Health physics最新文献

Abstract: Many medical facilities across the United States use ionizing-radiation-producing machines and radioactive materials for diagnostic and therapeutic purposes on a regular basis. While institutions are required to ensure full-term fetal doses are below the regulatory limit, clear guidance on how pre-declaration fetal doses should be estimated is not available. This paper provides a process that can be used to estimate the pre-declaration fetal dose and provides a predictive screening tool for licensees to use to recommend workload adjustments prior to actual fetal dosimetry results that could exceed the institutions derived investigation levels. The evaluation process presented herein serves as a guide for medical licensees when performing fetal dose evaluations for declared pregnant workers.

Abstract: Alpha DaRT is a new alpha radiation treatment for treating solid tumors and is currently being evaluated through clinical trials worldwide. Being a novel radiation treatment, it is important to discuss the safety considerations and procedures that are needed to ensure safe use of this unique approach. The objective of this article is to provide a set of recommendations-radiation safety best practices that were developed based on operational and clinical experience.

Abstract: This work investigates the low photon radiation dose (≤50 mSv) response of commercially available radiochromic films as a potential field dosimeter that could be used by the Canadian Armed Forces to complement their existing personal radiation dosimeters. The films were exposed to various photon energies from x-ray devices and radioisotopes (cesium-137, cobalt-60, and americium-241), and their radiation signal was read using three methods: net optical density, UV/visible spectroscopy, and Fourier transform infrared spectroscopy. A complimentary film dosimeter for field usage should, for military use, display a visual color change and detect doses ≤50 mSv. Given the film's radiochromic properties, it was determined that the net optical density method was the most optimal read-out method, which ascertained a minimum detection dose limit of 4.5 mSv under exposure to a clinical orthovoltage operated at 100 kVp. The film presented an overall linear relationship between net optical density and radiation dose; however, they also portrayed a photon energy-dependent response between 0-100 mSv. Overall, the radiochromic films presented a real-time visual dose signal that could be interpreted rapidly in a mobile laboratory and possessed the ability to detect photon doses ≤50 mSv below the vendor's recommended limits, making it a suitable option as a complementary, disposable, military dosimetric tool. Future work includes the investigation of the film's response under multi- and unknown source environments and environmental-dependent factors such as UV/sunlight exposure and extreme temperatures.

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: This paper investigates the link between gaps in emergency responders' notions of mental model regarding radiation and risk and their effectiveness in responding to radiological incidents. Particularly, this work focused on exploring themes that emerged in prior work related to improper understanding and application of knowledge concepts related to radiation risks and Radiological Dispersal Device (RDD) scenarios (Leek et al., 2024b). The research uses a quantitative approach to correlate various thematic elements, such as responders' confidence levels, comprehension, and application of radiation risk principles, with the quality of the emergency response score gained through a virtual reality simulation. The results underscore a strong effect of responders' confidence level on response quality scores. Additionally, the study identifies that improper understanding of knowledge concepts and incorrect application of radiation risk and RDD concepts are factors that detract from the quality of response, especially the tendency to overestimate health risks associated with a 25-rem (0,25 Sv) dose and to misapply principles of radiation risk. The implications of this research are significant for the development and refinement of training programs for hazardous materials (HAZMAT) technicians and other emergency responders. The findings suggest the need for a comprehensive review of current training methodologies to address the identified deficiencies that had impacts on the quality of response. The findings provide a foundation for reshaping training priorities and operational readiness, driving the development of training that is both grounded in empirical evidence and that directly addresses the knowledge gaps influencing response quality. The methodological framework developed and employed, including the quality scoring system and the Expected Mental Model State (EMMS) Diagnostic Matrix, also hold potential for broader application in future investigations, extending to diverse types of responders and emergency scenarios.

Abstract: After some consumer products indicated elevated levels of 232Th progeny by gamma-ray spectrometry, a microwave digestion and inductively coupled plasma-mass spectrometry (ICP-MS) procedure was implemented for the direct assay of 232Th content to ensure compliance with Federal regulations and guidelines. Levels of 232Th were determined by ICP-MS based on standard calibration using a 205Tl internal standard. The method had a method detection limit (MDL) of 0.15 Bq g-1 and a lower limit of quantification (LLOQ) of 0.65 Bq g-1 for 232Th, making it a suitable confirmatory method following gamma-ray spectrometry. The 232Th activity concentration calculated from the ICP-MS results ranged from 2.0-3.4 Bq g-1 for the kinesiology tape samples and 20 Bq g-1 for the silicone ion bracelet. The VARSKIN+1.0 software program was used to calculate the shallow dose equivalent of ionizing radiation from 232Th and its progeny from the ICP-MS results. The skin dose to the consumer wearing the kinesiology tape ranged from 0.48-1.6 mSv y-1. The skin dose to the consumer with constant wear of the silicone ion bracelet was estimated to be 17 mSv y-1. Although 232Th may be determined indirectly by assay of high abundance gamma rays produced by its progeny, the US Code of Federal Regulations (CFR) requires the direct assay of 232Th for confirmatory analysis. We found this ICP-MS method to be a rapid 232Th confirmatory technique compared to a chemical separation followed by alpha spectrometry procedure.

Abstract: The Institute of Electrical and Electronics Engineers establishes exposure reference levels (ERLs) for electric fields (E-fields) (0-300 GHz) and both induced (IIND) and contact currents (ISC) (<110 MHz) in its standard, IEEE Std C95.1™-2019 (IEEE C95.1). The "classical" scenarios addressed in IEEE C95.1 include a free-standing, grounded "reference" person (IIND) or an ungrounded reference person in manual contact with an adjacent grounded conductor (ISC), each exposed to a vertically oriented E-field driving the currents. The ERLs for current from 100 kHz to 110 MHz were established to limit heating in the finger (from touch), ankle (IIND), and wrist (ISC from grasp contact), specifying the 6-min average specific absorption rate (SAR, W kg-1) as the dosimetric reference limit (DRL); whole-body E-field ERLs are 30-min averages. The DRLs were established assuming a default "effective" local cross-section (9.5 cm2) and consistent with a composite tissue conductivity of ~0.5 S m-1. A previous publication described the misalignment of the ERLs for E-fields with the ERLs for IIND (which extends to ISC) and also proposed a ramped E-field ERL from 100 kHz to 30 MHz. For the frequency range 100 kHz to 110 MHz, this paper proposes temperature increase (ΔT) in ankle and wrist as the preferred effect metric associated with IIND and ISC; applying the E-field ERLs as surrogates for limits to these currents; and adopting the proposed ramp. The analysis of ΔT is based on the tissue mix in realistic anatomic depictions of ankle and wrist cross-sections; relevant tissue properties posted online; published tissue perfusion data; and anthropometric data on a large sample of male and female adults in the US military, allowing an estimate of effects over a range of body size. To evaluate ΔT versus frequency and time, the Penne bioheat equation was adapted with convective cooling from arterial blood as the lone cooling mechanism. The analysis revealed that IINDs and ISCs induced by ERL-level E-fields produce SARs in excess of the local DRLs (in some cases far exceed). Calculations of time to ΔT of 5 °C, reflective of a potentially adverse (painful) response, resulted in worst-case times for effects in the ankle on the order of minutes but on the order of 10s of s in wrist. Thus, compliance with the E-field ERL, as assessed as a 30-min whole-body average is incompatible with the time course of potentially adverse effects in ankle and wrist from IIND and ISC, respectively. Further analysis of the relevant exposure/dose scenarios and consensus of stakeholders with a multi-disciplinary perspective will enable the development of a revised standard, practical from a compliance perspective and protective of all persons.

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 232Th and 137Cs 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 232Th or a significantly lower activity of 137Cs 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: The aim of this study was to investigate the effects of tube current and tube voltage choices on patient dose in adult and pediatric CT protocols by qualitative analysis using Principal Component Analysis (PCA), cluster analysis, and statistical analysis.Dose length product (DLP), Effective mAs (Eff. mAs), and volume-weighted CT dose index (CTDIvol) dose descriptors were obtained from 16 adult and pediatric head phantom CT examinations. Different tube voltage and tube current values were selected in both pediatric head and adult head CT imaging protocols, and PCA and cluster analysis were applied to the data obtained for qualitative analysis of the relationship between CTDIvol, Eff. mAs and Total DLP values. The two principial components (PC) with the highest values among those obtained as a result of the PCA method were used. PC1 was 70.97%, and PC2 was 28.03%. In the cluster analysis, it was observed that the values obtained from pediatric and adult phantom CT scans were classified into two different clusters. The correlation coefficient for adult patients was r = 0.998, and for pediatric patients, the correlation coefficient was r = 0.947. When the obtained clusters were examined, the degree of closeness or distance of the variables could be observed. In the study, as a result of the analysis of CTDIvol, Eff. mAs and Total DLP data based on manufacturer data at different kV and mA values with PCA and cluster analysis, it was shown that pediatric patients could be exposed to more radiation than the adult patients.

Abstract: Objective: To evaluate the effectiveness of a general education course titled "The Basis of Radiation Protection" in building and strengthening undergraduate awareness of radiation safety and cultivating innovative individuals with reasonable knowledge structures and strong practical abilities. Methods: All students from 2021 to 2022 enrolled in the core general education course "The Basis of Radiation Protection" at Shandong University of China were invited to participate. A questionnaire survey was conducted to determine changes in the students' basic cognition of radiation safety and scientific protection before and after the course. Results: The survey indicated that the cognitive level of radiation science protection had significantly improved through course completion. The Liszt quantification score range increased from 3.45 to 4.77 to 4.81 to 4.98 (p < 0.001). Further analysis revealed that different professional backgrounds significantly affected students' understanding of radiation safety protection; medical students were superior to electrical engineering students in their knowledge of ionizing radiation before the course (p < 0.001). However, after course completion, the understanding of students from both majors regarding radiation safety had relatively improved, and no significant difference was detected (p > 0.05). Feedback on the course showed that the awareness of "daily radiation protection" had significantly improved (96.8%), pseudoscience and pseudo-information could be correctively identified (93.6%), "nuclear power"-related fears had been dispelled (95.7%), and the concept of "cherishing life" had been effectively established (91.5%). Conclusion: The course effectively improved the awareness of radiation safety, strengthened the knowledge system, and provided a new way to cultivate innovative talent with reasonable knowledge structures.