Health physics最新文献

Introduction: This research explores the application of advanced geostatistical methods to predict the locations of residual radioactive hotspots at the former Zamzow uranium mine site, located near Three Rivers, TX. The site, part of the broader Lamprecht-Zamzow project, has a complex history, having undergone in situ uranium mining and processing, followed by decommissioning activities. The role of this study is not to set or recommend remediation goals, as this responsibility lies with the State of Texas. Rather, the purpose of the statistical analyses in this work is to present the data objectively, predicting potential contamination at unsampled locations and where further actions may be needed. Importantly, the findings of this study aim to inform state regulators regarding the unrestricted release of the site for landowner use, providing critical insights into the effectiveness of previous remediation efforts. By employing rigorous geostatistical techniques on survey data collected by environmental services contractors, this study models the spatial distribution of contamination referred to as "hotspots" with precision. This research marks an important advancement toward a scientifically grounded, objective approach in assessing radioactive site remediation and informing future decisions regarding site decommissioning and land restoration at former uranium sites. Importantly, the statistical analysis in this work demonstrated a clear reduction in the number of hotspots after site remediation, highlighting the effectiveness of the intervention.

Effective decision-making in a nuclear emergency is an essential element of achieving the goals of Emergency Preparedness and Response (EPR). Within the International Atomic Energy Agency's (IAEA) General Safety Requirements (GSR) Part 7, preparedness goals are stated generally as having adequate capabilities in place for an effective response. Past nuclear accident experience has demonstrated the complexities involved in urgent and early phase protective action decision-making which is characterized by a distinct lack of information resulting in poor or inappropriate decisions that do more harm than good. The Operational Planning Process (OPP) has been developed by many professional militaries around the world as a means of dealing with equally complex situations. In this work we explore a component of the OPP, wargaming, and apply it to the preparedness phase of a nuclear emergency to validate response planning. The work demonstrates the usefulness of the activity at improving urgent and early phase decision-making and decision-making tool development. The concept effectively addresses several lessons learned from past nuclear incidents as well as continued observations calling for improved tools to better integrate a scientific and technical understanding into a justified and optimised, all hazards emergency response environment.

On June 9 th and 10 th , 2025 the Health Physics Society (HPS) and National Council on Radiation Protection and Measurements (NCRP) jointly sponsored two open forums with the hopes of discussing and responding to constituent beliefs regarding a series of nuclear-related Executive Orders (EOs). The HPS and NCRP leaders were joined by members from the American Academy of Physicists in Medicine (AAPM), and the Conference of Radiation Control Program Directors (CRCPD) as panelists to help respond and moderate the forums. The forums focused on three of the nine relevant EOs, and, while varying opinions were shared, three common themes were strongly supported: First, many of the constituents support change, particularly regulatory harmonization (205/212, 97%), and the time to make changes [now] is appropriate due to these EOs. Second, the constituents believe that these EOs will have a significant impact on the nuclear fields (420/468, 90%). Third, the constituents strongly support the United States in increasing its use of nuclear power (236/245, 96%).

An accurate internal dosimetry is important in 131I radionuclide therapy. In patients who have undergone a thyroidectomy, organs other than the thyroid absorb higher doses as the radionuclide is transported through the body because most of the thyroid gland is removed, and it cannot retain the 131I. The primary objective of this study is to compare the absorbed doses in at-risk organs due to intake of 131I after thyroidectomy vs. a healthy thyroid scenario. The biokinetic model of internal dosimetry for healthy thyroid as proposed by the International Commission on Radiological Protection (ICRP) in Publication 137 and a radiation transport simulation in Monte Carlo N-Particle 6 (MCNP6) were used. From the biokinetic model, average activities of 131I over a 30 h period were obtained, and these activities were used as source terms in MCNP6 simulations transporting gamma rays and beta particles to estimate absorbed doses in at-risk organs. The use of average activities is a new approach proposed in this study. Once the internal dosimetry model for a healthy thyroid was complete and functional, it was adapted for the scenario following thyroidectomy. This involved changing the transfer coefficients connected with the thyroid in the biokinetic model to constants proposed by Taprogge et al. in 2021. With this adjusted model, average activities of 131I over a 30-h period were obtained again and used as source terms in MCNP6 simulations of a patient following thyroidectomy, and from this simulation, absorbed doses in at-risk organs were estimated. These coefficients had not been used to estimate organ doses using MCNP. The 131I activity in the thyroid gland was found to be 20.4% of the initial administered dose in the scenario with a healthy thyroid vs. 0.64% following thyroidectomy. After thyroidectomy, all organs other than the thyroid absorbed higher radiation doses compared to the scenario with a healthy thyroid. The results of this study allow comparison of the absorbed doses between the scenarios of a healthy thyroid and after thyroidectomy, showing substantial differences between the modeled scenarios, which underscores the need to consider the larger context when assessing radiological impact on at-risk organs during 131I therapy.

Accurate assessment of external radiation dose rates from 137 Cs is essential for evaluating radiological risk in environmental and occupational settings. This study refines dose conversion coefficient calculations by incorporating depth-dependent soil density and addressing limitations in conventional methods that assume constant soil density. We calculated dose conversion coefficients for 137 Cs in soil, considering both exponential and Gaussian distributions of activity concentration. Using two models, one with constant density and another with variable density as a function of depth, we compared dose rates to quantify the effect of soil density variations. Results indicate that dose rates are consistently higher when depth-dependent density is applied. The effect is more pronounced when 137 Cs activity is distributed over larger depths (i.e., greater relaxation lengths) or when broader Gaussian distributions are considered. This suggests that assuming constant soil density may lead to underestimations of dose rates, especially in heterogeneous or compacted soils. Our findings emphasize the importance of accounting for density variability in dose calculations to enhance radiological risk assessments for areas contaminated with 137 Cs.

Testicular radiation exposure has been linked to diminished spermatogenesis, male infertility, and potentially testicular cancer. Despite this, the risk of testicular exposure from intraoperative fluoroscopy to the male orthopedic surgeon has yet to be studied. The purpose of this study is to determine factors associated with unnecessary testicular radiation exposure in male orthopedic surgeons. The study was designed to answer the following questions: (1) Do the designs of lead apron protection result in any differential testicular radiation exposure? (2) Does the position of the surgeon (standing, sitting, and knee position while sitting) alter the amount of testicular radiation exposure? (3) Does any combination of lead apron design and surgeon positioning increase the degree of testicular radiation exposure? A life-sized, whole-body, anthropomorphic phantom simulating an orthopedic surgeon was positioned adjacent to a hand table attached to a standard radiolucent operating table. A digital dosimeter was attached to the groin region beneath a lead apron. Scatter radiation dose equivalent rates were measured during continuous anteroposterior C-arm fluoroscopy of a forearm/hand phantom. Four trials were conducted using three different types of protective lead aprons (cross-back, full-skirt, and half-skirt) in three different positions (standing, sitting with knees 10 cm apart, and sitting with knees 25 cm apart). Radiation dose-equivalent rates were compared using the Student's t-test and analysis of variance. No scatter radiation (measured value of 0.0 mrem min -1 [0.0 Sv min -1 ]; below minimum detectability of dosimeter) was detected underneath the lead aprons in the standing position and when sitting with the knees 25 cm apart, using all three types of lead. When sitting with the knees 10 cm apart, the mean dose equivalent rate of scatter radiation was higher using the half-skirt (0.01 mrem min -1 [0.000001 Sv min -1 ]) than the cross-back (below minimum detectability of dosimeter) and skirt aprons (below minimum detectability of dosimeter), but this did not reach statistical significance (p = 0.44). For all apron types and all positions, the use of an apron resulted in significantly less scatter radiation exposure when compared to no protection (p < 0.001). Protective lead aprons are effective at preventing testicular radiation exposure in both the standing and sitting positions. As the only detectable radiation exposure occurred with use of a half-skirt apron when sitting with the knees spread 10 cm apart, cross-back and full-skirt aprons may provide slightly enhanced protection over half-skirt aprons in the sitting position.

Iodine-131 ( 131 I) is a common therapy for treatment of differentiated thyroid carcinoma (DTC); however, its radioactivity poses a radiation safety risk to public health. There is inter-facility variation in release instructions to minimize incident exposure to other individuals. Isolation measures are not without harm. Most studies on this topic rely upon cumulative dosimetry to measure exposure, but this does not provide the researcher with critical dose protraction information. Refining estimation of elimination kinetics with more frequent exposure readings would help optimize radiation safety recommendations. Measuring radiation exposure from patients with DTC post-thyroidectomy receiving 131 I would better quantify its elimination kinetics to improve radiation safety recommendations. Patients with DTC post-thyroidectomy undergoing radioiodine remnant ablation with 131 I were instructed to measure exposure at a distance of 1 m, three times a day for 14 d, using an ion chamber at home. These data were used to form an exponential decay model and estimate the time after which cumulative exposure is below a reasonably low threshold. The average effective half-life was 15.8 h when calculated using real-time exposure readings from 32 patients. Among patients administered less than 4.22 GBq, cumulative effective dose is ≤1 mSv after 24 h of isolation. Between 4.22 and 6.03 GBq, cumulative effective dose is ≤1mSv after 48 h of isolation. Cumulative gamma radiation exposure at 1 m remains low enough to consider re-evaluating isolation protocols that encourage long-term distancing past the first 24 h in post-thyroidectomy patients treated with 131I for remnant ablation.

pyDOSEIA is a Python package designed for meteorological data processing and radiological impact assessment in diverse scenarios, including nuclear and radiological accidents. Built upon robust computational models and using modern programming techniques, pyDOSEIA employs the Gaussian Plume Model and follows IAEA and AERB guidelines, offering a comprehensive suite of tools for estimating radiation doses from various exposure pathways, including inhalation, ingestion, groundshine, submersion, and plumeshine. The package enables age-specific, distance-specific, and radionuclide-specific radiation dose computations, providing accurate and reliable calculations for both short-term and long-term exposures. Additionally, pyDOSEIA leverages up-to-date dose conversion factors, features parallel processing capabilities for rapid analysis of large datasets, and facilitates applications in machine learning and deep learning research. With its user-friendly interface and extensive documentation, pyDOSEIA empowers researchers, practitioners, and policymakers to assess radiation risks effectively, aiding in decision making and emergency preparedness efforts. The package is open-source and available on GitHub at https://github.com/BiswajitSadhu/pyDOSEIA .

This study focuses on recent advancements in biodosimetry using continuous wave (CW) Q-band electron paramagnetic resonance (EPR) spectroscopy and mini-biopsy samples from tooth enamel. When radiation is absorbed, the carbonate impurities in enamel (i.e., hydroxyapatite) are changed into •CO2- (carbon dioxide radical anions), which become trapped within the crystal lattice and remain stable for durations far exceeding human lifespans. This stability makes tooth enamel an ideal material for assessing radiation doses in both accident and retrospective scenarios. In contrast to traditional, more invasive CW X-band EPR (9.8 GHz) methods, the CW Q-band EPR technique allows for the non-invasive (or minimally invasive) collection of smaller enamel fragments. This enables faster, more comfortable sampling. Operating at approximately 34 GHz, CW Q-band EPR offers enhanced sensitivity and a significantly improved signal to noise ratio (S/N) compared to CW X-band EPR. This increased sensitivity is crucial for detecting lower radiation doses in smaller samples, making it particularly useful for accurately identifying high-risk individuals in radiation triage situations. For this study, mini biopsies weighing around 2 mg were extracted from teeth and analyzed at room temperature using CW Q-band EPR. Calibration curves were established using reference doses, allowing the precise calculation of doses from signal intensity. Radiation doses higher than 100 mSv were estimated with high precision and accuracy. The combination of CW Q-band EPR spectroscopy and mini-biopsy sampling of tooth enamel provides a rapid, reliable method for dose assessment in radiation triage scenarios. This advancement is essential for developing efficient biodosimetry techniques, enabling the timely identification and management of individuals exposed to ionizing radiation during radiation incidents. Additionally, this method proves invaluable for retrospective dose reconstruction in cases of chronic exposure applicable to individuals, groups, or entire populations.