James Hugg - Academia.edu (original) (raw)

Papers by James Hugg

The Journal of Nuclear Medicine, 2012

The embodiments relate to an imaging system (10) comprising a collimator (12) having one or more ... more The embodiments relate to an imaging system (10) comprising a collimator (12) having one or more openings formed therein (40). The imaging system (10) further comprises a detector arrangement (14) which is configured so that in response to gamma rays (30) pass through the one or more openings (40), one or more signals are generated. The imaging system (10) is configured so that at least one of the one or more via openings (40) has an adjustable focal length. The embodiments also relate to methods for changing the Kollimatorleistung and method for imaging a volume.

M. J. Hamamura, H. J. Yu, S. Ha, W. W. Roeck, J. W. Hugg, D. J. Wagenaar, D. Meier, B. E. Patt, a... more M. J. Hamamura, H. J. Yu, S. Ha, W. W. Roeck, J. W. Hugg, D. J. Wagenaar, D. Meier, B. E. Patt, and O. Nalcioglu Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, CA, United States, Gamma Medica, Inc. (Clinical Division), Northridge, CA, United States, Gamma Medica, Inc. (Industrial Division), Fornebu, Norway, Department of Cogno-Mechatronics Engineering, Pusan National University, Pusan, Republic of Korea

The Journal of Nuclear Medicine, 2013

Medical Imaging 2017: Physics of Medical Imaging

PURPOSE Pixelated CdZnTe (CZT) detector arrays are used in molecular imaging applications that ca... more PURPOSE Pixelated CdZnTe (CZT) detector arrays are used in molecular imaging applications that can enable precision medicine, including small-animal SPECT, cardiac SPECT, molecular breast imaging (MBI), and general purpose SPECT. The interplay of gamma camera, collimator, gantry motion, and image reconstruction determines image quality and dose-time-FOV tradeoffs. Both dose and exam time can be minimized without compromising diagnostic content. METHODS Integration of pixelated CZT detectors with advanced ASICs and readout electronics improves system performance. Because historically CZT was expensive, the first clinical applications were limited to small FOV. Radiation doses were initially high and exam times long. Advances have significantly improved efficiency of CZT-based molecular imaging systems and the cost has steadily declined. We have built a general purpose SPECT system using our 40 cm x 53 cm CZT gamma camera with 2 mm pixel pitch and characterized system performance. RESULTS Compared to NaI scintillator gamma cameras: intrinsic spatial resolution improved from 3.8 mm to 2.0 mm; energy resolution improved from 9.8% to <4 % at 140 keV; maximum count rate is <1.5 times higher; non-detection camera edges are reduced ~3-fold. Scattered photons are greatly reduced in the photopeak energy window; image contrast is improved; and the optimal FOV is increased to the entire camera area. CONCLUSION Continual improvements in CZT detector arrays for molecular imaging, coupled with optimal collimator and image reconstruction, result in minimized dose and exam time. With CZT cost improving, affordable whole-body CZT general purpose SPECT is expected to enable precision medicine applications.

Radiolabeled cells have been imaged for decades in the field of autoradiography. Recent advances ... more Radiolabeled cells have been imaged for decades in the field of autoradiography. Recent advances in detector and microelectronics technologies have enabled the new field of "digital autoradiography" which remains limited to ex vivo specimens of thin tissue slices. The 3D field-of-view (FOV) of single cell imaging can be extended to millimeters if the low energy (10-30 keV) photon emissions of radionuclides are used for single-photon nuclear imaging. This new microscope uses a coded aperture foil made of highly attenuating elements such as gold or platinum to form the image as a kind of "lens". The detectors used for single-photon emission microscopy are typically silicon detectors with a pixel pitch less than 60 mum. The goal of this work is to image radiolabeled mesenchymal stem cells in vivo in an animal model of tendon repair processes. Single-photon nuclear imaging is an attractive modality for translational medicine since the labeled cells can be imaged simu...

Physics in Medicine and Biology, 2011

Despite its high sensitivity, the variable specificity of magnetic resonance imaging (MRI) in bre... more Despite its high sensitivity, the variable specificity of magnetic resonance imaging (MRI) in breast cancer diagnosis can lead to unnecessary biopsies and over-treatment. Scintimammography (SMM) could potentially supplement MRI to improve the diagnostic specificity. The synergistic combination of MRI and SMM (MRSMM) could result in both high sensitivity from MRI and high specificity from SMM. Development of such a dual-modality system requires the integration of a radio frequency (RF) coil and radiation detector in a strong magnetic field without significant mutual interference. In this study, we developed and tested a unilateral breast array coil specialized for MRSMM imaging. The electromagnetic field, specific absorption ratio and RF coil parameters with cadmium-zinc-telluride detectors encapsulated in specialized RF and gamma-ray shielding mounted within the RF coil were investigated through simulation and experimental measurements. Simultaneous MR and SMM images of a breast phantom were also acquired using the integrated MRSMM system. This work, we feel, represents an important step toward the fabrication of a working MRSMM system.

IEEE Transactions on Radiation and Plasma Medical Sciences

Improving 511 keV photon detection sensitivity is a common goal for positron emission tomography ... more Improving 511 keV photon detection sensitivity is a common goal for positron emission tomography system designers. One attractive approach to increase sensitivity is recovering events that are normally rejected. The kinematics of Compton scattering can be used to recover the line of response through direction difference angle (DDA). The uncertainty of DDA is determined by the energy and spatial resolution of a system. In this work, we evaluated the performance of small animal CZT-based positron emission tomography systems with energy resolution of 1%, 4%, and 6% and different spatial resolution based on prior work for guiding new design efforts. Designs with energy resolution limited by counting statistics and by electronic noise were considered. The influence of modifying the conventional energy window and uncertainty of DDA was investigated. For a system with 4% energy resolution and limited by electronic noise, the figure of merit of noise equivalent count increases by 65% as the lower energy bound increases from 471 keV to 493 keV. If the system-wide energy resolution becomes worse than 4% of the full width half maximum at 511 keV, going to a pixel size finer than 1 mm has very limited effect in reducing total angular uncertainty. For a system with 1% energy resolution, as the spatial resolution improves from 1 mm to 0.5 mm, the contrast-to-noise ratio increases by 9%.

AIP Conference Proceedings, 1981

AIP Conference Proceedings, 1976

A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used... more A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used as a polarized proton target. We measured a target density of 2×10&amp;amp;amp;amp;amp;amp;#39;&amp;amp;amp;amp;amp;amp;#39; atoms/cm3 and a target polarization of 0.37 without the use of r.f. transitions. These measurements indicate that a number of experiments are currently feasible with a variety of polarized target

AIP Conference Proceedings, 1981

The Journal of Nuclear Medicine, 2012

The embodiments relate to an imaging system (10) comprising a collimator (12) having one or more ... more The embodiments relate to an imaging system (10) comprising a collimator (12) having one or more openings formed therein (40). The imaging system (10) further comprises a detector arrangement (14) which is configured so that in response to gamma rays (30) pass through the one or more openings (40), one or more signals are generated. The imaging system (10) is configured so that at least one of the one or more via openings (40) has an adjustable focal length. The embodiments also relate to methods for changing the Kollimatorleistung and method for imaging a volume.

M. J. Hamamura, H. J. Yu, S. Ha, W. W. Roeck, J. W. Hugg, D. J. Wagenaar, D. Meier, B. E. Patt, a... more M. J. Hamamura, H. J. Yu, S. Ha, W. W. Roeck, J. W. Hugg, D. J. Wagenaar, D. Meier, B. E. Patt, and O. Nalcioglu Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, CA, United States, Gamma Medica, Inc. (Clinical Division), Northridge, CA, United States, Gamma Medica, Inc. (Industrial Division), Fornebu, Norway, Department of Cogno-Mechatronics Engineering, Pusan National University, Pusan, Republic of Korea

The Journal of Nuclear Medicine, 2013

Medical Imaging 2017: Physics of Medical Imaging

PURPOSE Pixelated CdZnTe (CZT) detector arrays are used in molecular imaging applications that ca... more PURPOSE Pixelated CdZnTe (CZT) detector arrays are used in molecular imaging applications that can enable precision medicine, including small-animal SPECT, cardiac SPECT, molecular breast imaging (MBI), and general purpose SPECT. The interplay of gamma camera, collimator, gantry motion, and image reconstruction determines image quality and dose-time-FOV tradeoffs. Both dose and exam time can be minimized without compromising diagnostic content. METHODS Integration of pixelated CZT detectors with advanced ASICs and readout electronics improves system performance. Because historically CZT was expensive, the first clinical applications were limited to small FOV. Radiation doses were initially high and exam times long. Advances have significantly improved efficiency of CZT-based molecular imaging systems and the cost has steadily declined. We have built a general purpose SPECT system using our 40 cm x 53 cm CZT gamma camera with 2 mm pixel pitch and characterized system performance. RESULTS Compared to NaI scintillator gamma cameras: intrinsic spatial resolution improved from 3.8 mm to 2.0 mm; energy resolution improved from 9.8% to <4 % at 140 keV; maximum count rate is <1.5 times higher; non-detection camera edges are reduced ~3-fold. Scattered photons are greatly reduced in the photopeak energy window; image contrast is improved; and the optimal FOV is increased to the entire camera area. CONCLUSION Continual improvements in CZT detector arrays for molecular imaging, coupled with optimal collimator and image reconstruction, result in minimized dose and exam time. With CZT cost improving, affordable whole-body CZT general purpose SPECT is expected to enable precision medicine applications.

Radiolabeled cells have been imaged for decades in the field of autoradiography. Recent advances ... more Radiolabeled cells have been imaged for decades in the field of autoradiography. Recent advances in detector and microelectronics technologies have enabled the new field of "digital autoradiography" which remains limited to ex vivo specimens of thin tissue slices. The 3D field-of-view (FOV) of single cell imaging can be extended to millimeters if the low energy (10-30 keV) photon emissions of radionuclides are used for single-photon nuclear imaging. This new microscope uses a coded aperture foil made of highly attenuating elements such as gold or platinum to form the image as a kind of "lens". The detectors used for single-photon emission microscopy are typically silicon detectors with a pixel pitch less than 60 mum. The goal of this work is to image radiolabeled mesenchymal stem cells in vivo in an animal model of tendon repair processes. Single-photon nuclear imaging is an attractive modality for translational medicine since the labeled cells can be imaged simu...

Physics in Medicine and Biology, 2011

Despite its high sensitivity, the variable specificity of magnetic resonance imaging (MRI) in bre... more Despite its high sensitivity, the variable specificity of magnetic resonance imaging (MRI) in breast cancer diagnosis can lead to unnecessary biopsies and over-treatment. Scintimammography (SMM) could potentially supplement MRI to improve the diagnostic specificity. The synergistic combination of MRI and SMM (MRSMM) could result in both high sensitivity from MRI and high specificity from SMM. Development of such a dual-modality system requires the integration of a radio frequency (RF) coil and radiation detector in a strong magnetic field without significant mutual interference. In this study, we developed and tested a unilateral breast array coil specialized for MRSMM imaging. The electromagnetic field, specific absorption ratio and RF coil parameters with cadmium-zinc-telluride detectors encapsulated in specialized RF and gamma-ray shielding mounted within the RF coil were investigated through simulation and experimental measurements. Simultaneous MR and SMM images of a breast phantom were also acquired using the integrated MRSMM system. This work, we feel, represents an important step toward the fabrication of a working MRSMM system.

IEEE Transactions on Radiation and Plasma Medical Sciences

Improving 511 keV photon detection sensitivity is a common goal for positron emission tomography ... more Improving 511 keV photon detection sensitivity is a common goal for positron emission tomography system designers. One attractive approach to increase sensitivity is recovering events that are normally rejected. The kinematics of Compton scattering can be used to recover the line of response through direction difference angle (DDA). The uncertainty of DDA is determined by the energy and spatial resolution of a system. In this work, we evaluated the performance of small animal CZT-based positron emission tomography systems with energy resolution of 1%, 4%, and 6% and different spatial resolution based on prior work for guiding new design efforts. Designs with energy resolution limited by counting statistics and by electronic noise were considered. The influence of modifying the conventional energy window and uncertainty of DDA was investigated. For a system with 4% energy resolution and limited by electronic noise, the figure of merit of noise equivalent count increases by 65% as the lower energy bound increases from 471 keV to 493 keV. If the system-wide energy resolution becomes worse than 4% of the full width half maximum at 511 keV, going to a pixel size finer than 1 mm has very limited effect in reducing total angular uncertainty. For a system with 1% energy resolution, as the spatial resolution improves from 1 mm to 0.5 mm, the contrast-to-noise ratio increases by 9%.

AIP Conference Proceedings, 1981

AIP Conference Proceedings, 1976

A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used... more A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used as a polarized proton target. We measured a target density of 2×10&amp;amp;amp;amp;amp;amp;#39;&amp;amp;amp;amp;amp;amp;#39; atoms/cm3 and a target polarization of 0.37 without the use of r.f. transitions. These measurements indicate that a number of experiments are currently feasible with a variety of polarized target

AIP Conference Proceedings, 1981