Health physics最新文献

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.

For the calculation of fractional deposition of radioactive aerosols, the deposition model in ICRP Publication 130 has been widely used. However, the deposition model is based on the anatomical and physiological characteristics of Caucasians. Since physiology and anatomical parameters of Chinese differ from those of Caucasians, this difference can affect the applicability of depositional models to Chinese people. ICRP suggests that the corresponding parameters can be replaced when the parameters of concerned people are known. Therefore, this paper investigates the physiological and anatomical parameters of Chinese people and establishes a respiratory deposition model applicable to Chinese people. It is found that the dependence of fractional deposition on aerosol particle size on Chinese people is qualitatively similar to that in Caucasian people. However, the value of fractional deposition is quantitatively different. When the AMAD (activity median aerodynamic diameter) is 1 μm (public exposure), the ratio of fractional deposition between Chinese and Caucasian light workers could reach up to 1.22 in the AI region, and the ratios of fractional deposition in other regions also ranged from 0.87-0.93; when the AMAD is 5 μm (occupational exposure), the ratio of fractional deposition between Chinese and Caucasian light workers could reach up to 1.35 in the AI region, and the ratios of fractional deposition in other regions also ranged from 0.95-1.30. The fractional deposition is used as input to biokinetic models to simulate the transport of radionuclides through the body after inhalation and ultimately impacts the dose conversion factor calculations.

With the return of residents after the Fukushima Daiichi Nuclear Power Station accident, the measurement results of radiation doses to residents can be used to assess the risk or safety of remaining in their homes. However, personal radiation doses vary depending on the behavior and residential environment of each subject, even for a group of subjects living in the same region at the same time. In past studies, subjects were required to wear a personal dosimeter on their chests outdoors, but they were not required to wear the device indoors. This study investigated the difference between the dose values indicated for the wearing and non-wearing geometries of personal dosimeters during sleep. In particular, an adult human phantom was used to compare the indicated dose values when personal dosimeters were placed on the chest (reproducing the wearing geometry) and near the head (reproducing the non-wearing geometry) in two houses with a high measured radiation dose. Furthermore, to understand the reason for the difference in the indicated dose values, the radiation dose rate during sleep was calculated using a radiation transport calculation code. The dose values for the wearing geometry were approximately 4% lower on the first floor and approximately 15% lower on the second floor than those for the non-wearing geometry. In addition, the radiation dose rates and radiation dose rate ratios (head/chest) differed by approximately 30% and 20%, respectively, depending on the distance from the nearest window (1 to 3 m).

Methods for estimating radiological consequences in terms of radiation doses and cancer risks are needed for informed decisions on mitigation efforts after a radionuclide event. The 1986 Chernobyl Nuclear Power Plant accident fallout in Sweden was used as a case study. Open-source data on annual sex-specific population data in 1-y classes by municipality (n = 290), counties (n = 21), and future projection were retrieved from Statistics Sweden from 1986 to 2035. Published organ dose coefficients, cancer risk coefficients, and established methods for dose calculations and cancer risk projections were applied to estimate organ absorbed doses (mGy), effective dose (mSv), collective dose (person-Sv), and lifetime attributable risk (LAR). Due to the geographically variable Chernobyl fallout in Sweden, the variability in absorbed organ doses was greater between municipalities and counties than between organs or sexes. LAR was translated into 377 male and 448 female extra cancer cases over 50 y post-Chernobyl. Overall, 38% of these cancer cases could be attributed to the internal dose in males and 32% in females. The highest number of cancer cases was estimated for Västernorrland county, with only 3% of the Swedish population in 1986, but 18% of the excess cancer cases 1986 to 2035. The collective dose was calculated to 6,028 person-Sv, whereas 2,148 person-Sv (36%) was internal dose. Like for LAR, the population of Västernorrland county got 18% of the total collective dose. The excess number of cancer cases derived from LAR and collective dose gave similar results. Our methods can be adopted to other countries and different fallout scenarios.

Cobalt is an essential element with a wide range of applications. It is made up of one stable isotope ( 59 Co) and 36 radioactive isotopes, including 60 Co, the only one with a half-life of more than one year. It is an activation product, and irradiation is the main mode of exposure to 60 Co. Nevertheless, the risk of internal contamination should not be overlooked, particularly for workers who may be involved in maintenance tasks in nuclear power plants or on dismantling sites. The general population may also be affected in the event of a reactor accident where 60 Co would be released with other radionuclides. The health effects of exposure to stable cobalt are mainly respiratory and cutaneous. However, the recently revealed carcinogenic nature of certain cobalt compounds calls for vigilance. Otherwise, the radiotoxicity of cobalt has not yet been explored. In view of the many uses of cobalt and the potential exposures identified, effective means of protection for humans and their environment are of paramount importance. To date, in the event of incorporation by inhalation, ingestion, or cutaneous injury, the current pharmacological treatments offer perfectible efficacy. This review article outlines an updated state of knowledge on cobalt, with a special focus on its biokinetic and toxicological data, the recommended medical countermeasures, and the research in progress in this field. Finally, this review suggests new research perspectives, particularly in the field of medical countermeasures, an area of utmost importance in terms of radiation protection and occupational health.