Radiation protection dosimetry最新文献

Soil samples were collected from vegetable agricultural areas in and around Addis Ababa, and their levels of radioactivity were measured. Gamma spectrometry with high-purity germanium detector was used to quantify radioactivity level. The average concentration of 226Ra, 232Th, and 40K were 32.8 ± 2.1, 62.4 ± 4.4, and 544.3 ± 23.3 Bq kg-1 respectively. The mean values of 232Th and 40K are higher, whereas the value of 226Ra is comparable with world average values. Radiological hazard indices, including radium equivalent activity (Raeq), absorbed dose rate (Dr), outdoor annual effective dose equivalent (Deff), external hazard index (Hex), internal hazard index (Hin), and gamma radiation representative level index (Iγ), were calculated based on the activity concentration of 226Ra, 232Th and 40K. The mean values were 163.9 Bq kg-1, 78.7 nGy h-1, 0.10 mSv y-1, 0.44, 0.53, and 0.60 respectively. All indices are lower than global recommended limit values. These results revealed that radiation hazard due to radionuclides in the soil of the study area is insignificant.

Despite the growing use of dose management systems (DMSs), there is limited guidance on their optimal setup. This study aims to fill this gap by outlining the process followed to integrate "DOSE" (Qaelum NV, Belgium) DMS within the Cypriot public hospitals. DOSE was connected to the available central PACS, followed by a thorough data and functioning validation. A preliminary study was also conducted to assess the DOSE's ability to establish typical dose values in diagnostic radiography. Overall, over 70 x-ray units were configured. For some connections, it was necessary to first adjust the unit's DICOM attributes or to utilise the DICOM coercion technique. The DICOM image header was sometimes preferred over the DICOM RDSR, as the chosen data source. This study underscored the importance of understanding the equipment's technical capabilities for a successful DMS integration, while personnel with expertise in diagnostic radiology and the IT aspects of medical physics proved to have a vital role in the process. The pilot study showed that DOSE is an effective tool for establishing typical dose values and assessing compliance with relevant dose levels.

This paper presents a new method for correcting the contribution of scattered radiation to the measurement of 99mTc internal activity in nuclear medicine patients using gamma cameras. So, this study aims to derive scattering correction factors by Monte Carlo simulation for anterior and posterior count rates (${I}_{mathrm{A}}$ and ${I}_{mathrm{P}}$) in the conjugate view method, enabling more precise estimation of activity A(t) compared to traditional trapezoidal and triangular approximations. The new approach eliminates the need to use photopeak for determining the fraction of scattered photons. Our results showed differences of <3% with respect to the real activity and 11% for the trapezoidal and triangular approaches.

In recent years, scientific communities have been concerned about the potential health effects of periodic electromagnetic field exposure (≤1 h/d). The objective of our study is to determine the impact of extremely low-frequency pulsed electromagnetic fields (ELF-PEMF) (1-3 mT, 50 Hz) on mouse fibroblast (red fluorescent protein (RFP)-L929) cells and adult Wistar rats to gain a comprehensive understanding of biological effects. We observed that RFP-L929 exhibits no significant changes in cell proliferation and morphology but mild elevation in aspartate aminotransferases, alanine aminotransferases, total bilirubin, serum creatinine, and creatine kinase-myocardial band levels in ELF-PEMF exposed groups under in vitro and in vivo conditions. However, the histological examination showed no significant alterations in tissue structure and morphologies. Our result suggests that 50-Hz ELF-PEMF exposure (1-3 mT, 50 Hz) with duration (<1 h/d) can trigger mild changes in biochemical parameters, but it is insufficient to induce any pathological alterations.

This article analyzes the external occupational radiation exposure distribution and trends among radiation workers in Jiangsu Province. The results show that the total annual collective effective dose for radiation workers in Jiangsu Province from 2019 to 2022 was 24.82 person·Sv, with an average annual effective dose of 0.34 mSv over the 4-y period. The average annual effective dose exhibited an initial increase followed by a subsequent decrease, with statistically significant differences (P < .001) between different years. In the medical uses, nuclear medicine and interventional radiology had higher average annual effective doses compared to other categories, at 0.42 and 0.38 mSv, respectively (P < .05). In industrial applications, accelerator operation and industrial testing workers had higher average annual effective doses compared to others, at 0.32 and 0.31 mSv, respectively (P < .001). Among different levels of medical institutions, secondary hospitals had the highest average annual effective dose (0.38 mSv, P < .001). Overall, the average annual effective dose for radiation workers in Jiangsu Province remained relatively low from 2019 to 2022, meeting national standards. However, special attention should still be given to radiation workers in nuclear medicine, interventional radiology, industrial testing, and accelerator operation.

Radiation protection in dental radiography can be achieved by adjusting the image field size, exposure, and filtration parameters, and using protective lead shields. The aim of this study is to assess the radiation dose delivered to the thyroid in a phantom irradiated by an orthopantomogram (OPG) system using Geant4 simulation toolkit. Recently, researchers have been trying to find an alternative material to the lead thyroid shield so that the OPG image has minimal metal artifacts. In this study, several materials were introduced as alternatives to lead thyroid shields. The results showed that Pb, Bi, Bi2O3, stainless steel, polyurethane-Bi2O3 (50%-50% mixture), and polyurethane-W (50%-50% mixture) shields provide a thyroid dose reduction of up to 12.0%, 12.3%, 12.0%, 11.6%, 11.8%, and 12.0%, respectively. For the truncated thyroid shields, these values are up to 10.5%, 10.3%, 10.3%, 9.80%, 10.0%, and 10.1%, respectively. Therefore, Bi and Bi2O3 can be suitable alternatives to lead thyroid shields.

Surface contamination monitors are used intensively in many facilities, like in the nuclear medicine departments for clearance measurements and decontamination and in decommissioning of nuclear installations. For a reliable use, all surface contamination monitors should have a valid calibration with traceability to the international standards. A comparison exercise for calibrations in terms of efficiency in 2π steradian for surface contamination monitors was organized between five dosimetry calibration laboratories, members of EURAMET (The European Association of National Metrology Institutes). Four β-beta radionuclide sources, Sr-90, Cl-36, Cs-137, Co-60, and one α-alpha source, Am-241, were used for calibrations during this exercise. Two transfer surface contamination monitors, one Canberra SABG 100 and one Berthold LB 124 with 100 cm2 and 343 cm2 effective area, respectively, were used. The monitors were circulated between the partners and were periodically returned to the pilot laboratory for stability checks. The efficiencies in 2π steradian measured by the participants do not fully agree for all sources and both detectors despite the fact that all laboratories used similar types of surface contamination sources and had proper traceability to primary standards for surface emission rate measurements. As no evident difference in measurements of surface emission rates is expected between the primary standard laboratories that calibrated the sources, it is very probable that the observed differences are mainly due to the calibration procedures used by each laboratory and that the measurement uncertainties of efficiency in 2π steradian are underestimated. This report presents the results of this pilot comparison for calibration of surface contamination monitors and stresses the need to organize similar generalized exercises. This report also identifies some gaps in procedures for calibration of surface contamination monitors.

We investigated the neutron dose estimation for the triage of personnel involved in criticality accidents by conducting 24Na measurements via the whole-body measurement method. For a case study, we examined the September 1999 Japan Nuclear Fuel Conversion Co. criticality accident (internationally known as "the Tokaimura accident"). We investigated the neutron-induced radionuclides produced in worker C's body due to the irradiation of the primary pulse. A total of 87 radionuclides were identified, with activities ranging from 1.3 × 10-19 Bq to 6.9 × 106 Bq for worker C by Monte Carlo simulations. The radionuclide with the highest activity was revealed by calculation results: 28Al (t1/2 = 2.2 min) 6.9 × 106 Bq. The specific activity of 38Cl reached a level that was three times that of 24Na. These radionuclides would severely affect the 24Na measurement in the whole-body measurements performed in the immediate post-accident period. Spectrometry would be preferable for determining 24Na specific activities by whole-body measurements at accident sites.

The present work describes the results for the bilateral comparison between the Secondary Standards Dosimetry Laboratories of the Instituto Nacional de Investigaciones Nucleares (SSDL-ININ), Mexico, and the pilot laboratory, the Centro de Protección e Higiene de las Radiaciones (SSDL-CPHR), Cuba, for the realization of the air kerma (${boldsymbol{K}}_{boldsymbol{a}}$) quantity to: (i) diagnostic X-ray (DXR) IEC 61267:2005 beam qualities: RQR 5 RQR 9, RQT 8, and RQT 9 and (ii) radiation protection (RP) ISO 4037:2019 X-ray beam qualities: N60, N100, and W60, as well S-Cs for gamma radiation. The matched and characterized reference fields are realized at SSDL-ININ with a Toshiba E7252FX X-ray tube. In all cases, the ${boldsymbol{K}}_{boldsymbol{a}}$ measurements are traceable to PTB, except for S-Cs, traceable to ININ. The SSDL-CPHR realizes its reference radiation beam qualities also as matched reference fields with a Pantak HF160C X-ray tube. For the S-Cs beam quality, the CPHR uses a Buchler OB6 irradiator; the ININ, a Siemens Cesagammatron. The transfer ionization chambers calibrated in the RQR and RQT qualities are an Exradin A650/DO70312; for the RQT qualities for CT, a PTW 30009/0655 and RC3CT/9217 were calibrated; and for the RP X-ray qualities, the Exradin A650/DO70312 and a PTW 32002/073 were calibrated. The ratio ${boldsymbol{R}}_{boldsymbol{k}}$ of the resulting calibration coefficients ${boldsymbol{N}}_{{boldsymbol{K}}_{boldsymbol{a}}}$ of each SSDL of the RQR qualities are consistent within the $boldsymbol{U}left(boldsymbol{k}=mathbf{2}right)%$ ≤ 2.3%; for the RQT qualities, the differences are less than the $boldsymbol{U}left(boldsymbol{k}=mathbf{2}right)%$ ≤ 3.6%; and for the RP X-ray qualities, within the order of $boldsymbol{U}left(boldsymbol{k}=mathbf{2}right)%$ ≤ 3.5%. For the S-Cs quality, the ${boldsymbol{R}}_{boldsymbol{k}}$ is in the order of $boldsymbol{U}left(boldsymbol{k}=mathbf{2}right)$ ≤ 3.0%. It should be noted that the ININ U's are generally larger due to the failure of the ${boldsymbol{k}}_{boldsymbol{TP}}$ correction factor, a brief discussion is given here. The ${boldsymbol{E}}_{boldsymbol{n}}$ score from ISO 17043 provides statistical support to this comparison.

In this article, the submersion dose due to a radioactive cloud of pollutants was evaluated at short downwind distances from an emission stack. The atmospheric transport of contaminants was modelled using the Gaussian plume model (GPM). The algorithm for dose computation and its hypotheses were analysed. Two relevant issues were discussed: the semi-infinite cloud approximation used for pre-calculated dose conversion factors and the lack of a radiation transport model for dose computation outside the radioactive cloud. The GPM-based software HotSpot and GENII V2.10 and a FLUKA Monte Carlo GPM implementation were compared in a scenario characterized by a low release height and two different simplified atmospheric conditions. Compared to FLUKA, HotSpot and GENII V2.10 results showed a significant dose overestimation inside the plume. Moreover, in extremely stable meteorological conditions, only the Monte Carlo code could detect the ground-level dose contribution from an overhead plume.