P - Poster Session Exhibit Hall 13:00 - 15:00
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P. Poster
Estimation of Average Radiation Dose by Age Due to General Radiographic Examinations My Lee, Kyung Hee University, Republic of Korea
; Hw Nam, Kyung Hee University, Republic of Korea; Hj Na, Kyung Hee University, Republic of Korea; Bm Lee, Kyung Hee University, Republic of Korea; KP Kim*, Kyung Hee University, Republic of Korea
Abstract: General radiography is important tool in modern medicine. General radiography comprises the largest number of examinations in Korea. Its usage has been increasing over time. In 2017, the number of general radiography examinations was 220 million, representing for 78% in total diagnostic radiology usage. Increasing usage of medical radiology may result in higher public exposure. The objective of this study was to estimate average effective dose due to general radiographic examinations by age. Average ESD and x-ray technical parameter settings (kVp, mAs, etc) in Korea were collected to calculate the radiation doses. The data for chest PA, abdomen AP, and pelvis AP examinations of various patient ages were collected. The collected data were used with phantoms and a radiation transport code. The effective doses for chest PA examinations were 0.04, 0.05, and 0.07 mSv for 10y, 15y, and adult, respectively. The effective doses for Abdomen AP examinations were 0.19, 0.36, and 0.39 mSv by patient age. The effective doses for Pelvis AP examinations were 0.15, 0.26, and 0.31 mSv by patient age. The calculated radiation doses were the highest for adult patient. Generally higher ESD is used when the body thickness of patient is large. This study results will be used as representative radiation dose data for general radiography in Korea. * This work was supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KoFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea. (No. 1803013)
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P. Poster
Analysis of foreign representative person concepts to establish appropriate representative person concept for domestic dose assessment HS Seo, KyungHee university
; KH Kim, KyungHee university; YH Jin, KyungHee university; KP Kim*, KyungHee university
Abstract: ICRP published the ICRP 101 report and recommended applying the concept of representative person to reasonably assess radiation doses to the public. However, the maximum exposure individual concept for the dose assessment has been used in Korea. Therefore, it is necessary to adopt the representative person concept in the Korean regulation system. The objective of this study is to analyze foreign representative person concepts and appropriately adapt the representative person concept in Korea. ICRP, IAEA, UK, and Canada have used the representative person concept for individuals to represent radiation dose to the general public. The definition of a representative person is an average member of the critical group who received more exposure. The critical group should be defined as the actual person who can exist. The exposed age group was set up in three age groups, including 1-year, 10-year, and adult residents. The representative person’s habit data for the dominant exposure pathways were set at 95 percentile intakes and applied reasonably based on the exposure group. The result of this study can be used as a prior study for the introduction of the representative person concept recommended by ICRP 103 in Korea in the future. *This work was supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KoFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea. (No.1805016).
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P. Poster
Radioactive Potassium (K-40) in All Purpose Fertilizers (13-13-13), an Estimated and Experimental Approach JP Billa*, Centerville High School, Clifton, VA 20124
; SK Adzanu, Alcorn State University, Lorman, MS 39096; SP Didla, Alcorn State University, Lorman, MS 39096; MA Atkins, Alcorn State University, Lorman, MS 39096; JK Billa, Alcorn State University, Lorman, MS 39096
Abstract: Fertilizers are prominent resources that can provide plants with key nutrients and significantly enhance plant growth. One of the prominent fertilizers (All-purpose fertilizers (13-13-13)) is a widely used product in the landscaping industry as part providing nutrients to lawns, shrubs, flowers, and gardens. Phosphate and Potash rocks are some of the key ingredients used in production of fertilizers. Rocks tend to contain trace quantities of naturally occurring radioactive materials (NORM) as they emanate from earth’s crust. Also, concentrations of NORM in rocks depend on factors such as rock type and geographical origination of the rock. To understand levels of these NORM concentrations, specifically K-40 concentration, a simple study on a specific type of fertilizer (13-13-13) was performed. K-40 activity was experimentally measured by performing gamma spectrometry using a 35% relative efficient high purity germanium detector. Also, a theoretical estimation of K-40 concentration in 13-13-13 fertilizers was performed. Lastly, the measured and theoretically estimated K-40 concentrations in the fertilizers considered are compared using a one-tailed t-test at 95% confidence level. Obtained results suggest that the measured and estimated K-40 radioactivity concentrations in 13-13-13 fertilizers considered in this study are not significantly different.
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P. Poster
Estimation of Radioactivity Levels in Soilless Growth Media Collected from Agricultural Research Site in Quincy, Florida. GK Osei*, Florida A&M University, Tallahassee
; MD Abazinge, Florida A&M University, Tallahassee; LW Ngatia, Florida A&M University, Tallahassee; C Jagoe, Florida A&M University, Tallahassee; A Bolques, Florida A&M University, Tallahassee; MA Owens, Florida A&M University, Tallahassee; JK Billa, Alcorn State University, Lorman
Abstract: All organisms on earth are exposed to both natural and anthropogenic radiation. Research to date indicates that there are varying levels of radionuclides in agroecosystems, particularly in soil, plants and water. Biochar amended with soil have been proposed to enhance long-term atmospheric carbon sequestration and plant productivity. However, there is unknown levels of possible radionuclides (natural and anthropogenic) in soilless media with biochar amendments. Soilless media (a mixture of coir and pine bark amended with different percentages of biochar) were sampled from Florida Agricultural and Mechanical University Research and Extension Center (FAMU-REC) in Quincy, Florida, to assess possible radionuclides activities using gamma spectrometry. The mean activity concentration values for 235U, 226Ra, 23 2Th, 40K, and 137Cs found in the samples were 0.92±0.02, 3.32±0.19, 1.35±0.46, 22.1±053 and 0.36±0.04 Bq kg-1, respectively. The estimated external (Hex) and internal (Hin) radiation hazard values ranged from 0.01 to 0.02 and 0.02 to 0.04 with means of 0.02 and 0.03, respectively. From the results, the media-biochar amended sample are safer radiological growing media.
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P. Poster
Developing a more Methodical Audit Program for Non-Human Use Radioactive Material Laboratories through Clinical Inference. MJ Wutkowski*, Memorial Sloan Kettering Cancer Center
Abstract: Unlike research laboratories, Clinical Laboratories are known for a more rigid yet necessary methodology when conducting audits. Memorial Sloan Kettering Cancer Center (MSKCC) currently monitors 55 research labs that use Radioactive Materials (RAM) in Non-human use (NHU) formats. This program currently conducts internal audits of all laboratories in order to uphold Radiation Safety compliance. Clinical audits are more stringent and typically more than necessary for non-clinical locations however, their polices can be readily adapted to Radiation Safety audits. Many aspects of Radiation Safety and Clinical Safety overlap such as documentation, equipment monitoring, waste, PPE, and security. It was found that by using these standards a higher capture of infraction occurred. Results revealed that majority of infractions were one-time corrections or outstanding events. The following work demonstrates the benefits and challenges imposed when using a clinical viewpoint to monitor and inspect RAM users.
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P. Poster
Impact of Monte Carlo physics choice on out-of-field dosimetry for pencil beam scanning proton therapy KT Griffin*, National Cancer Institute
; YS Yeom, National Cancer Institute; MM Mille, National Cancer Institute; CI Lee, University of Michigan; JW Jung, East Carolina University; NE Hertel, Georgia Institute of Technology; CS Lee, National Cancer Institute
Abstract: In proton therapy, the smaller volume of directly irradiated healthy tissues compared to that of conventional photon therapy suggests patients may be at lower risk for treatment-related health effects. However, the primary proton beam produces a wide spectrum of secondary particles, most notably neutrons and gammas, which delivers undesired dose to organs outside the treatment field. Improved understanding of the out-of-field dose during proton therapy is an important input for epidemiological research. However, the processes by which high-energy protons produce secondary particles are multifaceted and uncertain. A variety of physics model packages are available within Monte Carlo radiation transport codes to simulate the stages of nuclear breakup, all producing different results. The purpose of this work was to systematically study how the choice of physics model affects secondary neutron and gamma production, and subsequently out-of-field organ dose, within a proton therapy patient. Three popular Monte Carlo simulation packages were used for radiation transport using developer-recommended physics settings: MCNP6, PHITS, and TOPAS. Total yield and double-differential production of secondary particles were compared across the three codes through proton pencil beam irradiation of a water phantom at four energies (80, 90, 100, and 110 MeV). Additionally, calculation of out-of-field organ dose was performed for test cases of intracranial irradiation using whole-body computational human phantoms. The resulting out-of-field organ doses were comparable between MCNP and TOPAS. Conversely, the results exposed a strong bias in forwardly-directed neutron production by PHITS, leading to lower out-of-field organ dose estimates compared to the other two codes. A figure of merit comparison showed, however, that PHITS performed the most efficient MC simulation – remarkably by two orders of magnitude.
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P. Poster
Creation of Scalable Vector Graphics Images for Use in Internal Dosimetry Visualizations AB Barker*, Francis Marion University
; DW Jokisch, Francis Marion University
Abstract: Computational internal dosimetry involves modeling the time-dependent distribution of radioactive material in various tissues and the calculation of energy deposition to target regions of interest. It is helpful to view the variations in activity and dose with time and location, as it provides insight on the impact of biokinetic modeling parameters and energy absorption quantities. Plotting of the activities and doses versus time has long been a useful tool for visualizing these relationships. Our work is motivated by a desire to create a heatmap visualization of these quantities in human tissue. A prerequisite for the heatmap is to create an image of a human body with source and target regions tagged and outlined. A series of scalable vector graphics (SVG) files have been created which depict the pertinent source and target regions used in internal dosimetry. These SVG files are created by two-dimensional digital image tracings (or path drawings where appropriate) of organ and tissue shapes within illustration and image-manipulation programs. The rounded shapes from source images are then converted into high resolution polygons and renamed appropriately to fairly represent each target region anatomically. Multiple files of human diagrams have been created to account for biological sex and different body systems. These image files can be coupled to internal dosimetry data to create visualizations of the movement of radioactive material through the body and tissue-dependence of radiation dose.
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P. Poster
Use of Radioiodine Bioassay in a Comprehensive Cancer Center DJ Chiappetta*, Memorial Sloan Kettering Cancer Center, New York
Abstract: Regulation, license condition and professional responsibility for worker protection compel the use of bioassay in monitoring for internal exposure to radioactive materials. Radioiodines, particularly I-131, are widely used in the treatment of thyroid cancer and as a targeted therapeutic payload in antibody therapies. The volatility of radioiodine and subsequent risk of intake from handling these sources is well documented and warrants special attention from a Health Physics perspective. At Memorial Sloan Kettering Cancer Center in New York City, widespread radioiodine use in both the laboratory and clinical settings requires a dedicated program for monitoring the effectiveness of procedural and engineering controls. At our institution in 2019 alone, 284 patients were treated with various I-131 therapies using activities ranging from 259MBq to 35.5GBq (7 to 959mCi), primarily in capsule, sealed form or pre-labeled to a targeted molecule with low potential for volatility. Inhouse radiolabeling of I-131 for antibody therapy performed by radiopharmacists and clinical and research radiochemists represents the bulk of work done with elemental radioiodine at our institution. We present the evaluation of our homegrown equipment setup and characterization of its capabilities, our methods for determining desired frequency of bioassay for various chemical forms and isotopes of radioiodine, our rationale for deciding which staff requires routine bioassay, and strategies for encouraging participation in our radioiodine bioassay program.
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P. Poster
Estimation of Skin Dose Rate Contamination from I-131 Therapy Patients A Willis, Texas A&M University
; S Adadi*, Texas A&M University; S Dewji, Texas A&M University
Abstract: Alexus Willis1, Sherry Adadi1 , Shaheen Dewji1
1 Department of Nuclear Engineering, Texas A&M University
One of the general uses of Iodine-131 in the medical field is for diagnosing and treating patients with hyperthyroidism and differentiated thyroid cancer through administration of Iodine-131. After the Iodine-131 is administered, the patients sometimes reside at a hotel to avoid exposing their families and close ones to hazardous radiation. This study's primary purpose was to estimate two different exposure scenarios, including (1) the skin dose from I-131 excretion due to perspiration and voiding in the event patients have self-reabsorption; and (2) the dose rate to hotel workers/caregivers when cleaning contaminated surfaces. The dose rate for both cases was obtained using VARSKIN software. VARSKIN is a computer code and an algorithm to calculate skin dose from radioactive skin contamination. Skin dose rates were measured and estimated five days after receiving the I-131 dose for self-reabsorption and surface contamination scenarios. Furthermore, the skin dose from I-131 was compared between hyperthyroidism and cancer patients.
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P. Poster
Cells' Biological Response to Galactic Cosmic Rays using Neutron Irradiation VI Irvin*, Georgia Institute of Technology
Abstract: Radiation dose to astronauts is a significant concern for exploration of space beyond the earth. Radiation of all types is present in space in increased amounts compared to Earth. Each source brings its own concerns and dangers for potential human health. For example, galactic cosmic rays (GCR) are present everywhere in the universe and consist of high energy charged particles. Solar flares can create protons emanating from the sun. Of concern to the study of the health effects from this high energy space radiation is the track structure, density of energy, and charge deposited per unit distance in the organs of the astronauts. This is described by a quantity known as Linear Energy Transfer (LET). Georgia Tech is looking at available neutron sources that might be used to generate LET spectra that cover the same LET range as GCR.
The effort reported will be the results of irradiating biological samples prepared by our collaborators at Emory University with neutron sources at Georgia Tech. This effort required a sample transfer mechanism and permissions were obtained so the samples could be transferred to and from Emory and Georgia Tech. The construction of a sample irradiation system and the experimental determination of the LET spectra in the neutron fields used at Georgia Tech will be presented. The results will include the scoring of the biological samples after irradiation with neutrons. The results will be further related to estimates of the LET distributions of charged particles generated in the samples by neutron interactions. This involves the staining of gamma H2AX to visualize the radiation tracks in cancer cell lines such as HCT 116 colon cancer.
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TLD Sensitivity Analysis for Improvement of Dose Reconstructions for the Department of Energy Radiation Exposure Monitoring System S Dalak*, Department of Nuclear Engineering, Texas A&M University
; RH Mendleski, Department of Nuclear Engineering, Texas A&M University; M Hiller, Independent Researcher; A Golden, Oak Ridge Associated Universities; SA Dewji, Department of Nuclear Engineering, Texas A&M University; A Kalinowski, Department of Nuclear Engineering, Texas A&M University
Abstract: The Department of Energy keeps ongoing records of all badged radiation workers within their system, reporting the effective dose values to Oak Ridge Associated Universities annually to be input to the Radiation Exposure Monitoring System (REMS). This system, containing dose records for over 500,000 unique workers, provides a wealth of information for dose reconstruction and epidemiological study. However, with the doses reported in effective dose, it is essential that the doses be converted back to absorbed dose in the case of epidemiology studies. This requires a dose reconstruction, using the REMS data to formulate the source term. This data is collected via TLD badge, ring and ankle monitors, and occasionally eye monitors. To ensure the most reliable information for the epidemiology studies, the bounding range of variables in reconstructing source terms and receptor (worker) must be adequately defined. The assumption is made that all workers wear their badges around their neck, centered on their sternum with the windows facing out. However, it is essential to analyse the effects of varying position of TLD on a human, in the event the badge is worn incorrectly. Thus, a sensitivity analysis using PIMAL phantoms and MCNP has been done to determine how varying position of these TLDs effects the recorded TLD values, which can then be used to further inform REMS reconstructions.
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