Health Phys. Abstracts,Volume 126,Number 2
Statistical Analysis of Radioactivity: Lamprecht Uranium Mine in Texas
Mark C. Harvey1 and Nancy L. Glenn Griesinger2
(1. Department of Physics, Texas Southern University, Houston, TX 77004;2. Department of Mathematical Sciences, Texas Southern University, Houston, TX 77004)
Abstract:The former Lamprecht uranium mine facility in Texas ceased operations well before the new millennium. However,decommissioning activities were never completed by the licensee. Consequently, a legal proceeding was authorized between stateand licensee representatives. Meanwhile, state funds were used to hire an independent contractor to perform radiological surveysand assess the magnitude of residual radioactivity across the terrain at the site. The purpose of this study was to apply advancedspatial statistical methods to the survey data measured by contractors at the Lamprecht site to precisely predict remaining radioactivehotspot locations post soil remediation activities. To accomplish this, descriptive statistics such as Google maps and boxplots alongwith inferential spatial statistical techniques, e. g. , kriging and semivariograms, were employed. Rcoding was also used throughout. Specifically, the descriptive statistical methods included geographical mapping of targeted areas at the site coupled withsummary statistics. Inferentially, spatial analytical techniques were employed to pinpoint the locations of elevated radiation levelsabove regulatory limits. Our results suggest that fewer hotspots were identified after remediation activities were completed at thesite. This study provides an additional analytical resource for the State of Texas regarding the release of this former in situ leachuranium mine site to landowners for unrestricted use.
Key words: analysis; statistical; contamination; environmental; environmental impact; radium
Health Phys. 126(2):65-78; 2024
Enhancing Precision in L-band Electron Paramagnetic Resonance Tooth Dosimetry: Incorporating Digital Image Processing and Radiation Therapy Plans for Geometric Correction
Jong In Park1 , Chang Uk Koo2 , Jeonghun Oh2 , In Jung Kim1 , Kwon Choi2 , Sung-Joon Ye2,3,4,5
(1. Korea Research Institute of Standards and Science, 267 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea;2. Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Scienceand Technology, Seoul National University, Seoul, 08826, Republic of Korea;3. Department of Applied Bioengineering, Graduate School of Convergence Science and Technology, Seoul National University,Seoul 08826, Republic of Korea;4. Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea;5. Advanced Institutes of Convergence Technology, Seoul National University, 16229, Suwon, Republic of Korea)
Abstract:Following unforeseen exposure to radiation, quick dose determination is essential to prioritize potential patients thatrequire immediate medical care. L-band electron paramagnetic resonance tooth dosimetry can be efficiently used for rapid triage asthis poses no harm to the human incisor, although geometric variations among human teeth may hinder accurate dose estimation.Consequently, we propose a practical geometric correction method using a mobile phone camera. Donated human incisors wereirradiated with calibrated 6 MV photon beam irradiation, and dose-response curves were developed by irradiation with apredetermined dose using custom-made poly(methyl methacrylate) slab phantoms. Three radiation treatment plans for incisors wereselected and altered to suit the head phantom. The mean doses on tooth structures were calculated using a commercial treatmentplanning system, and the electron paramagnetic resonance signals of the incisors were measured. The enamel area was computedfrom camera-acquired tooth images. The relative standard uncertainty was rigorously estimated both with and without geometriccorrection. The effects on the electron paramagnetic resonance signal caused by axial and rotational movements of tooth sampleswere evaluated through finite element analysis. The mean absolute deviations of mean doses both with and without geometriccorrection showed marginal improvement. The average relative differences without and with geometric correction significantlydecreased from 21. 0% to 16. 8% (p = 0. 01). The geometric correction method shows potential in improving dose precisionmeasurement with minimal delay. Furthermore, our findings demonstrated the viability of using treatment planning system doses indose estimation for L-band electron paramagnetic resonance tooth dosimetry.
Key words: emergencies; radiological; dosimetry; modeling; dose assessment; radiation dose
Health Phys. 126(2):79-95; 2024
Simple Moving Average Applied to “ISO Method” CPAM Concentration Estimates: An Unexpected Result
William C. Evans1
(1. Germantown,MD 11019 Grassy Knoll Terrace, Germantown,MD 20876)
Abstract:A surprisingly large amount of variance reduction has been observed when filtering International Organization forStandardization (ISO) “ISO Method” continuous particulate air monitor (CPAM) airborne radioactivity concentration estimateswith a simple three-point moving average. This processing has relatively little lag relative to the amount of variance reductionobtained. The key factor producing this effect is the specific autocorrelation structure of the estimated concentrations, which arebased on taking first differences of integrated-count data; this scheme results in successive count differences that contain a common count value between them. The observed variance reduction factor has also been derived analytically.
Key words: air sampling; monitoring; air; safety standards; radioactivity; airborne
Health Phys. 126(2):96-98; 2024
Measurement of 238 U, 232 Th, 222 Rn and 220 Rn Contents in Optical Contact Lenses: Resulting Alpha and Beta Equivalent Doses to the Eye Tissues of Adult Patients
M. A. Misdaq1 and B. Elouardi1
(1. Nuclear Physics and Techniques Laboratory, Department of Physics, Faculty of Sciences Semlalia, BP. 2390, University ofCadi Ayyad, Marrakech, Morocco)
Abstract:To estimate equivalent doses received by eye tissues of patients, contents of uranium (238 U), thorium (232 Th), radon(222 Rn), and thoron (220 Rn) were determined inside various optical contact lenses used for vision correction. 238 U, 232 Th, 222 Rn,and 220 Rn contents varied between (3. 44 ± 0. 24) mBq kg-1 and (18. 3 ± 1. 28) mBq kg-1 , (0. 57 ± 0. 04) mBq kg-1 and(3. 53 ± 0. 25) mBq kg-1 , (3. 44 ± 0. 24) mBq kg-1 and (18. 3 ± 1. 28) mBq kg-1 , and (0. 57 ± 0. 04) mBq kg-1 and(3. 53 ± 0. 25) mBq kg-1 , respectively. New external dosimetric models, depending on the cornea eye surface of patients, 238 U,232 Th, and 222 Rn concentrations inside optical contact lenses, half-life of the emitting radionuclides, and exposure time of patients,have been developed. It has been shown that alpha-particles emitted by the 238 U and 232 Th series inside the studied optical lensestransfer their energies essentially to the cornea tissues whereas the emitted beta-particles may reach and lose their energies in thecrystalline lens of eyes of patients. Alpha-equivalent doses received by eye tissues of patients due to the diffusion of 222 Rn and 220 Rngases presentin the considered opticallenses were determined. The higher value of the total (alpha plus beta) equivalent dose to theleft and right eyes of adult patients wearing optical contact lenses (14 hours per day) has been found equal to 1. 32 mSv y-1 cm -2 .It is recommended for patients to reduce the wearing period of optical contact lenses to reduce eye disease risks such as cataract.
Key words: operational topics; analysis; risk; dosimetry; radon
Health Phys. 126(2):104-116; 2024
Introducing DEPDOSE, a Tool to Calculate Dose Coefficients to Members of the Public for Radioactive Aerosols
John Klumpp1 , Luiz Bertelli1 , Keith Eckerman1 , Matthew Nelson1 , Liam Wedell1 , Mina Deshler1 , Sara Brambilla1 ,Michael Brown1
(1. Los Alamos National Laboratory, Los Alamos, NM)
Abstract:This paper presents DEPDOSE, an open-source computer application that combines the KDEP respiratory tract depositionfractions for inhaled aerosols with DC_PAK committed equivalent dose coefficients for a unit deposition in each region of therespiratory tract. DEPDOSE allows the user to rapidly produce tables of dose coefficients for workers and members of the publicinhaling precisely defined, user-specified aerosols using the ICRP Publication 60 methodology. Combined with a plume dispersionmodeling system, such as the Quick Urban & Industrial Complex (QUIC) Dispersion Modeling System, this makes it possible topredict radiation doses downstream from an accidental or intentional release of radioactive materials. For this work, a radioactiveplume was calculated to members of the public downstream from a dirty bomb in Chicago. DEPDOSE is published under an opensource license, and can be downloaded at https:/ / github. com/ lanl/ DEPDOSE.
Key words: operational topics; aerosols; dose assessment; International Commission on Radiological Protection (ICRP)
Health Phys. 126 (2):117-121; 2024