Health physics最新文献

Staff members in radiology departments face radiation exposure as a primary work-related risk according to safety guidelines. This research evaluates knowledge, attitudes, and practices (KAP) regarding radiological protection protocols of radiology workers in Jordan. The research employed a cross-sectional analysis using a questionnaire administered to 203 professionals from the groups of radiologists, medical physicists, radiologic technologists, and nurses. Among the participants, 44.3% held a bachelor's degree, 41.4% had a diploma (two-year technologist certification), and 14.4% held higher qualifications. The average knowledge score was 46%, with notable deficiencies in key areas such as radiation dose limits and tissue sensitivity. Attitudes towards radiation safety were generally positive, with scores ranging from 55.7% to 86.2%. However, inconsistent safety practices were observed, particularly in the use of personal protective equipment (PPE). Despite 87.19% using personal dosimeters, only 58.13% consistently used lead gloves, goggles, and thyroid collars, highlighting the need for further improvements. Staff members displayed inconsistent practices especially regarding their use of personal protective equipment during work shifts. Radiology professionals require specialized training programs which help raise compliance levels and foster safe practices in their work environment.

Accurate neutron dose assessment in humans is critical for radiation protection and nuclear emergency medical rescue. This study aims to establish a reliable method for evaluating neutron doses using a newly developed voxel physical phantom and to determine the lower detection limit of neutron absorbed dose via 24 Na activity measurement. A voxel physical phantom, based on the ICRP 110 male adult reference computational phantom, was constructed using tissue-equivalent materials and sodium carbonate solutions to simulate sodium content in various organs. The phantom was irradiated with 252 Cf neutrons, and the induced 24 Na activity was measured using a 3-inch NaI(Tl) detector. Monte Carlo simulations were employed to validate the neutron fluence and dose distribution within the phantom. The results showed that the whole-body neutron absorbed dose in the voxel physical phantom differed by less than 3.1% compared with the ICRP 110 male adult reference computational phantom, with induced 24 Na activity deviations of less than 3.0% for the whole body and 20.0% for major tissues and organs. When using a 3-inch NaI(Tl) detector to evaluate the neutron absorbed dose of the ICRP 110 male adult reference computational phantom irradiated with 252 Cf neutrons instantaneously by measuring the induced 24 Na activity, the lower limit of neutron absorbed dose detection was ≤ 31 mGy. This demonstrates the accuracy of neutron dose assessment using computational phantoms, providing a practical and cost-effective alternative to conventional approaches.

External exposure due to secondary photons (predominantly bremsstrahlung) generated from electron source emissions in environmental soil are of concern due to their ability to deposit significant amounts of ionizing energy to organs and tissues within the body. The "condensed history method" employed in many modern Monte Carlo (MC) codes may be used to simulate secondary photon yields (given as photons per beta decay) arising from electron source emissions with relatively few assumptions regarding the secondary photon spatial, energy, and angular dependencies. These yields may in turn be used to derive protection quantities such as secondary photon effective dose rate (DR) and risk coefficients for a variety of idealized external exposure scenarios. Use of the condensed history method is, however, computationally burdensome when simulating idealized external exposure scenarios even with available parallel computing resources. Consequently, use of the method was largely prohibitive for prior environmental dosimetry and risk assessment applications that required innumerable MC simulations for deriving secondary photon protection quantities. A MC method has herein been proposed for estimating secondary photon yields from electron source emissions in environmental soil with the condensed history method in a computationally feasible manner using the Monte Carlo N-Particle version 6.2 (MCNP6.2) radiation transport code. The proposed method was demonstrated with radiation transport models of idealized external exposure scenarios patterned after Federal Guidance Report (FGR) 15, and secondary photon yields determined using the proposed method and a previously adopted analytical method were compared.

Inhaled radioactive materials can pose a long-term health concern, as the material can be incorporated into the body's metabolic pathways and remain in organs and tissues for extended durations. During the retention period, the radioactive material may localize in a source organ and irradiate adjacent target organs and tissues. Distribution of these materials changes over time, requiring biokinetic modeling to evaluate their movement through various tissues and organs. The evolving distribution depends on multiple inputs characterizing the inhaled material, such as particle size and size distribution, particle density, aspect ratio, specific radionuclide, the chemical form, and solubility. In addition, biological parameters such as breathing rate, breathing type (nasal or nasal/oral), respiratory system morphometry, tidal volume, functional residual capacity, and anatomical dead space all influence material transport. These aerosol properties and physiological characteristics of the respiratory tract jointly define a range of initial conditions that influence the time-dependent distribution of radioactive material. To evaluate both uncertainty in the initial conditions of inhalation exposure and the final output (committed effective dose) from biokinetic models, a Python-based software tool, Radiological Exposure Dose Calculator (REDCAL), was developed to propagate uncertainty within the human respiratory tract model. Focusing on deposition fraction uncertainty, the primary objective was to characterize the initial activity distribution across respiratory regions as a function of anticipated particle sizes and distributions. The impact of the deposition fraction uncertainty was propagated to committed effective dose coefficients for selected radionuclides in a companion publication. For each particle size, a lognormal distribution, characterized by its geometric mean as defined within ICRP Publication 66, serves as the basis for introducing uncertainty into the physical processes governing deposition in various lung regions. This study addresses the deposition process and examines how uncertainty in deposition mechanisms affects activity distribution in the airways, ultimately presenting the expected range and standard deviation of deposited activity as a function of particle size.

Reference inhalation dose models rely on deterministic biokinetics and reference computational phantoms, limiting their applicability to the variability present in population-specific exposures encountered in emergency response scenarios. This study introduces REDCAL, a Python-based computational framework developed to propagate uncertainty in inhalation dose coefficients using the International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model. REDCAL integrates ICRP deposition and clearance models, systemic biokinetics, and governing physics principles, and leverages Sandia National Laboratories' Dakota toolkit for uncertainty quantification via Latin Hypercube Sampling. REDCAL was validated against DCAL, with biokinetic retention results differing by less than 1% and effective dose coefficients by less than 2% across all tested radionuclides. Stochastic sampling introduced variability in dose coefficients, with geometric standard deviations (GSD) in committed effective dose coefficients (CEDC) ranging from 1.0 to 1.5, based on lognormal distribution fits. Analysis demonstrated that variations in the activity median aerodynamic diameter (AMAD) notably influenced the computed CEDC values. Smaller particles (<1 µm) increased doses by 20-30% due to deeper lung deposition and prolonged retention for alpha emitting radionuclides, such as 241 Am and 239 Pu. Radionuclides with fast clearance, such as 133 I, demonstrated a dose reduction exceeding 50%, as AMAD increased beyond 5 µm due to upper airway deposition and rapid mucociliary clearance. The greatest GSD among the radionuclides reported in this study was for 241 Am. In most cases, the largest GSDs in the CEDC were associated with larger particle sizes, an expected outcome, as ICRP Publication 66 defines GSD in particle size as a function of AMAD, resulting in an extended tail of the lognormal distribution. The findings support improved inhalation dose assessments and enhance consequence management strategies for the U.S. Federal Radiological Monitoring and Assessment Center by quantifying uncertainty in dose coefficients and strengthening decision-making for emergency response scenarios.

With the widespread application of vehicle-to-vehicle (V2V) communication technology, sunroofs have enhanced user experience while introducing novel electromagnetic exposure scenarios that may pose health risks to drivers. This study employs COMSOL Multiphysics to simulate three sunroof scenarios (no sunroof, sunroof closed, and sunroof open) to assess human exposure levels. The computational models incorporate a full-scale vehicle, a V2V antenna, and an anatomical human model. The whole-body averaged specific absorption rate (SARwb) and SAR averaged over 10g tissues (SAR 10g ) in the central nervous system (CNS) are assessed against the International Commission on Non-Ionizing Radiation Protection (ICNIRP) public exposure limits. The results indicate that the sunroof open condition (worst-case exposure scenario) significantly increases SAR deposition, with SARwb reaching 0.318 mW kg -1 (0.396% of the ICNIRP limit of 0.08 W kg -1 ). This value represents a 1.45 times and 4.68 times increase compared to the sunroof closed and no sunroof conditions, respectively. In the worst-case exposure scenario, the superficial skin tissue exhibits the maximum SAR 10g (72.39 mW kg -1 ), representing a 29.30% increase compared to the sunroof closed state (55.99 mW kg -1 ) and corresponding to only 3.62% of the ICNIRP limit (2 W kg -1 ). Simultaneously, CNS tissues exhibit significant increases in SAR 10g values, with grey matter displaying the most pronounced elevation (9.58 times), exceeding that of white matter (9.08 times) and thalamus (8.99 times). All results remain below the ICNIRP limits, confirming that V2V communication systems pose no health risks to drivers and provide a basis for occupant protection in connected vehicles.

For far too long, we scientists and engineers have allowed unsubstantiated fear of low-level radiation (LLR) among the public to prevail. And we have failed! Why? We propose two main reasons for this failure: (1) Our profession is divided - International agencies such as ICRP still claim radiation can be dangerous down to trivial levels whereas the science claims precisely the opposite. As such we can't blame the public when they get mixed messages. (2) Even when the truth about safe low-level radiation is explained to the public, decisions are made via emotions (stimulated by fear), not facts. We propose the path forward be guided by new medically validated psychological findings that likely have significant bearing on the two issues noted above. This new psychological insight notes that our brains are wired in a predictive mode, rather than a reaction mode. Hence, when we encounter new information, we deal with it within a framework that fits with past experience. If such new information is in conflict with this expectation, it is highly suspect and likely discarded as biased input. We see this reflected even in our highly respected international organizations such ICRP. The scientists occupying major roles in such institutions are certainly well-meaning, world-class scientists. But is it possible that they enter these roles with a background experience suggesting radiation may always be harmful - and they look for ways to confirm their past beliefs? Even if they find new scientific evidence that LLR is not harmful (and possibly even beneficial) they want to err on the conservative side. But is such a stance really conservative - when we note that there was not a single death at Fukushima due to radiation? Rather, it was the fear of radiation caused by the prevailing assumption that there is no threshold for radiation damage. So, Challenge #1 in our efforts to eliminate fear of LLR is the step to achieve a unified international message, based on science, not to fear LLR. Challenge #2 is to then convey this message to skeptics, recognizing that is emotion, not facts, that will ultimately change minds.

During the initial screening of their water supplies for radioactivity, members of the public often have questions about high gross alpha/beta results, but there is not a specific radionuclide of concern identified. In an ongoing groundwater testing project in Whitehorse, Yukon, uranium concentrations that correspond to guidance levels (e.g., 20-30 μg L-1) were found to cause exceedances of the gross alpha screening criteria (e.g., 0.5 Bq L-1). Ninety-five percent of these samples were also observed to have a 234U/238Uactivity ratio >1, which puts caution in trying to apply a universal correction factor for the gross alpha activity. These results will help inform the next revision of Canada's drinking water guidelines for radiological parameters and the type of water testing considerations that could be communicated to the Canadian public.

After implementing a process for flagging readmitted radiopharmaceutical therapy patients, it was discovered that major assumptions for these patients were not correct, specifically the magnitude of patients and the location of the readmissions. Data collected from May to December 2024 revealed 501 post-therapy patient encounters out of 1,139 administrations. Analysis showed varying return rates across different radiopharmaceuticals and departments, highlighting the need for updated radiation safety response. Results indicated that most encounters occurred in outpatient settings, with contamination above action levels found in 61% of responses. The study underscores the importance of continuous assessment and collaboration among stakeholders to adapt to new radiopharmaceutical therapies and ensure effective radiation safety practices.

The radiopharmaceutical therapy field is experiencing a surge of novel treatments and expanded uses for existing treatments, broadening the range of patients that can be treated. This expansion presents new challenges for managing patient release due to new patient populations with additional comorbidities, increasing the incidence of patients requiring care shortly after administration. This paper outlines the challenges and potential solutions for managing readmitted radiopharmaceutical therapy patients. It discusses the importance of having radiation protection policies and procedures in place for staff who may be unfamiliar with radiation. The paper also highlights the need for just-in-time training and radiation monitoring equipment for care staff, as well as the development of a notification system within the electronic health record to ensure staff can safely care for these patients. Preparing for these eventualities is essential for implementing a radiopharmaceutical therapy program that is ready for the expansion of existing and novel treatments.