattern of the reconstructed high-energy gamma events, and location of the Bragg peak. The performance of the imaging technique illustrated by the HTI is a function of the detector performance in terms of detection efficiency, spatial and energy resolution, acquisition time, and the algorithms used to reconstruct the gamma-ray activity. Thus beside optimizations of the imaging system, the applied imaging algorithm has a high influence on the final reconstructed images. The HTI reconstructed images are corrupted by noise due to the low photon counts recorded, the uncertainties induced by finite energy resolution, Doppler broadening, the limited model used to estimate the imaging response, and the artifacts generated when iterating the MLEM algorithm. This noise is spatially varying and signal-dependent, representing a major obstacle for information extraction. Thus image de-noising techniques were investigated. AWavelet based multi-resolution strategy of list-mode MLEMRegularization (WREM) was developed to reconstruct Compton images. At each iteration, a threshold-based processing step was integrated. The noise variance was estimated at each scale of the wavelet decomposition as the median value of the coefficients from the high-frequency sub-bands. This approach allowed to obtain a stable behavior of the iterative algorithm, presenting lower mean-squared error, and improved contrast recovery ratio.
Download or read book Gamma ray Momentum Reconstruction from Compton Electron Trajectories by Filtered Back projection written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Gamma-ray imaging utilizing Compton scattering has traditionally relied on measuring coincident gamma-ray interactions to map directional information of the source distribution. This coincidence requirement makes it an inherently inefficient process. We present an approach to gamma-ray reconstruction from Compton scattering that requires only a single electron tracking detector, thus removing the coincidence requirement. From the Compton scattered electron momentum distribution, our algorithm analytically computes the incident photon's correlated direction and energy distributions. Because this method maps the source energy and location, it is useful in applications, where prior information about the source distribution is unknown. We demonstrate this method with electron tracks measured in a scientific Si charge coupled device. While this method was demonstrated with electron tracks in a Si-based detector, it is applicable to any detector that can measure electron direction and energy, or equivalently the electron momentum. For example, it can increase the sensitivity to obtain energy and direction in gas-based systems that suffer from limited efficiency.
Download or read book Gamma Ray Imaging written by Junwei Du and published by Springer Nature. This book was released on 2023-09-12 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will provide readers with a good overview of some of the most recent advances in the field of detector technology for gamma-ray imaging, especially as it pertains to new applications. There will be a good mixture of general chapters in both technology and applications in medical imaging and industrial testing. The book will have an in-depth review of the research topics from world-leading specialists in the field. The conversion of the gamma-ray signal into analog/digital value will be covered in some chapters. Some would also provide a review of CMOS chips for gamma-ray image sensors.
Download or read book Handbook of X ray and Gamma ray Astrophysics written by Cosimo Bambi and published by Springer Nature. This book was released on with total page 5912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book written by and published by . This book was released on 1957 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Compton Scatter Camera for Spectral Imaging of 0 5 to 3 0 MeV Gamma Rays written by Jeffrey Basil Martin and published by . This book was released on 1994 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Evaluation of Gamma Imaging Systems of Compton and Hybrid Cameras written by Yuxin Feng and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For medical applications in proton therapy, a Compton camera system to image the gamma-ray emission during treatment was designed and investigated. Gamma rays and X-rays emitted during treatment illustrate the energy deposition along the path of the proton beams and provide an opportunity for online dose verification. This Compton camera is designed to be capable of imaging gamma rays in 3D and is one of the candidates for imaging gamma emission during the treatment of proton therapy beside of the approach of positron emission tomography. In order to meet the requirement for spatial resolution of approximately 5 mm or less to meaningfully verify the dose via imaging gamma rays of 511 keV to 2 MeV, position sensing techniques with pixilated LaBr3(Ce) crystal were applied in each detector. The pixilated LaBr3 (Ce) crystal was used in both the scattering and absorbing detectors. Image reconstruction algorithms of OS-EML were applied to obtain 3D images.
Download or read book Gamma Ray Backscatter Imaging written by Gavin Wallace and published by . This book was released on 2006 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Methods for Tomographic Reconstruction in Gamma and X ray Imaging written by Tobias Lasser and published by . This book was released on 2017* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Practical Gamma ray Spectrometry written by Gordon Gilmore and published by John Wiley & Sons. This book was released on 2024-09-04 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cutting-edge new edition of the classic introduction to radioactive measurement Gammy-Ray Spectrometry is a key technique in the study of radioactive decay. It measures the rate and extent of radioactivity from a variety of sources, both natural and artificial, including cosmic ray sources, nuclear reactors, high-energy physics experiments, and more. The resulting data can be essential to environmental monitoring and to a range of experimental sciences. For years, Practical Gamma-Ray Spectrometry has served as the classic introduction to this area for current or aspiring practitioners. A comprehensive but accessible treatment of the subject, with a thorough discussion of all major classes of detectors and their associated electronic systems, it contains everything a researcher needs to make optimal gamma-ray measurements. Now fully updated to reflect the latest technology and experimental data, it is a must-own for researchers looking to incorporate gamma-ray spectrometry into their scientific practice. Readers of the third edition of Practical Gamma-Ray Spectrometry will also find: Fault-finding guide for rapid and effective problem resolution Workshop-style approach emphasizing the fundamentals of laboratory practice New sections dealing with novel developments in nuclear structure research, measuring effects of pollution and climate change, new semiconductor detectors, and more Practical Gamma-Ray Spectrometry is ideal for PhD students and practicing gamma-ray spectroscopists, including researchers working on radiation, energy and environmental monitoring professionals, and researchers working in physics, archaeometry, and related subjects.
Download or read book Medical Imaging Systems written by Andreas Maier and published by Springer. This book was released on 2018-08-02 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book gives a complete and comprehensive introduction to the fields of medical imaging systems, as designed for a broad range of applications. The authors of the book first explain the foundations of system theory and image processing, before highlighting several modalities in a dedicated chapter. The initial focus is on modalities that are closely related to traditional camera systems such as endoscopy and microscopy. This is followed by more complex image formation processes: magnetic resonance imaging, X-ray projection imaging, computed tomography, X-ray phase-contrast imaging, nuclear imaging, ultrasound, and optical coherence tomography.
Download or read book Emission Tomography written by Miles N. Wernick and published by Elsevier. This book was released on 2004-12-07 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: PET and SPECT are two of today's most important medical-imaging methods, providing images that reveal subtle information about physiological processes in humans and animals. Emission Tomography: The Fundamentals of PET and SPECT explains the physics and engineering principles of these important functional-imaging methods. The technology of emission tomography is covered in detail, including historical origins, scientific and mathematical foundations, imaging systems and their components, image reconstruction and analysis, simulation techniques, and clinical and laboratory applications. The book describes the state of the art of emission tomography, including all facets of conventional SPECT and PET, as well as contemporary topics such as iterative image reconstruction, small-animal imaging, and PET/CT systems. This book is intended as a textbook and reference resource for graduate students, researchers, medical physicists, biomedical engineers, and professional engineers and physicists in the medical-imaging industry. Thorough tutorials of fundamental and advanced topics are presented by dozens of the leading researchers in PET and SPECT. SPECT has long been a mainstay of clinical imaging, and PET is now one of the world's fastest growing medical imaging techniques, owing to its dramatic contributions to cancer imaging and other applications. Emission Tomography: The Fundamentals of PET and SPECT is an essential resource for understanding the technology of SPECT and PET, the most widely used forms of molecular imaging.*Contains thorough tutorial treatments, coupled with coverage of advanced topics*Three of the four holders of the prestigious Institute of Electrical and Electronics Engineers Medical Imaging Scientist Award are chapter contributors*Include color artwork
Download or read book Industrial Process Gamma Tomography written by International Atomic Energy Agency and published by . This book was released on 2008 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book World Congress on Medical Physics and Biomedical Engineering May 26 31 2012 Beijing China written by Mian Long and published by Springer Science & Business Media. This book was released on 2013-02-11 with total page 2385 pages. Available in PDF, EPUB and Kindle. Book excerpt: The congress’s unique structure represents the two dimensions of technology and medicine: 13 themes on science and medical technologies intersect with five challenging main topics of medicine to create a maximum of synergy and integration of aspects on research, development and application. Each of the congress themes was chaired by two leading experts. The themes address specific topics of medicine and technology that provide multiple and excellent opportunities for exchanges.
Download or read book Mathematics and Physics of Emerging Biomedical Imaging written by Committee on the Mathematics and Physics of Emerging Dynamic Biomedical Imaging and published by National Academies Press. This book was released on 1996-03-13 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: This cross-disciplinary book documents the key research challenges in the mathematical sciences and physics that could enable the economical development of novel biomedical imaging devices. It is hoped that the infusion of new insights from mathematical scientists and physicists will accelerate progress in imaging. Incorporating input from dozens of biomedical researchers who described what they perceived as key open problems of imaging that are amenable to attack by mathematical scientists and physicists, this book introduces the frontiers of biomedical imaging, especially the imaging of dynamic physiological functions, to the educated nonspecialist. Ten imaging modalities are covered, from the well-established (e.g., CAT scanning, MRI) to the more speculative (e.g., electrical and magnetic source imaging). For each modality, mathematics and physics research challenges are identified and a short list of suggested reading offered. Two additional chapters offer visions of the next generation of surgical and interventional techniques and of image processing. A final chapter provides an overview of mathematical issues that cut across the various modalities.
Download or read book Remote Compositional Analysis written by Janice L. Bishop and published by Cambridge University Press. This book was released on 2019-11-28 with total page 655 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive overview of the spectroscopic, mineralogical, and geochemical techniques used in planetary remote sensing.
