The objective of this note was to systematically study the effects from nonpoint radiation sources on the nuclear medicine imaging room or uptake room shielding design. The dose from a nonpoint source to a location at a certain distance to the center of the source was calculated. A correction factor could be applied to the dose calculated using a point source model with the same distance to compensate the nonpoint source effects. The correction factor was a function only depending on the source relative dimension, the ratio of the source's geometric dimension to the distance. Theoretical and numerical calculation were performed to calculate the correction factor on a one-dimensional line source, two-dimensional circular disc source, three-dimensional sphere, and cylinder sources. Our study indicated that for large nuclear medicine imaging rooms, the point source model was a good approximation for shielding design. For a small uptake room, a nonpoint source correction may be considered to calculate the barrier thickness.

When human body is irradiated by neutrons, the adipose content has a significant impact on the neutron dose and induced 24Na activity. To investigate the effect of human adipose content on the conversion coefficients from 24Na activity to neutron dose, five male adult reference computational phantoms with weights ranging from 73.5 kg to 136.5 kg were used. The Monte Carlo N-particle (MCNP) code was used to calculate the neutron absorbed dose and the yield of induced 24Na in the phantoms irradiated by 252Cf neutrons and monoenergetic neutrons. The results showed that the difference in the conversion coefficients from 24Na activity to neutron absorbed dose among the five phantoms irradiated by 252Cf neutrons with anterior posterior (AP) geometry was ≤23.30%, and this difference was attributed mainly to the neutron absorbed dose, which increases with increasing adipose content. Considering the self-absorption of gamma rays in the human body, the counts of 24Na characteristic gamma rays measured directly by the radiation detector outside of the body have no significant trend varying with adipose content, and the difference in the conversion coefficients from the measured counts to neutron dose among the five phantoms irradiated by 252Cf neutrons with AP geometry was ≤5.25%.

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.

The objective of this note was to study the measurement uncertainties at each step of Yttrium-90 radioembolization. We studied the measurement uncertainty contribution from the dose calibrator accuracy during the initial dose assay, the survey meter accuracy, and the operator's reading uncertainties during the dose rate measurements. The propagation of these uncertainties was calculated to determine the final dose delivery uncertainty for various prescribed doses. The percentage of final dose delivered could be affected significantly by the uncertainties associated with operation at each step of dose assay and dose rate measurements, especially for low prescribed doses.

The author provides a literature review examining the clinical risks of cosmic radiation exposure and incidence of cancer in aircrews including pilots, flight attendants, and flight engineers or navigators. The review focuses on ionizing radiation exposure in aircrews as an occupational working group. The author will discuss the types of cancer associated with cosmic ionizing radiation exposure and the prevalence of certain cancer types noted in this population. Monitoring of ionizing radiation of aircrews in the United States is not required in 2024, which makes assessing exposure a challenge. The author also discusses associated risk factors and prevention strategies in aircrews. United States aircrews are an occupational group with known elevated exposure to ionizing radiation from natural cosmic sources, which has been linked to health risks, particularly for cancer. This occupational group is not monitored in 2024 and would benefit from occupational exams for medical surveillance and hazard awareness.

Lead exposure poses severe health risks to individuals, impacting cognitive function, growth, learning, and behavior. Current lead detection methods, primarily blood testing and x-ray fluorescence (XRF) of bone, have limitations. This study introduces a novel in vivo XRF measurement system using K-shell energies of lead, addressing limitations of previous methods. The study aimed to characterize beam directionality, subject radiation dose, and operator occupational exposure. Using a high-energy x-ray tube and room-temperature detectors, various parameters were assessed with bone and tissue phantoms. Dose measurements were taken by altering voltage, current, and shielding. Scatter and spatial measurements highlighted increased scatter with bone and tissue presence, emphasizing the safest positions for bystanders and operators. Results exhibited expected dose rate changes with varying parameters, showcasing the impact of bone and tissue on scatter radiation. The system's total body effective dose (with an 8-mm molybdenum shielding indicating minimal risk compared to established public dose limits) for an adult was 1.94 μSv; for a child aged 10 y, it was 3.28 μSv. This system demonstrates promising capabilities for lead exposure monitoring, offering negligible occupational exposure and minimal risk to individuals being scanned. Its safety and efficacy position it as a valuable tool in assessing lead exposure, potentially improving preventive measures.

This Note briefly reviews, at a level that is intended to be accessible to non-specialists, the similarities and differences between waveforms of 4G Long-Term Evolution (4G LTE) and 5G New Radio (5G NR) transmitted by cellular base stations, as a resource for health physicists and others who are engaged in public communication about cellular telephone technologies. Despite the difference in levels of controversy presently existing between 4G LTE (introduced in 2008) and 5G NR (introduced in 2019), the differences in waveform as represented by the baseband waveform are minimal, although 5G NR offers system designers a much wider choice of parameters. Transmitted radiofrequency signals in both technologies appear noise-like, in a frequency range that is narrowly contained in the assigned channel. It is concluded that the modulation differences between 4G LTE and 5G NR are unlikely to have any biological relevance, but the greater range of accessible frequencies in 5G NR suggests the need for further health research, particularly in the 5G FR2 millimeter-wave band.

The five populations of rhinoceros species have declined in the wild due to poaching and habitat degradation, with demand for rhinoceros horn driving the poaching industry. The poaching of rhinoceros horn has critically threatened the conservation status of over half of these animals in the world today. To combat this threat and safeguard the species, a method involving the insertion of a radiation source into the rhinoceros's horn has been proposed. This approach aims to deter poachers due to public fear of radiation and enable the detection of smuggled horns based on the source's radioactive properties. To determine the health risks to the rhinoceros, this study presents the dose rate response functions to the rhino's epithelial basal stem cells that form the horn. The assessed responses assumed a modeled source centered at 10 and 20 cm above the basal stem cells. To identify the most appropriate source, dose rates were produced from gamma sources ranging from 0.1 to 2 MeV. Using numerical calculations, conservative dose rate estimates were determined as a function of energy and normalized to source activity, providing a foundation for computational results using Monte Carlo N-Particle Code version 6.2. With the dose rate responses as a function of energy and activity, the risk of deterministic and stochastic effects in this most at-risk tissue were understood based on the skin dose limitations for preventing deterministic effects to the rhinoceros.

During the decommissioning of nuclear power plants, radioactive contaminants may be released into the work environment in the form of aerosols, which can expose workers through inhalation, ingestion, and submersion pathways. During dismantlement work, aerosol concentrations may increase due to release from materials. Typical engineering controls to reduce concentrations include air exchange as well as air filtration, which captures aerosols at their source. This work presents a model of radioactive aerosol concentration to estimate the reduction of (a) effluent aerosol concentration into the environment and (b) worker committed effective dose. Controlling the aerosol concentration mitigates the dose that the workers receive. Given that there exists a variety of filtration methods of varying efficiencies and throughputs, a method of estimating dose reduction for a variety of work scenarios is desirable. This work models the time-evolution of radionuclide aerosol concentration as a function of dismantlement work parameters such as work time, aerosol source rate, air exchange, and air filtration. The committed effective dose to a worker as well as the environmental radionuclide aerosol emissions are estimated over a typical 10-h work shift.

Those responsible for radiological protection in the workplace come to the role through many different pathways. In the process of training radiation safety officers and x-ray safety officers, instructors at the Radiation Safety Institute of Canada have observed that, while many course participants will have previous radiological protection training, it is common for a significant number to have experience managing traditional occupational health and safety or industrial hygiene programs and no radiological protection background. Humans use mental models or schemas to understand the world. They assimilate new information based on their existing schemas. Those formally trained in radiological protection are well versed in the International System of Radiological Protection, based on the fundamental principles of justification, optimization, and limitation as described in International Commission on Radiological Protection Publication 103. Those with training in occupational health and safety or industrial hygiene in Canada or the United States work within a framework called the hierarchy of controls. Given here is a comparison of these safety frameworks with consideration of how the health and safety schema of these two groups of radiological protection personnel may differ and areas on which to build a common understanding of radiological protection in the workplace. Hopefully, consideration of this topic will lead to improved communication and help safety professionals avoid misconceptions that might arise owing to differences in foundational knowledge.

There has long been a need for an objective assessment of the performance of quantitative methods used for continuous particulate air monitors. These methods attempt to estimate the input to the monitor, the airborne radioactivity concentration (or its time integral), from its output, the detector response. This evaluation should include consideration of both the "tracking ability" of each method (i.e., its ability to follow a physically realistic time-varying concentration), as well as its ability to reduce the inherent random variability of its estimates. These two factors are in conflict, in the sense that optimizing one will worsen the other. A prototype scheme for this performance evaluation is presented, which uses a simulation of a fixed-filter monitor response to a known concentration profile and then finds an evaluation score using the residuals between that profile and the method's estimates as generated from the monitor response.

Federal regulations mandate that all radiological workers in the United States, as well as those individuals who may receive non-trivial occupational doses of radiation, must have their external radiation doses monitored and tracked as accurately as possible. Typically, this is done through the use of personnel dosimetry devices, such as optically stimulated luminescence (OSL) dosimeters, which are worn on the body and keep an accurate record of the radiation to which a person has been exposed over a period of time. Unfortunately, the inadvertent passage of OSL dosimeters through airport x-ray security scanners can compromise the accuracy of this running dose record and therefore impede the ability for employers to accurately report work-related doses. With the advent of advanced resolution security technology used in many airports, this once relatively minor issue now requires that the Idaho National Laboratory (INL) Radiological Controls organization be able to accurately discern non-occupational doses received in this way. This research will discuss the methods and models for adjusting dose readings for Landauer InLight Model 2 OSL personnel dosimeters used at the INL that have been subjected to three types of x-ray scans commonly used at airport checkpoints, and the implications of these data across the rest of the US DOE complex.

Ionization chambers with non-sealed volumes find widespread use in monitoring x and gamma radiation. However, the accuracy of results can be compromised by the presence of 222Rn in the air. To investigate this influence, two ionization chambers, each with a 600 cm3 volume and walls constructed of air-equivalent plastic, were exposed to controlled 222Rn concentrations. Following exposure, chamber readings (expressed in units of exposure rate and air-kerma rate) were monitored for 11 d. Two components of the signal attributed to 222Rn and its progeny were identified. The first component, which dominates within the first day after exposure, arises from radon diffusion within the volume through gaps in wall joints. The second component results from radon absorption in the plastic construction materials of the chamber, persisting detectably for over 10 d post-exposure. The background induced by airborne 222Rn can be significant. Concentrations near the reference level in many European countries (300 Bq m-3) can generate signal equivalent to air kerma rate of about 1.34 μGy h-1. This could potentially lead to erroneous radiation protection decisions in radiological departments. Addressing this background can be challenging, as contributions from 222Rn concentrations in previous hours and days impact correction. It is advisable to store such chambers in locations with low 222Rn concentrations and to use construction materials for ionization chambers with low radon absorption ability.

High concentrations of radon may cause radiation damage to the human body. Finding the biomarkers of radon-induced radiation damage is particularly important for the research and treatment of radon-induced lung cancer. In this study, the expression of γH2AX protein in peripheral blood lymphocytes of miners exposed to high concentrations of radon was detected by flow cytometry. To investigate the possible damage in peripheral blood lymphocytes of miners under a high radon environment, a microRNA (miRNA) microarray technique was used to screen the differentially expressed miRNAs in the peripheral plasma of miners exposed to different concentrations of radon. Prediction of the target genes and the possible biological functions of differentially expressed miRNAs in the peripheral plasma of miners was performed. The results indicated that the relative expression level of γH2AX protein in peripheral blood lymphocytes of miners was significantly higher than that of the control group (P < 0.05). Bioinformatics methods were used to predict the differential expression miRNA chip to screen the target genes of differentially expressed miRNAs and the signaling pathways that may be involved in screening differentially expressed miRNA target genes and to investigate the relationship between some different miRNA target genes and cellular pathways. The analysis of the cellular pathways predicted by differentially expressed miRNAs, including the process of cell cycle, provides new information for the study of miRNAs as potential biomarkers of radon-induced radiation damage in peripheral blood.

This paper presents six case studies highlighting real-world incidents in nuclear medicine, focusing on issues such as radioactive contamination, equipment malfunctions, and safety risks. These cases illustrate the challenges faced in maintaining patient and staff safety during complex procedures, underscoring the importance of rapid response and clear communication among healthcare teams. Each case reveals the need for effective contamination control strategies, robust safety protocols, and staff preparedness to handle unexpected situations. The responses to these incidents emphasize the value of continuous staff training and adherence to best practices to minimize risks. This paper also discusses the importance of process improvements and protocol refinements, particularly in managing contamination, ensuring compliance with regulatory standards, and maintaining clinical operations. Lessons learned from these cases offer practical guidance for enhancing contamination control measures, optimizing safety practices, and reducing disruptions to treatment workflows. Finally, this paper emphasizes the importance of preparedness, adaptability, and continuous learning in maintaining a high standard of safety in nuclear medicine.

Water is the basic element for the continuation of human life for all inhabitants, animals and plants on Earth, and water cannot be dispensed with as it is a basis of life. This study focuses on measuring radiation to assess activity levels of some radionuclides in the waters of the Euphrates River, which is the main tributary of drinking water in Najaf, Iraq, and determining whether it is safe for health in terms of radiation. The concentrations of three gamma-emitting nuclides (226Ra, 232Th, and 40K) were measured in a section of the Euphrates River using gamma-ray spectroscopy using a 3" × 3" sodium iodide scintillation detector doped with thallium and connected to software version MAESTRO-32. Twenty-nine water samples were collected at regular intervals along the Euphrates River within the administrative boundaries of Al-Najaf Al-Ashraf Governorate. The Al-Mishkab branch results showed activity concentration levels of 226Ra, 232Th, and 40K that are 3.182 ± 1.514, 1.572 ± 0.509, and 26.715 ± 17.082 Bq L-1, respectively. For Al-Qadesia branch, the activity concentrations are equal to 3.190 ± 1.350, 2.190 ± 1.082, and 37.135 ± 29.464 Bq L-1, respectively, which is within the maximum acceptable concentration levels recommended by the World Health Organization. The annual effective ingestion dose (EID) due to the specific activities of the three nuclides is equal to 0.311 ± 0.103 and 0.357 ± 0.144 mSv y-1 for the Al-Mishkab branch and the Al-Qadesia branch, respectively. The excess lifetime cancer risk (ELCR) values are 1.197 ± 0.395 and 1.373 ± 0.553 × 10-3 for the Al-Mishkab and Al-Qadesia branches, respectively. Therefore, the study concluded that radiation levels in the river water are a significant risk to public health because the concentrations of the studied nuclides are higher than what is globally permitted according to the U.S. Environmental Protection Agency.

Determination of 210Pb, 210Po, 234U, and 238U activity concentrations in groundwater sources used for drinking water can improve confidence in ingestion dose assessments used for comparison with radiological governance guidelines, such as the Australian Drinking Water Guidelines. Such results can provide additional guidance information for detailed assessments where water supplies exhibit high relative concentrations of natural radioactivity. Measurements of these radionuclides, as well as the more commonly measured gross alpha and beta, 226Ra, and 228Ra activity concentrations, were undertaken for 21 water supplies in regional Queensland, Australia. Groundwater was the primary or only source for these water supplies. Dose assessment using the measured values based on the Australian Drinking Water Guidelines assumed water consumption, and estimates of actual consumption rates in the Australian population were undertaken for different age groups. The validity of assumptions underpinning screening assessments based on gross alpha and gross beta activity results and measurement of 226Ra and 228Ra were shown to be valid. The adolescent age group (14-18 y) was identified as a potential critical group for dose assessment where activity concentrations of 226Ra and 228Ra were elevated. Other radionuclides, 210Pb, 210Po, 234U, and 238U were shown to be significant contributors to overall committed effective dose in several water supplies; however, total doses in those supplies were well below the operational dose value of 0.3 mSv from the Australian Drinking Water Guidelines. Improved detection limits for 228Ra could improve accuracy of dose assessments from drinking water.

Introduction: Medical workers account for about 75% of all workers exposed to ionizing radiation; therefore, occupational radiation protection is still a challenge in clinical practices and, consequently, measures should be put in place to optimize radiation in clinical practice. Objective: The aim of this study was to assess the occupational radiation dose for staff in some selected radiology departments in Ghana as a precursor for optimization studies. Methods: A total of 68 occupationally exposed workers (OEWs) radiation dose history for 5 facilities have been analyzed. This study is a retrospective study that involves the assessment of the dose records of occupational exposed workers in five radiology departments in the Greater Accra region of Ghana from the Radiation Protection Institute of the Ghana Atomic Energy Commission (GAEC) dose records history. The OEWs included in the study were radiographers/technologists, radiologist, physicians, medical physicists, and nurses. These records were collected and assessed for a period of 5 years (2019-2023). TLDs are worn under the lead aprons to estimate Hp (10) or deep dose and on aprons for Hp (0.07) or skin dose. Results: A total of 68 OEWs' dose histories for 5 facilities have been analyzed. It was observed that the average annual effective dose for all workers throughout the study period ranged from 0.29 ± 0.07 mSv to 0.41 ± 0.05 mSv. The variations in the mean annual dose for the OEWs for the facilities in the study could be due to the number of OEWs that were monitored and the type and quantity of equipment at the facility during the year under review. Conclusion: The occupational radiation dose for OEWs in some selected radiological departments in Ghana have been evaluated. The facility with the highest number of OEWs recorded relatively higher mean annual effective dose. The annual effective doses were lesser than the yearly occupational dose limit of 20 mSv as recommended by national and international guidelines.

Establishing a relationship between disease and dose requires each individual in the population under investigation to be known by disease status and by the value of the dose received. Frequently, the dose values are reconstructed using a dose assessment model containing imprecisely known parameter values, model formulations, and input data (epistemic uncertainties). As a consequence, the state of knowledge of the assessed dose values needs to be expressed by a joint subjective probability distribution thereby accounting for state of knowledge dependence due to uncertainties shared by the assessed dose values of several individuals. Dose-response analysis must apply this joint state of knowledge in obtaining a subjective probability distribution for the parameters of the dose-response model. This is achieved by drawing a random sample of dose vectors according to the joint distribution, by applying Bayes' theorem for each vector, and by averaging the posterior parameter distributions (Bayesian model averaging). If the dose response is quantified by a binary variable, a logistic regression model is embedded in the likelihood function. This paper presents a new, computationally efficient Bayesian model averaging method that operates over the discretized parameter space and thereby does away with the computational complexities of Bayesian methods. It corrects for the attenuation effect that is due to the application of dose vectors other than the true vector. Results obtained for a sample of dose vectors are compared to those obtained with the standard discrete Bayesian method using the true dose vector.