Health physics最新文献

Abstract: In the optimization of radioactive waste disposal facility design, it is important to compare multiple facility design options with the aim of reducing the effective dose as low as reasonably achievable. In this study, a methodology for optimizing the facility design using a probabilistic approach was proposed, and two case studies were provided the application of the methodology and interpretation of the dose distributions. This methodology incorporates the time integration of the 95th percentile value and the sum of coefficients of variation extracted from the probability distribution of dose profile over time as the indicators for relative comparison on the optimization. This methodology enables consideration of the dose with uncertainty for the entire long-term assessment period in the optimization. This allows a more multifaceted comparison of options and is expected to improve the ability to explain optimization with the consideration of long-term uncertainty. While various factors including economic, social, and possibly others are relevant to the decision process, this study focuses on the dose estimations as an indicator for optimization. In the case studies, intermediate-depth disposal in Japan, which is one of the disposal systems of low-level radioactive waste, is used as an example and the groundwater release scenario was the focus. The comparison of multiple options in low-diffusivity and low-permeability layers were assumed. These are the important factors in the migration of radioactive nuclides, while other parameters can also be considered in optimization by using the proposed methodology.

Abstract: The objective of this paper is to derive basic restrictions for induced internal electric field and reference levels for external magnetic flux density for a class of periodic non-sinusoidal waveforms as multiples of the existing limits applicable to sinusoidal waveforms in current exposure standards. The Law of Electrostimulation and the Spatially Extended Nonlinear Node computational model were used to derive peripheral nerve stimulation thresholds of the internal electric field for both non-sinusoidal and sinusoidal waveforms. Threshold ratios (non-sinusoidal to sinusoidal) permitted basic restrictions and reference levels to be derived as multiples of the sinusoidal ones. Intercomparisons of threshold ratios from both models suggest that they are in agreement for flat-topped flux density waveforms with fast rise-times relative to the period but showed a discrepancy for the continuous sinusoid. Results from the computational model were used to establish the threshold ratios used in the conversion. Resulting non-sinusoidal basic restrictions and reference levels were found to have the same functional relationship with frequency as the sinusoidal ones, consisting of two ranges: a flat rheobase and a frequency-dependent (basic restriction) or inverse frequency-dependent (reference level) portion that intersects the rheobase at a transition frequency that is waveform-dependent. Above the transition frequency, the non-sinusoidal basic restriction was found to be inversely related to the flux density rise-time, resulting in an increased limit for fast-rising waveforms. The transition frequencies of fast-rising waveforms were found to be lowered relative to the sinusoidal one. Above the same transition frequency, the non-sinusoidal reference level is flat with frequency and was found to be approximately 79% lower than the sinusoidal one.

Abstract: Considering workers in interventional radiology occupationally exposed to relatively higher radiation dose, it is imperative to reasonably and reliably assess the occupational exposure of these workers. This paper presents a method to evaluate the occupational exposure to the interventional radiology workers monitored by using two personal dosimeters, based on data from 115,997 workers collected by the Chinese Registry of Radiation Workers in China during the period 2015-2021. It was observed that only 17.7% (20,572 in 115,997) of interventional radiology staff had a meaningful measurable result. The scatter plot of Hp(10)over-Hp(10)under vs. Hp(10)over was obtained to classify between the proper use group and misuse group. In addition, it was found that the effective dose calculated using the single-dosimeter approach proposed by Martin and Magee was close to those obtained using two other double-dosimeter approaches. Furthermore, the Swiss ordinance algorithm was chosen to assess the occupational exposure as a conservative estimation method. Meanwhile, it was also found that the average annual effective dose in tertiary hospitals is significantly higher than that in secondary hospitals in China (Z = -2.491, p < 0.05/3 = 0.017). Based on these observations, rigorous surveillance, quality control measures, and better workload management are still necessary to correctly evaluate the occupational exposure of interventional radiology staff. Our results are expected to provide a feasible and accurate method for the evaluation of occupational radiation dose to interventional radiology staff wearing two personal dosimeters and contribute to effective prevention and control of radiation health risks.

Abstract: Internal dosimetrists are concerned with the development, selection, and calibration of biokinetic models to calculate radiation doses from incorporated radionuclides. This is accomplished using measurements of radionuclides in organs, tissues, and excreta, i.e., bioassay measurements. Each bioassay measurement has a corresponding likelihood function, which represents the relative likelihood of different biokinetic model parameters resulting in the measurement value. In order for a bioassay measurement to be interpreted properly, the correct likelihood function must be determined. Failing to use the correct likelihood function for each bioassay measurement results in improperly weighting certain measurements over other measurements, which in turn leads to incorrect dose estimates. This paper describes the correct likelihood functions to use for a wide variety of bioassay measurements, as well as a description of how to use them. These likelihood functions represent the vast majority of those likely to be needed for interpreting bioassay measurements. Therefore, this paper may serve as a tool kit that can be used by academic and occupational internal dosimetrists.

Abstract: This study aims to assess the residual radioactivity produced in the human head phantom following irradiation from a boron neutron capture therapy neutron source based on a 2.8 MeV proton accelerator. Using Monte Carlo software to simulate irradiation on a head phantom based on ICRP Publication 110, it was found that, in addition to the nuclides 24Na, 38Cl, and 42K reported in other literature, 32P is the nuclide that contributes the most to the internal exposure dose in patients post-BNCT. Calculations indicate that the effective dose resulting from 60 min of irradiation activation ranges between 148 and 401 μSv, which is relatively low. This study also analyzed the dose rate at a distance of 60 cm from the activated head. Approximately 5 min after irradiation ends, short-lived nuclides such as 19O and 20F decay completely, reducing the dose rate to below 1 μSv h-1. Although nuclides like 24Na will continue to emit radiation, the dose rate remains at a safe level.

Abstract: Background: In operating theatres, diagnostic radiography is used to capture images during surgical operations. With the growing use of fluoroscopy, there are concerns about increased radiation exposure to healthcare workers such as doctors and nurses. Thus, assessing HCWs' knowledge and adherence to radiation protection is crucial to prevent overexposure, radiation-related health issues, and ensure patient safety. Objective: The study aimed to assess the knowledge of non-radiation HCWs regarding radiation protection and determine the level of adherence to radiation protection in two theaters. Methods: A quantitative descriptive research methodology was used. Data collection involved a questionnaire, and participants were selected through a simple random sampling method. Data were analyzed using SPSS version 26. Results: Fifty-eight non-radiation HCWs participated. Most (77.6%) were female with nurses comprising the largest demographic (62.1%). Most participants (53.4%) lacked prior education in radiation protection. Concerningly, 70.7% did not use dosimeters during theater radiography, which is a requirement for radiation protection. No significant association was found between participants' allocated hospital and the level of knowledge, but a significant association (p = 0.027) was found between participants' allocated hospital and adherence levels. Conclusion: The findings suggest inadequate knowledge and adherence to radiation protection. Therefore, education on radiation protection must be mandated, and measures should be taken to enforce adherence.

Abstract: Using archival peripheral blood slides from radiation accident patients, we have recently described the pseudo-Pelger Huët anomaly (PPHA) in neutrophils as a new radiation-induced biomarker, useful for dosimetry not only immediately after a radiation incident but also potentially helpful as a tool in retrospective dosimetry. In conjunction with the Radiation Accident Registry at the Radiation Emergency Assistance Center/Training Site (REAC/TS), the frequency of PPHA cells has been compared from selected patients in the Y-12 criticality accident in Oak Ridge, TN, in 1958 and from the patient in the 1971 60 Co accident at the USAEC Comparative Animal Research Laboratory (CARL), also in Oak Ridge. Patients A, C, and D in the Y-12 accident are described as having an average dose of 2.53 ± 0.14 Gy gamma + 0.90 ± 0.05 Gy neutron, while the patient in the CARL event had 2.6 Gy gamma dose from event reconstruction. Since the average gamma energies are almost identical in these two cohorts, it is possible to estimate the deterministic neutron relative biological effectiveness (RBE d ) for PPHA formation in a criticality event. The neutron RBE d calculated in this way is an average value over the neutron fission energy spectrum and is found to be 3.4 ± 0.6, in good agreement with the currently recommended value of 3 for acute neutron dose to red marrow.

Abstract: In the last 30 y, observational as well as experimental studies have addressed possible health effects of exposure to radiofrequency electromagnetic fields (EMF) and investigated potential interaction mechanisms. The main goal of ICNIRP is to protect people and the environment from detrimental exposure to all forms of non-ionizing radiation (NIR), providing advice and guidance by developing and disseminating exposure guidelines based on the available scientific research on specific parts of the electromagnetic spectrum. During the development of International Commission on Non-Ionizing Radiation Protection's (ICNIRP's) 2020 radiofrequency EMF guidelines some gaps in the available data were identified. To encourage further research into knowledge gaps in research that would, if addressed, assist ICNIRP in further developing guidelines and setting revised recommendations on limiting exposure, data gaps that were identified during the development of the 2020 radiofrequency EMF guidelines, in conjunction with subsequent consideration of the literature, are described in this Statement. Note that this process and resultant recommendations were not intended to duplicate more traditional research agendas, whose focus is on extending knowledge in this area more generally but was tightly focused on identifying the highest data gap priorities for guidelines development more specifically. The result of this distinction is that the present data gap recommendations do not include some gaps in the literature that in principle could be relevant to radiofrequency EMF health, but which were excluded because either the link between exposure and endpoint, or the link between endpoint and health, was not supported sufficiently by the literature. The evaluation of these research areas identified the following data gaps: (1) Issues concerning relations between radiofrequency EMF exposure and heat-induced pain; (2) Clarification of the relation between whole-body exposure and core temperature rise from 100 kHz to 300 GHz, as a function of exposure duration and combined EMF exposures; (3) Adverse effect thresholds and thermal dosimetry for a range of ocular structures; (4) Pain thresholds for contact currents under a range of exposure scenarios, including associated dosimetry; and (5) A range of additional dosimetry studies to both support future research, and also to improve the application of radiofrequency EMF exposure restrictions in future guidelines.

Abstract: Rapidly identifying individuals who have received internal radiation exposure above action guidelines is crucial for mitigating health risks and addressing public concerns immediately following a radiological event involving the dispersal of radioactive materials. This study describes a novel triage method using a conventional Geiger-Mueller (GM) detector to select those individuals from the large group of persons who may have received an intake of radioactive material at levels corresponding to one Clinical Decision Guide (CDG). The triage method involves placing a portable GM detector against the lower anterior torso of a sitting person as they bend over to surround the detector with their body. The response of the GM detector is evaluated using a new, specially designed anthropometric phantom that simulates combined tissues of the lower thorax and gastrointestinal (GI) tract and is fabricated with a tissue substitute material that matches the overall radiological properties of human tissue present in this body region. The phantom has four separate layers of tissue substitute material with ports to accommodate a single GM detector at the center and one or more sealed radioactive sources that can be arranged to characterize the detector response for a variety of source distributions, including a "hot spot." In this study, the response of a Ludlum Model 133-4 GM detector was evaluated using sealed sources of 232 Th and 137 Cs to determine the measurement efficiency for a quantity of activity present in the abdomen within a few hours post-intake equivalent to 1 CDG. Results demonstrate that the Quick Sort triage procedure using a single GM detector placed against the abdomen of a person can reliably detect internal deposition resulting from an intake equivalent to 1 CDG for 232 Th or a significantly lower activity of 137 Cs within a few hours following a radiological incident. The evaluation was performed over a wide range of photon energies, so the Quick Sort triage procedure is expected to be suitable for most fission products distributed uniformly within the abdomen or as a single "hot spot."

Abstract: This paper offers a comprehensive exploration of the future trajectory of health physics, examining influential factors in external and internal dimensions. External factors include an in-depth analysis of low-dose (10-100 mSv) measurement challenges and priorities, highlighting the transformative potential of biomarkers in solving radiation susceptibility following low-dose exposures. Cutting-edge technologies are at the forefront, with insights into emerging radiation detection tools like plastic scintillators with triple discrimination capabilities and sensors based on plastic scintillation microspheres (PSm) for estimating α and β emitting radionuclides in environmental samples. Remote detection systems using drones, robot dogs, and quantum sensors boasting heightened sensitivity and precision also are discussed. Integrating artificial intelligence (AI) and data analytics emerges as a pivotal element, promising to redefine health physics by minimizing radiation exposure risks. The exploration includes innovative materials for radiation shielding, advancements in virtual reality applications, preparation for radiological protection during armed conflicts, and the ever-evolving landscape of decommissioning health physics. Examining health effects from non-ionizing radiation and analyzing broader contextual factors such as regulatory shifts, geopolitics, and socioeconomic influences adds depth to understanding the external forces leading to the future of health physics. Internally, the paper focuses on the transformative dynamics of health physics education and training, encompassing expanded educational horizons, innovative delivery methods, targeted student outreach strategies, and insights into navigating health physics careers amid a dynamically evolving job market. The discussion unfolds further, focusing on new risk communication strategies, the collaborative potential of interdisciplinary approaches, and the significance of health physics summer schools and consortia for transformative educational paradigms. The objective of this paper is not only to unravel the multifaceted factors shaping the future of health physics but also to foster dialogue and collaboration for the unpredictable yet exciting journey ahead.