Radiation protection dosimetry最新文献

Recent years have witnessed an increase in mortality and morbidity from chronic diseases unrelated to tumors in patients with malignant tumors. While radiation therapy reduces local tumor recurrence, it may elevate late mortality from cardiovascular diseases (CVD). The relationship between radiotherapy for cancer and CVD risk remains debated. This study analyzed the surveillance, epidemiology, and end results (SEER) Database from 1975 to 2014, focusing on long-term CVD observation periods of 1, 5, and 10 y. We tracked patients from cancer diagnosis to death or last follow-up, calculating hazard ratios (HRs) and 95% confidence intervals (CIs) for cardiovascular-specific survival (CVSS) using Fine-Gray binary competing risk regression analysis. Our analysis included 303 665 patients diagnosed with rectal (18 398), breast (276 263), and cervical (8004) cancers. Among these, 7098 (2.34%) died from CVDs. Rectal cancer patients undergoing radiotherapy, mainly in later stages, showed a reduced risk of CVD mortality (HR = 0.72, 95% CI: 0.61-0.84). Breast cancer patients treated with radiotherapy, who generally had smaller tumors, experienced significantly lower cardiovascular mortality (HR = 0.48, 95% CI: 0.46-0.51). Conversely, cervical cancer patients receiving radiotherapy had a higher rate of CVD mortality (HR = 2.14, 95% CI: 1.30-3.52). The AUC values for 3-y CVSS were 0.788, 0.837, and 0.821 for rectal, breast, and cervical cancers, respectively, indicating good predictive accuracy. The impact of tumor radiotherapy on CVD outcomes appears cancer-type specific, with cervical cancer radiotherapy increasing the risk of cardiovascular morbidity and mortality.

Internal contamination with plutonium (Pu) isotopes represents one critical exposure scenario in nuclear fuel cycle facilities. Lung counting is commonly employed as the initial individual monitoring method following inhalation of Pu. Due to the low detection sensitivity for characteristic X-rays emitted by Pu isotopes, the γ-ray emitted by coexisting 241Am is typically used as a surrogate for measurement. However, it is essential to establish clear procedures applicable in cases of severe internal exposure. In this study, key challenges associated with lung counting and dose assessment were examined, focusing on an inhalation event of reactor-grade Pu compounds containing 238Pu to 242Pu. These challenges included: complex spectral peak analysis; increased minimum detectable activity for Pu isotopes due to interference from 241Am; and evaluation of the minimum assessable dose considering Pu isotopic composition. Based on these considerations, procedures from lung counting to internal dose assessment were refined to support emergency response.

This study investigates computed tomography (CT) dose management and automatic dose monitoring software (DMS) use in Australian radiology departments. An online survey covering departmental characteristics, dose management practices, DMS usage, and radiation protection activities was distributed through national radiation organisations and social media. Of the 132 initial responses received, 45 were eligible, completed, and analysed. The findings indicate 91% (n = 41/45) of departments regularly assess CT doses, with 63% (n = 26/41) conducting such assessments only once a year. Automatic DMS tools were utilised by 41% (n = 17/41) of these departments for CT dose data collection and analysis, while 59% (n = 24/41) relied on traditional methods. Only 25% (n = 6/24) of non-DMS users indicated plans for future adoption. A radiation protection team was present in 41% (n = 17/41) of departments. While dose assessment is commonly practised, it mostly relies on manual methods and is performed infrequently. Broader DMS implementation and formal radiation protection teams are recommended to strengthen CT dose management and enable continuous monitoring.

The dicentric chromosome assay serves as the "gold standard" for biodosimetry, playing a crucial role in rapid clinical decision-making during extensive nuclear radiation incidents. This study aimed to develop a semi-automated dose-response curve for the analysis of dicentric chromosomes induced by irradiation of human peripheral blood lymphocytes with 60Co gamma rays. Blood samples were collected from three healthy donors and subjected to irradiation, culture, and harvesting, following International Atomic Energy Agency standard protocols. The Metafer4 system, an automatic scoring system, was utilized to acquire images of the metaphase chromosome segregation phase, and the dose-response curve was constructed through automatic analysis of dicentric chromosomes supplemented by manual verification. The curve was subsequently validated through blind scoring. The results demonstrated that the semi-automated scoring method provides quick and precise dose estimations and offers a viable alternative to manual dicentric chromosome assay. This approach holds significant potential for application in the nuclear emergency management of large-scale radiological events.

The High-Intensity Proton Accelerator Facility at the Paul Scherrer Institute (PSI) accelerates protons to an energy of 590 MeV with currents up to 2.4 mA, i.e. 1.4 MW beam power. The beam feeds four main experiments using individual targets. The areas adjacent to these targets are heavily shielded by several meters of iron and concrete. The neutron stray field at different positions outside the shielding close to two of these targets has been investigated using the PSI extended range Bonner sphere spectrometer (ERBSS). It consists of 10 moderator spheres made of polyethylene and 4 spheres modified with metal shells, enhancing the sensitivity for neutrons with energies >20 MeV. The data was normalized to the proton current measured by a resonance chamber upstream of the first target. Two commercially available survey instruments for neutron radiation constantly monitored the stability of the field during the measurements. The spectral neutron distribution was determined by applying Bayesian methods, which were optimized for measurements of neutron stray fields behind shielding at high-energy accelerators. The measurements within restricted access areas resulted in ambient dose equivalent rates of 25-50 μSv (h mA)-1 with significant contributions of high-energy neutrons. The comparison to doses indicated by a commercially available survey instrument suitable for measurements in fields with a high-energy neutron component showed reasonable agreement with the dose values obtained from the ERBSS measurement. However, it is desirable to apply in-field calibration factors derived from spectrum measurements to reduce the uncertainty of dose values obtained with survey instruments.

This article aims to assist authors in presenting good topics correctly when publishing in the field of radioecology in the Radiation Protection Dosimetry (RPD). It is also intended to help reviewers in reviewing and improving submitted drafts. The topics covered in this article are based on the experience the authors have gained in recent years as reviewers and co-editors of the RPD. The guidelines in this article aim to improve the quality of submissions and ensure that lower-quality submissions are either significantly improved or withheld. We only address a few typical points here and point out that these editorial comments refer exclusively to the above-mentioned field of radioecology.

Introduction: Surgical C-arms are essential tools in pediatric surgery in various specialties. The selection of an appropriate C-arm for pediatric use is critical, as manufacturers offer different balances between radiation dose and image quality.

Objective: This study introduces a practical measurement protocol that enables straightforward comparison of C-arms using readily available tools in most facilities.

Methods: A measurement protocol for evaluating radiation dose and image quality across different C-arm models for pediatric use is suggested. To illustrate this methodology, seven C-arm models from three manufacturers were assessed using a polymethyl methacrylate phantom to simulate pediatric patients. Dose and image quality were measured across various configurations, including fluoroscopy and low-dose modes, while considering features like additional copper filtration, anti-scatter grid removal, and field zoom.

Results: Dose and image quality measurements on C-arms illustrate the methodology's application and the impact of fluoroscopy parameters and pediatric-specific features on dose and image quality. Recommendations are provided to guide the selection and optimization of C-arms for pediatric surgery, ensuring the best compromise between dose reduction and diagnostic image quality.

Conclusion: This study introduces a practical method for evaluating C-arms in pediatric settings, helping to improve equipment selection and optimize imaging protocols for safer pediatric imaging practices.

In radiological imaging, much research has been conducted on tube voltage and additional filters to reduce radiation exposure. In this study, the usefulness of heavy metal filters in lumbar spine imaging to maintain image quality and reduce radiation dose was investigated. A human-body phantom was irradiated with various combinations of tube voltages (70, 75, 80, 85, and 90 kV) and filters (Cu, Gd, Ho, Yb, W). For all beam qualities, the mAs value was adjusted so that the amount of CsI fluorescence at each dose after passing through the phantom was the same, and the contrast-to-noise ratio (CNR) and entrance-surface air dose (ESD) were measured. At 80 kV-Gd, the ESD was reduced by 34% while maintaining the CNR. The results showed that 80 kV-Gd gave the optimal beam quality for anterior-posterior lumbar spine imaging of patients with a standard body type.

Background and aims: Healthcare professionals involved in fluoroscopy-guided endoscopy are occupationally exposed to ionizing radiation. We evaluated whether a patient-immobilization device, MEDO V-Fix®, reduces this exposure.

Methods: Monthly effective and lens equivalent dose were measured for nurses and doctors using personal dosemeters worn inside protective gear. Data from 7 months before and 10 months after device introduction were compared. Additionally a cost-benefit analysis (CBA) of dose reduction was performed.

Results: Monthly effective doses fell in both professions, but neither decline reached statistical significance. By contrast, nurses' mean lens-equivalent dose dropped sharply from 35.0 to 6.5 μSv per procedure (P < 0.01), whereas the reduction in doctors was not significant. In the CBA, assuming a 5-y service life, the benefit-to-cost ratio ranged 1.02-2.72, indicating economic merit.

Conclusions: The MEDO V-Fix significantly reduces the occupational radiation exposure of endoscopy nurses and is a worthwhile investment from a CBA perspective.

Numerical dosimetry for assessments of the absorbed power density (APD) and temperature rise has been conducted using multi-layer skin models, incorporating skin, fat, muscle, and other components, providing a scientific foundation for setting exposure limits. However, the influence of the vasculature on dosimetry outcomes remains underexplored. In this study, we developed a synthetic blood vessel model and integrated it into multi-layer skin models. Electromagnetic computations were performed, followed by steady-state temperature rise evaluations using the Pennes bioheat transfer equation across a frequency range of 3 to 30 GHz. To quantify the effect of vascular modeling on dosimetry results, simulations incorporating vasculature with varying endpoint diameters were compared to those without vasculature. Results showed that the effect of vascular modeling on peak spatial-averaged APD was negligible, and its influence on peak temperature rise was ~8% at 3 GHz, decreasing to less than <3% above 6 GHz. And the effect of the endpoint diameter is marginal. These variations are smaller than those previously reported due to changes in tissue thickness and dielectric or thermal properties. While the effect on peak temperature rise is modest, including vasculature helps refine localized thermal distributions and may inform future improvements in anatomical modeling.