Greek Atomic Energy Commission

PurposeTo provide beam quality correction factors (kQ,Qo) for detectors used in 192Ir brachytherapy dosimetry measurements.Materials and MethodsTen detectors were studied, including the PTW 30013 and Exrading12 Farmer large cavity chambers, seven medium (0.1–0.3 cm3) and small (< 0.1 cm3) cavity chambers, and a synthetic microdiamond detector. The kQ,Qo correction factors were calculated at distances from 1 to 10 cm away from an 192Ir source, using the EGSnrc Monte Carlo (MC) code. All detectors were calibrated in a 60Co 10 × 10 cm2 reference field provided by standard calibration laboratories. The impact of the central electrode, stem and wall on the detectors’ responses in 192Ir photon energies was investigated. An experimental procedure was additionally applied for dose measurements around a microSelectron‐v2 192Ir high dose rate (HDR) brachytherapy source using a motorized water phantom.ResultsFarmer chambers underestimated the dose near the source due to signal volume averaging effects, resulting in kQ,Qo values ranging from 1.177 and 1.317 at 1 cm, decreasing with distance to between 0.980 and 1.005 at 10 cm. Small cavity volume detectors should be used close to the source. The kQ,Qo for the studied small and medium cavity volume detectors were found to be close to unity (within 1.3%), showing also a small dependence on source‐to‐detector distance, except for ion chambers containing high‐Z materials in their construction. The presence of high‐Z materials caused an overresponse in these detectors, resulting in kQ,Qo values ranging from 0.950 at 1 cm to 0.729 at 10 cm away from the source. A dose rate constant of (1.114 ± 0.023)cGyh−1U−1 was found in agreement with the literature (within 0.5%).ConclusionskQ,Qo values were calculated for dose measurements around 192Ir brachytherapy sources. Farmer chambers should be preferred for measurements at increased distances, whereas small or medium cavity volume detectors, not containing high‐Z materials, should be used close to the source.

Abstract The Greek Atomic Energy Commission (EEAE) is the national regulatory authority, competent for the control, regulation, and supervision in the fields of nuclear energy, nuclear technology, radiological and nuclear safety, and radiation protection. Within its mandate is to assess emergencies in or out of Greece, which may entail radiological risk for the country. To this end, studies based on atmospheric dispersion software, like JRodos, are performed [1]. To validate the performance of the software, EEAE recently participated in a JRodos intercomparison exercise. The exercise was conducted within the Rodos User Group (RUG), and was based on a hypothetical release from a nuclear icebreaker in Danish coastal waters. This work further evaluates its results on the basis of their sensitivity in the parameter of the atmospheric dispersion models. To this end, three atmospheric dispersion models: RIMPUFF [2], LASAT [3], and DIPCOT [4], were applied. Their results were compared in different timesteps in terms of the effective gamma-dose rate at the height of 1 meter. It was found that results tend to differentiate immediately after the release due to the models’ different approaches. However, all models yield similar results at the later phases of the release.

Nanoparticle formation by Spark Discharge Aerosol Generation offers low-cost fabrication of nanoparticles, without the use of chemicals or vacuum. It produces aerosol particles of a few nanometers in size with high purity. In this work, copper-based -CuO (tenorite) and Cu- nanoparticles are produced, characterized and used to modify face mask air filters, achieving the introduction of antibacterial and antiviral properties. A range of characterization techniques have been employed, down to the atomic level. The majority of the particles are CuO (of a few nanometers in size that agglomerate to form aggregates), the remainder being a small number of larger Cu particles. The particles were deposited on various substrates, mainly fiber filters in order to study them and use them as biocidal agents. On face masks, their antibacterial activity against Escherichia coli (E.coli) results in a 100 % decrease in bacteria cell viability. Their antiviral activity on face masks results in a 90 % reduction of the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) viability, 15 minutes post the application of the virus stock solution. This highlights the effectiveness of this approach, its simplicity, its low cost and its excellent environmental credentials.

The European Dosimetry Group has been organising international intercomparisons (ICs) for personal dosemeters on a regular basis. The IC announced in 2020 was postponed to the end of 2020 and the beginning of 2021 due to coronavirus (COVID-19) restrictions. The irradiation plan consisted of nine irradiation setups with five different photon radiation qualities (S-Cs, S-Co, N-150, W-60, W-80) and two different angles of irradiation incidence (0o and 60o). A total of 112 monitoring services from 50 countries with 132 dosimetry systems participated. The present work describes and analyses the individual results for the personal dose equivalent quantities Hp(10) and, if submitted, Hp(0.07) for all participating systems. It also presents the organisational details and the difficulties arising from the COVID-19 crisis during the IC. The statistical results showed a satisfactory performance with the medians of all Hp(10) and Hp(0.07) response values very close to unity. However, there are few individual monitoring services with significant large variations.

Abstract Emission of airborne particulate matter is produced by the industrial processes of metal extraction from electronic waste (e‐waste). These aerosols can transport organic contaminants, such as polyaromatic hydrocarbons (PAHs) and polybrominated biphenyls. These pollutants are proven to have long‐term effects on workers' health. In this work, we characterize aerosol particles and dust deposited from a recycling process of printed circuit boards in a recycling plant. This study also explores the significance of the secondary aerosol sources, and their importance, as an additional burden compared to primary sources. A Scanning Mobility Particles Counter and Sizer (SMPCS) was used to measure the size distributions of ultrafine particles. A Micro‐Orifice Uniform Deposition Impactor (MOUDI) collected aerosol particle samples for chemical analysis. All plant compartments checked are subject to high particulate matter concentrations during work hours. Concentrations of organic pollutants in the machinery compartments do not pose a short or long‐term health risk according to US Occupational Safety and Health Administration (OHSA). The application of the model presented in this work revealed that the accumulation of contaminants in other compartments should be considered in an occupational exposure assessment because it can present an equally important burden to workers’ health.

This study aimed to estimate scattered radiation and its spatial distribution around three cone-beam computed tomography (CBCT) devices, in order to determine potential positions for an operator to stand if they needed to be inside the CBCT room. The following devices were tested: Morita Accuitomo (CBCT1), Newtom Giano HR (CBCT2), Newtom VGi (CBCT3). Scattered radiation measurements were performed using different kVp, mA, and Field of View (FOV) options. An anthropomorphic phantom (NATHANIA) was placed inside the X-ray gantry to simulate clinical conditions. Scattered measurements were taken with the Inovision model 451P Victoreen ionization chamber once placed at fixed distances from each irradiation isocenter, away from the primary beam. A statistically significant (p < 0.001) difference was found in the mean value of the scattered radiation estimations between the CBCT devices. Scattered radiation was reduced with a different rate for each CBCT device as distance was increased. For CBCT1 the reduction was 0.047 μGy, for CBCT2 it was 0.036 μGy, and for CBCT3 it was 0.079 μGy, for every one meter from the X-ray gantry. Therefore, at certain distances from the central X-ray, the scattered radiation was below the critical level of 1 mGy, which is defined by the radiation protection guidelines as the exposure radiation limit of the general population. Consequently, an operator could stay inside the room accompanying the patient being scanned, if necessary.

Natural thermal and mineral therapeutic springs exist all over Greece. A radiological survey has been carried out in the municipality of Edipsos to study the naturally occurring alpha emitter radionuclides, 226Ra and the uranium isotopes. Thirteen thermal spring water samples and six tap water samples which were collected from five locations in the municipality of Edipsos, were analysed and measured by a-spectrometry. The obtained results show that 238U activity varies between 2.8±0.3 and 65.0±5.3 mBq/L in hot springs and between 2.70±0.35 and 10.6±0.9 mBq/L in tap water samples. The 234U/238U activity ratio lying between 1.12±0.17 and 2.12±0.30 indicates enrichment in the 234U concentration that can be explained through its ability to be easily leached from mineral surfaces. The 226Ra activity concentration varies between 3.5±0.4 and 1470±127 mBq/L in hot springs and between 6.5±0.9 and 28.2±2.8 mBq/L in tap water samples. Based on these results the estimated doses in this study are below the recommended dose of 1mSv/y. Highlights A radiological survey was carried out in the thermal springs of Edipsos, one of the most popular spa towns in Greece. Determination of uranium isotopes and 226Ra via a-spectrometry was performed. Low uranium content was a common characteristic for all the samples.