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Initial characterization of a BGO-photodiode detector for high resolution positron emission tomography

Description: Spatial resolution in positron emission tomography is currently limited by the resolution of the detectors. This work presents the initial characterization of a detector design using small bismuth germanate (BGO) crystals individually coupled to silicon photodiodes (SPDs) for crystal identification, and coupled in groups to phototubes (PMTs) for coincidence timing. A 3 mm x 3 mm x 3 mm BGO crystal coupled only to an SPD can achieve a 511 keV photopeak resolution of 8.7% FWHM at -150/sup 0/C, us… more
Date: November 1, 1983
Creator: Derenzo, S.E.
Partner: UNT Libraries Government Documents Department
open access

Monte Carlo optimization of depth-of-interaction resolution in PET crystals

Description: The light distribution along one edge of a PET scintillation crystal was investigated with a Monte Carlo simulation. This position-dependent light can be used to measure the 511 keV photon interaction position in the crystal on an event by event basis, thus reducing radial elongation. The expected full width at half maximum (FWHM) of the light distribution on the 3 {times} 30 mm{sup 2} surface of a 3 {times} 10 {times} 30 mm{sup 3} bismuth germanate (BGO) crystal surrounded by a diffuse reflect… more
Date: November 1, 1991
Creator: DeVol, T. A. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Nuclear Engineering); Moses, W. W. & Derenzo, S. E. (Lawrence Berkeley Lab., CA (United States))
Partner: UNT Libraries Government Documents Department
open access

Multiple preequilibrium decay processes

Description: Several treatments of multiple preequilibrium decay are reviewed with emphasis on the exciton and hybrid models. We show the expected behavior of this decay mode as a function of incident nucleon energy. The algorithms used in the hybrid model treatment are reviewed, and comparisons are made between predictions of the hybrid model and a broad range of experimental results. 24 refs., 20 figs.
Date: November 1, 1987
Creator: Blann, M.
Partner: UNT Libraries Government Documents Department
open access

Improvements in Monte Carlo Simulation of Large Electron Fields

Description: Two Monte Carlo systems, EGSnrc and Geant4, were used to calculate dose distributions in large electron fields used in radiotherapy. Source and geometry parameters were adjusted to match calculated results with measurement. Both codes were capable of accurately reproducing the measured dose distributions of the 6 electron beams available on the accelerator. Depth penetration was matched to 0.1 cm. Depth dose curves generally agreed to 2% in the build-up region, although there is an additional 2… more
Date: November 28, 2007
Creator: Faddegon, Bruce A.; /UC, San Francisco; Perl, Joseph & Asai, Makoto
Partner: UNT Libraries Government Documents Department
open access

Inverse problem for in vivo NMR spatial localization

Description: The basic physical problem of NMR spatial localization is considered. To study diseased sites, one must solve the problem of adequately localizing the NMR signal. We formulate this as an inverse problem. As the NMR Bloch equations determine the motion of nuclear spins in applied magnetic fields, a theoretical study is undertaken to answer the question of how to design magnetic field configurations to achieve these localized excited spin populations. Because of physical constraints in the produc… more
Date: November 1, 1985
Creator: Hasenfeld, A.C.
Partner: UNT Libraries Government Documents Department
open access

Contributions and future of radioisotopes in medical, industrial and space applications

Description: There are 333 isotopes that have a half-life between 1 day and 100,000 years that have a wide variety of applications including public health, medicine,industrial technology, food technology and packaging, agriculture, energy supply, and national security. This paper provides an overview of some of the most extensive applications of radioisotopes including some observations of future uses. Examples are discussed that indicate that the use of radioisotopes is almost unlimited and will continue t… more
Date: November 1, 1990
Creator: Tingey, G. L.; Dix, G. P. & Wahlquist, E. J.
Partner: UNT Libraries Government Documents Department
open access

Materials evaluation for a transuranic processing facility

Description: The Westinghouse Hanford Company, with the assistance of the Pacific Northwest Laboratory, is developing a transuranium extraction process for preheating double-shell tank wastes at the Hanford Site to reduce the volume of transuranic waste being sent to a repository. The bench- scale transuranium extraction process development is reaching a stage where a pilot plant design has begun for the construction of a facility in the existing B Plant. Because of the potential corrosivity of neutralized … more
Date: November 1, 1990
Creator: Barker, S.A., Schwenk, E.B. (Westinghouse Hanford Co., Richland, WA (USA)) & Divine, J.R. (Pacific Northwest Lab., Richland, WA (USA))
Partner: UNT Libraries Government Documents Department
open access

Internal Radiation Dosimetry for Clinical Testing of Radiolabeled Monoclonal Antibodies

Description: In gauging the efficacy of radiolabeled monoclonal antibodies in cancer treatment, it is important to know the amount of radiation energy absorbed by tumors and normal tissue per unit administered activity. This paper describes methods for estimating absorbed doses to human tumors and normal tissues, including intraperitoneal tissue surfaces, red marrow, and the intestinal tract from incorporated radionuclides. These methods use the Medical Internal Radiation Dose (MIRD) scheme; however, they a… more
Date: November 1, 1990
Creator: Fisher, D. R.; Durham, J. S.; Hui, T. E. & Hill, R. L.
Partner: UNT Libraries Government Documents Department
open access

Spatially variant tomographic imaging: Estimation, identification, and optimization

Description: This thesis is an investigation of methods for processing multidimensional signals acquired using modern tomography systems that have an anisotropic or spatially variant response function. The main result of this research is the discovery of a new method to obtain better estimators of an unknown spatial intensity distribution by incorporating detailed knowledge about the tomograph system response function and statistical properties of the acquired signal into a mathematical model.
Date: November 1, 1991
Creator: Baker, J.R.
Partner: UNT Libraries Government Documents Department
open access

Semiconductor detectors for medical tomography with high-energy heavy ions

Description: High-energy heavy ion beams are in use at the Lawrence Berkeley Laboratory for cancer therapy. In order to take full advantage of the very favorable depth-dose characteristics of those beams, it is necessary to determine the stopping characteristics of the ions in the complex media of a human with greater accuracy than obtainable with x-ray CAT scanning. Initial measurements with an array of Si dE/dx position sensitive detectors and a windowless thin planar Ge detector used in a side entry mode… more
Date: November 1, 1980
Creator: Llacer, J.; Haller, E. E.; Hansen, W. L.; Walton, J. T. & Batho, E. K.
Partner: UNT Libraries Government Documents Department
open access

Imaging properties of a positron tomograph with 280 BGO crystals

Description: The basic imaging properties of the Donner 280-BGO-Crystal positron tomograph were measured and compared with the same system when it was equipped with 280 NaI(T1) crystals. The NaI(T1) crystals were 8 mm x 30 mm x 50 mm deep, sealed in 10 mm wide stainless steel cans. The BGO crystals are 9.5 mm x 32 mm x 32 mm deep and as they are not hygroscopic do not require sealed cans. With a shielding gap of 3 cm (section thickness 1.7 cm FWHM) the sensitivity of the BGO system is 55,000 events per sec … more
Date: November 1, 1980
Creator: Derenzo, S.E.; Budinger, T.F.; Huesman, R.H.; Cahoon, J.L. & Vuletich, T.
Partner: UNT Libraries Government Documents Department
open access

Compensation for crystal penetration in high resolution positron tomography

Description: We have characterized the effects of crystal penetration by annihilation photons in circular ring positron tomographs. They are most serious in high resolution instruments having small detectors. When annihilation photons are not normally incident and penetrate some distance into the scintillator before interacting, the measurement of their transverse position becomes uncertain. This penetration of photons into the detector material before interaction is a statistical process which leads to sig… more
Date: November 1, 1988
Creator: Huesman, R.H.; Salmeron, E.M. & Baker, J.R.
Partner: UNT Libraries Government Documents Department
open access

The development of a Compton lung densitometer

Description: A field instrument is being developed for the non-invasive determination of absolute lung density using unique Compton backscattering techniques. A system consisting of a monoenergetic gamma-ray beam and a shielded high resolution high-purity-germanium (HPGe) detector in a close-coupled geometry is designed to minimize errors due to multiple scattering and uncontrollable attenuation in the chestwall. Results of studies on system performance with phantoms, the optimization of detectors, and the … more
Date: November 1, 1988
Creator: Loo, B. W.; Goulding, F. S.; Madden, N. W. & Simon, D. S.
Partner: UNT Libraries Government Documents Department
open access

The Tuning Algorithms Used by the Donner 600 Crystal Tomograph

Description: We describe the computer algorithms used to adjust the energy thresholds and timing delays in the Donner 600 Crystal Tomograph. These thresholds and delays are adjusted using 1890 computer controlled digital to analog converters (DAC's) and a orbiting positron source. The energy threshold for each crystal is adjusted by measuring the counting rate of each crystal-crystal coincidence as a function of the DAC settings that control a pulse height window for the crystal in question. The DAC setting… more
Date: November 1, 1988
Creator: Moses, W. W.; Derenzo, S.E.; Geyer, A. B.; Huesman, R. H. & Uber, D. C.
Partner: UNT Libraries Government Documents Department
open access

Development of magnetic resonance technology for noninvasive boron quantification

Description: Boron magnetic resonance imaging (MRI) and spectroscopy (MRS) were developed in support of the noninvasive boron quantification task of the Idaho National Engineering Laboratory (INEL) Power Burst Facility/Boron Neutron Capture Therapy (PBF/BNCT) program. The hardware and software described in this report are modifications specific to a GE Signa{trademark} MRI system, release 3.X and are necessary for boron magnetic resonance operation. The technology developed in this task has been applied to … more
Date: November 1, 1990
Creator: Bradshaw, K.M.
Partner: UNT Libraries Government Documents Department
open access

Proton therapy construction projects in the United States

Description: Proton and heavy-ion radiation therapy has been taking place now for 40 years, at many accelerator laboratories around the world, essentially all of these centers built originally for physics research. The high degree of promise shown for using these particles for treating and curing cancer has stimulated the medical community to look seriously at building dedicated accelerator facilities in a hospital setting, where more rapid progress can be made in clinical research, and development of effec… more
Date: November 1, 1992
Creator: Alonso, J. R.
Partner: UNT Libraries Government Documents Department
open access

Spatially variant tomographic imaging: Estimation, identification, and optimization

Description: This thesis is an investigation of methods for processing multidimensional signals acquired using modern tomography systems that have an anisotropic or spatially variant response function. The main result of this research is the discovery of a new method to obtain better estimators of an unknown spatial intensity distribution by incorporating detailed knowledge about the tomograph system response function and statistical properties of the acquired signal into a mathematical model.
Date: November 1, 1991
Creator: Baker, J. R.
Partner: UNT Libraries Government Documents Department
open access

Monte Carlo optimization of depth-of-interaction resolution in PET crystals

Description: The light distribution along one edge of a PET scintillation crystal was investigated with a Monte Carlo simulation. This position-dependent light can be used to measure the 511 keV photon interaction position in the crystal on an event by event basis, thus reducing radial elongation. The expected full width at half maximum (FWHM) of the light distribution on the 3 {times} 30 mm{sup 2} surface of a 3 {times} 10 {times} 30 mm{sup 3} bismuth germanate (BGO) crystal surrounded by a diffuse reflect… more
Date: November 1, 1991
Creator: DeVol, T. A.; Moses, W. W. & Derenzo, S. E.
Partner: UNT Libraries Government Documents Department
open access

Optimal x-ray energy for digital mammography

Description: Screening mammography is a radiological procedure requiring the highest possible image quality at the lowest possible dose. It is widely recognized that digital image acquisition, computer assisted diagnosis, and scientific visualization can provide substantial improvement in mammography. For such systems, much of what is accepted as best practice with today`s film/screen/lightbox systems will become inappropriate. A complete system design is required. We have constructed a model of the breast … more
Date: November 1, 1992
Creator: Logan, C. M.; Hernandez, J. M.; Kinney, J. H. & Lewis, D. L.
Partner: UNT Libraries Government Documents Department
open access

C.A.S.I.S. Workshop 2003 Abstract Proceedings

Description: Thirty five years ago, while in the neutron cross section group led by Robert Howerton at LLNL, the concept of reconstructing a three dimensional spatial distribution from its projections onto two dimensional planes was tackled by some of us using three now well known methods: simple back projection, Fourier projection theorem methods and iterative least squares algebraic reconstruction. The method of iterative least squares reconstruction was implemented on patient data in the early 1970s usin… more
Date: November 10, 2003
Creator: Azevedo, S
Partner: UNT Libraries Government Documents Department
open access

Biological effects of radiation and related biochemical and physical studies. Proposal 3. Metabolic studies in cancer with radioactive isotopes. Progress report, October 1, 1975--September 30, 1976. [Lead]

Description: Separate abstracts were prepared for seven sections of this report that discuss diagnostic techniques using radioisotopes as tracers.
Date: November 12, 1976
Creator: Laughlin, J. S. & Myers, W. P. L.
Partner: UNT Libraries Government Documents Department
open access

Enhancement of digital images by modeling two-dimensional surfaces

Description: A method of digital image processing is described which can be used to improve the quality of radiographic images. An image is modeled as the sum of background information, details of interest, and noise. The background is then modified in order to enhance the details. 5 figures.
Date: November 3, 1976
Creator: Huebel, J. G. & Myers, G. K.
Partner: UNT Libraries Government Documents Department
open access

Production capabilities in US nuclear reactors for medical radioisotopes

Description: The availability of reactor-produced radioisotopes in the United States for use in medical research and nuclear medicine has traditionally depended on facilities which are an integral part of the US national laboratories and a few reactors at universities. One exception is the reactor in Sterling Forest, New York, originally operated as part of the Cintichem (Union Carbide) system, which is currently in the process of permanent shutdown. Since there are no industry-run reactors in the US, the n… more
Date: November 1, 1992
Creator: Mirzadeh, S.; Callahan, A. P.; Knapp, F. F. Jr. & Schenter, R. E.
Partner: UNT Libraries Government Documents Department
open access

Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

Description: We present initial performance results for a new multi-layer PET detector module consisting of an array of 3 mm square by 30 mm deep BGO crystals coupled on one end to a single photomultiplier tube and on the opposite end to an array of 3 mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for the all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25{degr… more
Date: November 1, 1992
Creator: Moses, W. W.; Derenzo, S. E.; Nutt, R.; Digby, W. M.; Williams, C. W. & Andreaco, M.
Partner: UNT Libraries Government Documents Department
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