Health physics最新文献

Abstract: Radiation protection contains the key elements of nuclear safety and security. Despite the overlap between nuclear safety and security, their objectives differ fundamentally, focusing on unintentional accidents and intentional malicious events, respectively. As such, the Potential Facility Risk Index (PFRI), originally created for security purposes, has evolved into an approach that combines conventional probabilistic risk assessment (PRA), which is a widely employed method to evaluate the safety risks of nuclear facilities. This research has developed a risk assessment model within the PFRI framework to calculate the probability of nuclear terrorism. Three essential components of the model are integrated: an analysis of historical nuclear terrorism data to determine an initial threat frequency; the target-specific factor using analytical hierarchy process (AHP) target attractiveness analysis; and the adversary motivation factor based on site-specific social influences from the Profiles of Individual Radicalization in the United States (PIRUS) dataset. Applied to a hypothetical nuclear facility, the model produces a nuclear terrorism probability of 8.97 × 10-3 y - 1. The systematic methodology proposed in the study enables the derivation of nuclear terrorism probability with results in the same risk unit as safety risk assessment. This method allows decision makers to seamlessly incorporate nuclear safety and security risk assessments, offering a comprehensive perspective. Consequently, it enriches comprehension of nuclear facility risks and establishes the groundwork for future advancements.

Abstract: Personal radiation protective equipment (PRPE) is prone to defects in the attenuating layers, resulting in inadequate protection. Hence, quality control (QC) of PRPE is needed to assess its integrity. Unfortunately, QC of PRPE is laborious and time consuming. This study aimed to predict the QC outcome of PRPE without x-ray imaging based on readily available predictors. PRPE QC data of a general hospital from 2018 to 2023 was used for both prediction models based on logistic regression and random forests (RF). The data were divided into a training set containing all data from 2018 to 2022 and a holdout set containing the data from 2023. The predictors were brand, age, size, type, visual defects, and department. The prediction performances were compared using confusion matrices and visualized with receiver operating characteristic (ROC) curves. Prediction accuracies of at least 80% were achieved. Further model tuning especially improved the RF model to a precision up to 97% with a sensitivity of 80% and specificity of 86%. All predictors, except visual defects, significantly impacted the probability of passing. The predictor brand had the largest contribution to the predictive performance. The difference in pass probability between the best-performing and the worst-performing brand was 35.1%. The results highlight the potential of predicting PRPE QC outcome without x rays. The proposed prediction approach is a significant contribution to an effective QC strategy by reducing time consuming x-ray QC tests and focusing on garments with higher probability of being defective. Further research is recommended.

Abstract: Standard lead aprons do not protect the female breast adequately from radiation exposure, which has been associated with breast cancer in healthcare workers. A novel lead shield was designed to reduce radiation to the breast, axilla, and thyroid (BAT). A procedure room was simulated with an anthropomorphic phantom representing the operator. Dosimeters were positioned on the outer quadrant of each breast, the chest, the thyroid, and deep inside of a phantom acrylic female torso with neck and head. Standard lead vest plus a thyroid shield was used as control and compared to standard lead vest plus BAT shield. Three operator and two image receptor positions were tested. The reductions in radiation exposure were calculated. The standard vest plus BAT shield provided significant reductions in radiation exposure for all anatomic locations compared to control. When averaging all operator positions, the BAT provided reductions of 91% (p < 0.0001) for near breast. Reductions for far breast, chest, thyroid, and deep tissues were 76% (p = 0.016), 94% (p < 0.0001), 52% (p = 0.026), and 60% (p = 0.004). With operator 90° to the table using a cross-table lateral beam, the BAT provided a 97.7% reduction in radiation to the near breast and significant reduction in radiation to the chest, thyroid, and deep tissues. The BAT shield reduces radiation exposure to the breast, chest, thyroid and deep hematopoietic tissues. Such shields could benefit healthcare workers to reduce the risk of breast cancer and other radiation-associated cancers.