2020 Health Physics Society Midyear Meeting & ExhibitionP
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P.1 Modelling Energy Deposition in Silica and Carbonate Sands Using MCNP. Graham Hannah R.*, The University of Ontario Institute of Technology; Waller Edward J., The University of Ontario Institute of Technology hannah.graham@ontariotechu.net
When modelling various scenarios, it is important to accurately model the various environments that are found. In order to see what level of detail is needed, two different types of sand were modeled to see if there was a significant difference in the energy deposition between sand types. Two of the most common types of sand are silica-based sands and Carbonate sands, therefore these two types were modeled and compared to each other. Monte Carlo N-Particle (MCNP) was used to model Cs-137 in two compositions of Lithic silica sands. A fish egg on the surface of the sand, as well as a trout above the sand were used as tallies to collect the energy deposition in these organisms. For the trout, the percent difference between the two silica compositions was ~5%. For the comparison between the silica sand and carbonate sand the percent difference was between ~9-15%. For the egg, the percent difference was only ~1% for the silica compositions. For the comparison between the silica sand and carbonate sand the percent difference was between ~5-6%. The results for the egg are not unexpected, since the majority of the particles completely miss the egg due to their energy. |
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P.2 Pitchblende. A Philatelic Look At Health Physics History. Johnston Thomas P.*, NIST tjohnstn@gmail.com
Pitchblende is also known as uraninite. The word comes from pitch or pech, meaning black or bad luck because of its black color, and blende. As health physicists we know about pitchblende and the work of Marie Skłodowska Curie and Pierre Curie in 1903. This poster will review the known uses of Uranium over time and the story is told with a graphical accompaniment of philatelic material (postage stamps). The story featuring Uranium begins with: the work of the Curie's, highlights the natural reactor in Gabon, a discovery of the first use of Uranium in Rome, miner's lung disease in the 1500's, a tie-in with President Herbert Hoover, a coloring agent for the ceramic and glass industries, silver mines and the U.S. dollar, more connections to the Curies and Becquerel, revelation of where those Coleman lantern mantles came from, a link to respiratory protection, spas in Jáchymov, and the final stamp courtesy of Fiestaware. |
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P.3 Comparison of Age-Specific Dose Rate Coefficients in Federal Guidance Report No. 15. Stuenkel David O.*, U.S. Environmental Protection Agency; Boyd Michael A., U.S. Environmental Protection Agency stuenkel.david@epa.gov
In August 2019, the U.S. Environmental Protection Agency published Federal Guidance Report No. 15 (FGR 15), External Exposure to Radionuclides in Air, Water and Soil. The report updates and expands Federal Guidance Report No. 12, published in 1993, and provides age-specific reference person effective dose rate coefficients for 1,252 radionuclides six different age groups based on external exposure to radionuclides distributed in air, water or soil. FGR 15 also included updated tissue weighting factors (as recommended in ICRP Publication 103) and radionuclide decay data (as provided in ICRP Publication 107) and calculated using improved computing power to provide more precise results than previous results. Age groups include a newborn, 1-year old, 5-year old, 10-year old, 15-year old, and an adult. Dose rate coefficients for the five youngest age groups were compared to those of the adult age group to assess the impact of using age-specific coefficients. For all radionuclides, the effective dose rate coefficients for the five youngest age groups were greater than those for the adult age group, though about 90% or more were within a factor of 2. In a few instances, dose rate coefficients varied by a factor of approximately 20. Relative differences were greatest between the adult and the infant age groups with the relative differences decreasing as the differences in the ages between age groups decreased. Use of age-specific dose rate coefficients in FGR 15 for younger age groups will provide improved estimates of external dose rates that will be higher than those of the adult age group by a factor of 2 or less for most radionuclides. |
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P.4 Development of a Ga2O3-based Fast Neutron Imaging and Spectroscopic System. Stanley D Hunter *, NASA GSFC; J. Derek Demaree , ARL APG; Guardala Noel, George Washington University nguardala76@gwu.edu
We have performed a number of preliminary measurements related to the basic response of n-doped Ga2O3 (provided by NRL) in scintillator mode to a variety of ionizing radiation sources including Spontaneous Fission neutrons from both 252Cf source, and Depleted Uranium, DU and 14.3 MeV neutrons from a D-T neutron generator Using the NRL grown Ga2O3 characteristic spectra using a very simple detector arrangement with four rectangular crystals each 600 microns thick were obtained. Based on these results it is proposed that n-doped Ga2O3 can be effectively used in systems designed to be either fast neutron spectrometers or Omni-Directional fast neutron imager. These crystals were also found to be insensitive to gamma radiation for photons with energies greater than 40 keV. Potential applications for both the spectroscopic and imaging systems will be discussed as they pertain to a number of conditions where fast neutrons are emitted. |
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P.5 STATE OF RADIATION PROTECTION PRACTICE BY RADIOLOGIC TECHNOLOGISTS AT SAUDI PEDIATRIC HOSPITALS. Almashhki Ahmed* Ahmed.Almashhki@gmail.com
Medical radiation protection is best achieved when radiologic technologists are fully aware of its requirements and regulations because they are the front line radiation service providers, particularly at pediatric centers. This project aimed at evaluating Saudi radiologic technologists’ knowledge and extent of actual practice. A total of 12 pediatric hospitals in five regions of Saudi Arabia were included. An online survey containing 26 questions was sent via e-mail and WhatsApp to approximately 1,000 radiologic technologists, of which 269 responses were completed (Rates: 61% and 27%, respectively). Radiation protection knowledge gaps among practicing radiologic technologists was at 47%, with varying degrees. The practice gap was greater as a clear majority did not shield sensitive areas or practice uniform ALARA methods. As a result as set of corrective measure were developed. This poster will present the current status of radiation safety practices at Saudi pediatric centers and proposed corrective actions. |
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P.6 Iso-center shift results in increases patient dose indices in pediatric computed tomography. Silvestrini Eugenio*, Northwell Health; O'Connell William J, Northwell Health esilvestrini@me.com
The purpose of this study is to estimate the relationship between patient positioning and applicable dose indices in pediatric computed tomography examinations. Specifically, the study will examine the variation in patient dose indices with deviation from iso-center in clinical examinations. 8,500 pediatric computed tomography examinations were performed on fifty-two computed tomography scanners during 2018. Volumetric Computed Tomography Index (CTDIVOL), Dose Length Product (DLP) and Effective Dose (EICRP-103) were collected and analyzed with a commercial radiation dose index monitoring (RDIM) system. The effect of x- and y- offset were analyzed and reported as percent deviation from the applicable dose index for well positioned patients. Results show the CTDIVOL increased by as much as 256% for pediatric CT examinations deviating more than 2 cm off isocenter. DLP increased by as much as 282% for examinations deviating more than 2 cm off isocenter and EICRP-103 increased by up to 174% for examinations deviating more than 2 cm off isocenter. Patients positioned off isocenter confound dose optimization efforts. Misalignment with the bowtie filter results in increased dose and diminished image quality. The dose effect is more prominent when the isocenter shift occurs in the vertical direction when compared to misalignment in the lateral direction. |
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P.7 Physicians And Radiologists, And Other Contributors To The Health Sciences. A Philatelic Look At Health Physics History. Johnston Thomas P.*, NIST tjohnstn@gmail.com
With almost immediate certainty and in all likelihood, these physicians, radiologists, and other contributors to the health sciences depicted here were unknown to most people today. Yet these individuals were selected by the particular country’s postal authority to be commemorated on a postage stamp. |
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P.8 Space Applications With Radiation Sources And Detectors, Part 1. A Philatelic Look At Health Physics History. Johnston Thomas P. *, NIST tjohnstn@gmail.com
This health physics history installment illustrated with postage stamps ventures towards the heavens. On 7 December 1972 this author first visited the NASA complex at Cape Canaveral. The date is memorable since at 12:33 a.m. our family witnessed the launch of Apollo 17 at Cape Canaveral from Launch Complex 39. Apollo 17 was the last mission to land men on the moon and the only night launch. An interesting note: NASA was concerned about and protection measures were initiated with respect to radiation dose. The space radiation environment involved Van Allen belt radiation, solar particle events, cosmic rays, and neutrons. There was also exposure to Pm-147 and H-3 used for radioluminescent switch tips, control panels, and lighting. For over 50 years, space nuclear power sources have been successfully deployed to provide electrical power and used as heat sources for satellites and spacecraft. The missions include the Apollo Lunar Surface Experiment Packages; the Pioneer flybys of Jupiter and Saturn; the Viking Mars landers; the Voyager flybys of Jupiter, Saturn, Uranus, and Neptune; the Galileo orbital exploration of Jupiter; the Ulysses solar polar explorer; the Cassini orbital exploration of Saturn; and, most recently, the New Horizons mission to the Pluto/Charon system. |
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P.9 Space Applications With Radiation Sources And Detectors, Part 2. A Philatelic Look At Health Physics History. Johnston Thomas P.*, NIST tjohnstn@gmail.com
For the next part of this health physics history segment, space craft are portrayed on postage stamps along with diagrams and illustrations. Since 1961, the U.S. has successfully launched 46 nuclear power sources (45 radioisotope thermoelectric generators (RTG) and one nuclear reactor) on 25 space missions along with hundreds of radioisotope heater units (RHU). The SNAP-10A space nuclear reactor power system demonstrated the viability of automatically controlled, liquid-metal-cooled reactors for space applications. The radioisotope thermoelectric generators have enabled some of the most challenging and scientifically exciting missions in human history. |
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P.10 Ships And Submarines. A Philatelic Look At Health Physics History. Johnston Thomas P.*, N.I.S.T. tjohnstn@gmail.com
The author’s story of U.S. nuclear powered vessels: ships and submarines. The story begins by way of fascination with science, and adventure and enjoyment gained through reading. Introduction to this topic came via discovery of Jules Verne’s Twenty Thousand Leagues Under the Seas: A Tour of the Underwater World. This classic describes Captain Nemo’s wonderful existence aboard the Nautilus and the undersea adventures capable with an electric powered submarine. The youngster next experienced a close encounter with Nemo’s Nautilus on 7 December 1972 during a visit to Disneyworld and a ride on Walt Disney’s version. This date is memorable since that evening our family witnessed firsthand the night launch of Apollo 17 at Cape Canaveral. Apollo 17 was also the last Apollo mission to land men on the moon. An interesting note: NASA was concerned about, and protection measures were initiated with respect to radiation dose. Not only the cosmic radiation, but also exposure to the Pm-147 used to illuminate switches and control panels, and from the H-3 (tritium) used for radioluminescent lighting. |
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P.11 World List Of Early Nuclear Reactors, Africa And Asia. A Philatelic Look At Health Physics History. Johnston Thomas P.*, NIST tjohnstn@gmail.com
Presented here we have a review of the early days of nuclear reactors worldwide. This poster will briefly cover the commemorative postal stamps of the countries that chose to honor the first operational nuclear reactor in their nation. In particular, a summary of some of the countries in Africa and Asia with reactors featured on their postal issues. These early reactors were generally of the research and test reactor type. Note: TRIGA reactor – Training, Research, Isotope production, General Atomics. |
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P.12 World List Of Early Nuclear Reactors, The Americas And Antarctica. A Philatelic Look At Health Physics History. Johnston Thomas P.*, NIST tjohnstn@gmail.com
Presented here we have a review of the early days of nuclear reactors worldwide. We continue and finish with a final review of nuclear reactors featured on the postal issues of countries in the Americas and a special cancel from Antarctica. Several of the commemorative stamps feature the atomic or nuclear energy commission of the respective country, or the IAEA. There are a few stamps that highlight nuclear reactors. In general, after a mention of the United States and Puerto Rico, followed by Antarctica, we will cover the countries of the Americas in alphabetical order. |
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P.13 World List Of Early Nuclear Reactors, Europe. A Philatelic Look At Health Physics History. Johnston Thomas P.*, NIST tjohnstn@gmail.com
Presented here we have a review of the early days of nuclear reactors worldwide. We continue with a review of initial examples of nuclear reactors in Europe. This poster will briefly cover the commemorative postal stamps of the countries that elected to honor the first operational nuclear reactor in their nation. In particular, a brief review of the countries of the European continent with reactors featured on their postage stamp issues. |