Carstensenhovgaard3921

For energies below 1 MeVee down to ∼100 keVee a closer approximation of the expected FoM for SNM can be attained when using 252Cf as a proxy source or by utilising an 'enhanced' AmBe source with the addition of a further low energy γ ray source.The safe use of radiation sources presupposes the engagement of personnel adequately educated and trained on radiation protection and with the necessary safety culture. This is necessary in order to understand their responsibilities and perform their duties in the safest way for themselves, the public and the patients, where appropriate. The Greek Atomic Energy Commission (EEAE) provides education and training on radiation protection to scientists, technical personnel and members of emergency response teams as well as the recognition of the related programs. To fulfil its role, EEAE implements a strategy on education and training in radiation protection through the development of appropriate programs which take into account the national needs, as well as the national capabilities and resources. In this respect, 65 one and two day training seminars were organised in the period 2011-2017 which were attended by 3126 radiation workers (i.e. medical radiology and nuclear medicine technologists, industrial radiographers and outside workers). The present work demonstrates a quantified assessment of the impact of EEAE training activities on particular categories of radiation workers. The study indicates a reduction in H p(10) values as well as in the corresponding standard deviations of medical radiology technologists, nuclear medicine technologists, and industrial radiographers. A 48% decrease was also observed in the collective dose of medical radiology technologists with cumulative H p(10) values higher than the investigation level. Moreover, an important improvement of specific safety culture indicators, such as the percentage of non-returned personal dosemeters was noticed and presented.Instantaneous dose rate (IDR) measurements were made at the entrances of a number of linac bunkers for a range of beam energies and gantry angles in a large radiotherapy department. The results demonstrate that the IDR does not decrease with distance from the maze entrances according to the inverse square law (ISL), which is commonly used in the design of such bunkers. No simple relationship exists, but a useful guiding principle was found that the IDR at 1 m back from the maze entrance is approximately 50% of that at the entrance itself. This was found to hold with a standard error within 5% across the full extent of the maze entrance by measuring in a grid pattern. The ISL should therefore be used with caution in the design of radiotherapy bunker mazes as it may not provide accurate estimates of the dose in surrounding areas. The results of the grid pattern measurements also indicate that the centre of the maze entrance is the best position to affix passive dosemeters for the purpose of environmental monitoring. This may not always be practical (e.g. if the bunker does not have a door), but factors have been found to correct readings taken elsewhere to the central reading. For instance, if the dosemeter is placed on the wall, the measured dose rate will be equal to 94% ± 8% of the value at the centre of the bunker.As a geometrical format for computational human phantoms, tetrahedral mesh (TM) is known to have significant advantages over polygonal mesh (PM), including higher compatibility with Monte Carlo radiation transport codes, higher computation speed, and the capability of modeling heterogeneous density variation in an organ of the phantom. Ruboxistaurin In the present study, a computer program named POLY2TET was developed to convert the format of computational human phantoms from PM to TM and generate a sample source code or input file, as applicable, for the converted phantom to be used in some general-purpose Monte Carlo radiation transport codes (i.e. Geant4, PHITS, and MCNP6). The developed program was then tested using four existing high-fidelity PM phantoms. The computation speed, memory requirement, and initialisation time of the generated TM phantoms were also measured and compared with those of the original PM phantoms in Geant4. From the results of our test, it was concluded that the developed program successfully converts PM phantoms into the TM format. The organ doses calculated using the generated TM phantom for the three Monte Carlo codes all produced essentially identical dose values to those for the original PM phantoms in Geant4. The comparison of computation speed showed that compared to the original PM phantoms in Geant4, the TM phantoms in the three Monte Carlo codes were much faster in transporting the particles considered in the present study, i.e. by up to ∼2600 times for electron beams simulated in PHITS. The comparison of the memory requirement showed that the TM phantoms required more memory than the original PM phantoms, but, except for MCNP6, the memory required for the TM phantoms was still less than 12 GB, which typically is available in personal computers these days. For MCNP6, the required memory was much higher, i.e. 60-70 GB.The lunar surface is directly and continuously exposed to Galactic Cosmic ray (GCR) particles and Solar energetic particles (SEPs) due to the lack of atmosphere and lunar magnetic field. These charged particles interact with the lunar surface materials producing secondary radiations such as neutrons and gamma rays. In a departure from precise GCR and SEP data, we estimated the effective dose equivalent at the lunar surface and in a lunar lava tube in this paper by using PHITS, a Monte Carlo simulation tool. The effective dose equivalent due to GCR particles at the lunar surface reached 416.0 mSv yr-1 and that due to SEPs reached 2190 mSv/event. On the other hand, the vertical hole of the lava tube provides significant radiation protection. The exposure by GCR particles at the bottom of the vertical hole with a depth of 43 m was found to be below 30 mSv yr-1 while inside a horizontal lava tube, the value was less than 1 mSv yr-1 which is the reference value for human exposure on the Earth. We expect that the lunar holes will be useful components in the practical design of a lunar base to reduce radiation risk and to expand mission terms.