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Investigations into the Optimization of Multi-Source Strength Brachytherapy Treatment Procedures

Description: The goal of this project is to investigate the use of multi-strength and multi-specie radioactive sources in permanent prostate implant brachytherapy. In order to fulfill the requirement for an optimal dose distribution, the prescribed dose should be delivered to the target in a nearly uniform dose distribution while simultaneously sparing sensitive structures. The treatment plan should use a small number of needles and sources while satisfying the treatment requirements. The hypothesis for the use of multi-strength and/or multi-specie sources is that a better treatment plan using fewer sources and needles could be obtained than by treatment plans using single-strength sources could reduce the overall number of sources used for treatment. We employ a recently developed greedy algorithm based on the adjoint concept as the optimization search engine. The algorithm utilizes and ''adjoint ratio'', which provides a means of ranking source positions, as the pseudo-objective function. It ha s been shown that the greedy algorithm can solve the optimization problem efficiently and arrives at a clinically acceptable solution in less than 10 seconds. Our study was inclusive, that is there was no combination of sources that clearly stood out from the others and could therefore be considered the preferred set of sources for treatment planning. Source strengths of 0.2 mCi (low), 0.4 mCi (medium), and 0.6 mCi (high) of {sup 125}I in four different combinations were used for the multi-strength source study. The combination of high- and medium-strength sources achieved a more uniform target dose distribution due to few source implants whereas the combination of low-and medium-strength sources achieved better sparing of sensitive tissues including that of the single-strength 0.4 mCi base case. {sup 125}I at 0.4 mCi and {sup 192}Ir at 0.12 mCi and 0.25 mCi source strengths were used for the multi-specie source study. This study also proved inconclusive ...
Date: September 30, 2002
Creator: Henderson, D. L.; Yoo, S. & Thomadsen, B.R.
Partner: UNT Libraries Government Documents Department

Testing the validity of a receptor kinetic model via TcNGA functional imaging of liver transplant recipients. Final report

Description: The author had accomplished the expertise for I-125-HSA plasma volume, galactose clearance for determination of hepatic plasma flow as well as finalizing the kinetic model. They have just completed modifying the microscale Scatchard assay for greater precision of receptor measurement using only 5--10 mg of liver tissue. In addition, he determined during the past year that the most practical method and clinically reasonable measurement of liver volume was to measure the transplanted liver in vivo using Tc-NGA images in the anterior, posterior, and right lateral projections, using the method of Rollo and DeLand. Direct measurement of liver weight obtained during transplant operation was not reliable due to variability of fluid retention in the donor liver secondary to ischemia, preservation fluid, etc., which thereby did not reflect an accurate liver weight which is needed in the kinetic analysis comparison, i.e., V{sub h} (hepatic plasma volume).
Date: March 25, 1993
Creator: Stadalnik, R. C.
Partner: UNT Libraries Government Documents Department

Development of novel epidermal growth receptor-basedradiopharmaceuticals: Imaging agents for breast cancer

Description: The goal of this research was to develop epidermal growthfactor receptor (EGFR) nuclear medicine breast cancer imaging agents. Ourapproach was to synthesize small molecule inhibitors of the EGFR tyrosinekinase (tk) suitable for labeling with single photon or positron-emittingradioisotopes and evaluate the imaging potential of these new molecules.We have synthesized and fully characterized 22 quinazoline compounds. Allcompounds inhibit EGFR tk phosphorylation activity in the nanomolarrange. All compounds tested exhibited specificity for the EGFR tk versusthe ErbB2 and ErbB4 tyrosine kinases. A radiometric binding assay usingan iodine-125 labeled quinazoline was developed to determine the affinityof the quinazolines for the EGFR tk ATP binding site. The affinitiesranged from 0.4-51 nM. The octanol/water partition coefficients (Log P;lipophilicity) of the new compounds ranged from 2.2-5.5. Six compoundshave been labeled with fluorine-18. Biodistribution in EGFRoverexpressing tumor bearing mice demonstrated tumor uptake buthighlighted delivery and metabolism issues. The 2-fluoro quinazoline wasnot metabolized in an in vitro hepatocyte study. From this work a breadthof agent characteristics was created establishing the foundation forfuture research toward the optimal EGFR imaging agent.
Date: September 25, 2001
Creator: Van Brocklin, Henry F.
Partner: UNT Libraries Government Documents Department

Measurement of the Bovine pancreatic trypsin inhibitors by radioimmunoassay

Description: Bovine pancreas contains two polypeptide trypsin inhibitors that are not homologous and differ in their inhibitory activity towards chymotrypsin, kallikrein, elastase, and other serine proteinases. The Kunitz inhibitor and the Kazal inhibitor are present in approximately equimolar concentrations in bovine pancreatic tissue, yet only the Kazal inhibitor is detectable in the pancreatic juice. The Kazal inhibitor has been named the pancreatic secretory trypsin inhibitor, PSTI because its concentration in the pancreatic juice parallels that of the exocrine secretory proteins. The Kunitz inhibitor is considered the intracellular inhibitor, however, no direct information is available concerning the intracellular localization of these inhibitors in the pancreas. The preparation of /sup 125/I-labeled derivatives of Kazal and Kunitz inhibitors by the lactoperoxidase method and a radioimmunoassay for each inhibitor are described. (auth)
Date: January 1, 1973
Creator: Fink, E. & Greene, L.J.
Partner: UNT Libraries Government Documents Department

Receptor-DNA binding to target auger electrons for cancer therapy. Final report, August 1, 1993--January 31, 1997

Description: The goal of this program was to investigate the principle of receptor-DNA binding as a means to target Auger electron radiation for cancer therapy, and thereby to evaluate the potential of non-covalent, high-affinity, Auger electron-emitting ligands binding to a DNA associated molecule, or DNA itself, for cancer therapy. These studies were intended to assess the ability of Auger-emitting estrogens to kill estrogen receptor-positive tumor cells, determine the mean lethal dose, and determine whether they could be effective in vitro and in vivo.
Date: May 1, 1997
Creator: DeSombre, E.R.
Partner: UNT Libraries Government Documents Department

Production of fission and activation product isotopes at Sandia National Laboratories

Description: The mission of the Sandia National Laboratories (SNL) Annular Core Research Reactor (ACRR) and the Hot Cell Facility (HCF) has recently changed from support of Defense and other programs to support of the Department of Energy (DOE) Isotope Production and Distribution Program (IPDP). SNL`s primary role, in support of IPDP, is ensuring a reliable supply of {sup 99}Mo to the US health care system. SNL will also play a role of complementing the isotope production of other DOE Reactor facilities such as High Flux Isotope Reactor (HFIR) at Oak Ridge, Tennessee; High Flux Beam Reactor (HFBR) at Brookhaven, New York, ad Advanced Test Reactor (ATR) in Idaho. The unique characteristics that the SNL facilities offer to the IPDP facility capability are simplicity, multiple irradiation locations, ready irradiation space access and co-located hot cell facilities capable of processing a short decay fission product stream. The SNL {sup 99}Mo effort is characterized elsewhere and this paper is intended to describe the production of additional isotopes for that can be produced medical and other uses planned to start soon after the {sup 99}Mo capability has been established. Isotope production in the SNL facilities is through fission or by neutron activation.
Date: August 1, 1997
Creator: Coats, R.L.
Partner: UNT Libraries Government Documents Department

High Resolution Detector Modules Based on NaI(T1) Arrays for Small Animal Imaging

Description: We are developing high spatial resolution detector modules based on recently available NaI(T1) crystal scintillator arrays that are capable of detecting photons over a range of energies. We report on the testing of an array with individual element sizes of 1 mm x 1 mm arrays over the energy range of 28 keV to 511 keV. It is anticipated that these detector modules could be applied to small animal imaging utilizing single photon emitters such as iodine-125 (28-35 keV) and technetium-99m (140 keV); and also positron emitters such as fluorine-18. The performance of a 5 cm square array of NaI(T1) crystal scintillators in which each element is 1 mm x 1 mm x 5 mm in dimension was measured. The NaI(T1) array manufactured by Saint-Gobain was coupled to Hamamatsu position sensitive photomultiplier tubes and tested over a range of photon energies. In particular, we tested the NaI(T1) array with the Hamamatsu model R2487 position sensitive photomultiplier tube and the new Hamamatsu model 85 00 flat panel position sensitive photomultiplier tube. Though the NaI(T1) module performed best for the single photon emitters its use in positron emission tomography applications for small animal imaging could be possible even though resulting sensitivity is not ideal.
Date: November 1, 2001
Creator: Weisenberger, A.G.; Wojcik, R.; Majewski, S. & Popov, V.
Partner: UNT Libraries Government Documents Department

Epidermal growth factor (EGF) as a potential targeting agent for delivery of boron to malignant gliomas

Description: The majority of high grade gliomas express an amplified epidermal growth factor receptor (EGFR) gene, and this often is associated with an increase in cell surface receptor expression. The rapid internalization and degradation of EGF-EGFR complexes, as well as their high affinity make EGF a potential targeting agent for delivery of {sup 10}B to tumor cells with an amplified number of EGFR. Human glioma cells can expresses as many as 10{sup 5} {minus}10{sup 6} EGF receptors per cell, and if these could be saturated with boronated EGF, then > 10{sup 8} boron atoms would be delivered per cell. Since EGF has a comparatively low molecular weight ({approximately} 6 kD), this has allowed us to construct relatively small bioconjugates containing {approximately} 900 boron atoms per EGF molecule{sup 3}, which also had high affinity for EGFR on tumor cells. In the present study, the feasibility of using EGF receptors as a potential target for therapy of gliomas was investigated by in vivo scintigraphic studies using {sup 131}I{minus} or {sup 99m}{Tc}-labeled EGF in a rat brain tumor model. Our results indicate that intratumorally delivered boron- EGF conjugates might be useful for targeting EGFR on glioma cells if the boron containing moiety of the conjugates persisted intracellularly. Further studies are required, however, to determine if this approach can be used for BNCT of the rat glioma.
Date: December 31, 1994
Creator: Capala, J.; Barth, R.F.; Adams, D.M.; Bailey, M.Q.; Soloway, A.H. & Carlsson, J.
Partner: UNT Libraries Government Documents Department

Research in nuclear physics. Progress report, 1992--1993

Description: This report discusses the following topics: Search for Massive Neutrinos in the Recoil Spectrum of {sup 37}Cl following Electron Capture Decay of {sup 37}Ar; A Monte Carlo Simulation of the Electron Capture Decay of {sup 37}Ar with an Admixture of Massive Neutrinos: Search for 17-keV Neutrinos in the Internal Bremsstrahlung Spectrum of {sup 125}I; {beta}{sup +} Decay and Cosmic-Ray Half-Lives of {sup 143}Pm and {sup 144}Pm; and Production Cross Sections from the Bombardment of Natural Mo with Protons.
Date: June 1, 1993
Creator: Kozub, R. L. & Hindi, M. M.
Partner: UNT Libraries Government Documents Department

[Studies on the interaction of blood components with ultra-smooth polymer surfaces]

Description: This report is in three parts, though each is briefly described data is provided. The three parts address (1) radioiodination of human thrombin and fibrinogen; (2) interaction of blood components with ultra- smooth polymer surfaces; and (3) initial studies of Tecoflex and treated Tecoflex cups with normal serum samples.
Date: April 17, 1989
Creator: Carlson, T. H.
Partner: UNT Libraries Government Documents Department

Quantitative autoradiographic microimaging in the development and evaluation of radiopharmaceuticals

Description: Autoradiographic (ARG) microimaging is the method for depicting biodistribution of radiocompounds with highest spatial resolution. ARG is applicable to gamma, positron and negatron emitting radiotracers. Dual or multiple-isotope studies can be performed using half-lives and energies for discrimination of isotopes. Quantitation can be performed by digital videodensitometry and by newer filmless technologies. ARG`s obtained at different time intervals provide the time dimension for determination of kinetics.
Date: April 1, 1994
Creator: Som, P. & Oster, Z. H.
Partner: UNT Libraries Government Documents Department

Assessment of the sources of error affecting the quantitative accuracy of SPECT imaging in small animals

Description: Small animal SPECT imaging systems have multiple potential applications in biomedical research. Whereas SPECT data are commonly interpreted qualitatively in a clinical setting, the ability to accurately quantify measurements will increase the utility of the SPECT data for laboratory measurements involving small animals. In this work, we assess the effect of photon attenuation, scatter and partial volume errors on the quantitative accuracy of small animal SPECT measurements, first with Monte Carlo simulation and then confirmed with experimental measurements. The simulations modeled the imaging geometry of a commercially available small animal SPECT system. We simulated the imaging of a radioactive source within a cylinder of water, and reconstructed the projection data using iterative reconstruction algorithms. The size of the source and the size of the surrounding cylinder were varied to evaluate the effects of photon attenuation and scatter on quantitative accuracy. We found that photon attenuation can reduce the measured concentration of radioactivity in a volume of interest in the center of a rat-sized cylinder of water by up to 50percent when imaging with iodine-125, and up to 25percent when imaging with technetium-99m. When imaging with iodine-125, the scatter-to-primary ratio can reach up to approximately 30percent, and can cause overestimation of the radioactivity concentration when reconstructing data with attenuation correction. We varied the size of the source to evaluate partial volume errors, which we found to be a strong function of the size of the volume of interest and the spatial resolution. These errors can result in large (>50percent) changes in the measured amount of radioactivity. The simulation results were compared with and found to agree with experimental measurements. The inclusion of attenuation correction in the reconstruction algorithm improved quantitative accuracy. We also found that an improvement of the spatial resolution through the use of resolution recovery techniques (i.e. modeling the ...
Date: February 15, 2008
Creator: Joint Graduate Group in Bioengineering, University of California, San Francisco and University of California, Berkeley; Department of Radiology, University of California; Gullberg, Grant T; Hwang, Andrew B.; Franc, Benjamin L.; Gullberg, Grant T. et al.
Partner: UNT Libraries Government Documents Department