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The aim of this study is to improve the characterization and modeling of the radiation field surrounding the Leksell Gamma Knife®-PerfexionTM. The improved characterization of the radiation field enables more accurate shielding calculations to be performed for the areas adjacent to the treatment room. With the aid of a high-purity germanium detector and a satellite dose rate meter, γ -ray spectra and ambient dose equivalent H*(10) data were acquired at various locations in the field of a Leksell Gamma Knife unit in a treatment room at Karolinska University Hospital, Sweden. These measurements were used to validate the results of the PEGASOS Monte Carlo simulation system with a PENELOPE kernel. The levels of the radiation that passes through the shielding of the machine (leakage radiation) are shown to be much lower than what is suggested by various bodies, e.g. the National Council on Radiation Protection and Measurements, to be used when calculating radiation shielding barriers. The results clearly indicate that Monte Carlo simulations may be used in structural shielding design calculations for γ rays from the Leksell Gamma Knife. • A HPGe detector has been used to study the radiation field around the Gamma Knife; • A phase space has been used to study the radiation in the field of the Gamma Knife; • A novel pile-up modeling has been used to compare MC simulations with measurements. [ABSTRACT FROM AUTHOR]

In this research paper, we report on the radiation shielding ability of five newly developed chalcogenide alloys described by the chemical compositions of Ge 20 Sb 6 Te 72 Bi 2 (GTSB1), Ge 20 Sb 6 Te 70 Bi 4 (GTSB2), Ge 20 Sb 6 Te 68 Bi 6 (GTSB3), Ge 20 Sb 6 Te 66 Bi 8 (GTSB4), and Ge 20 Sb 6 Te 64 Bi 10 (GTSB5). The simulation (Monte Carlo) technique is systematically utilized to understand the problem of radiation propagation through the chalcogenide alloys. The maximum deviation between the theoretical values and simulations outcomes for each alloy sample corresponds to circa 0.525, 0.517, 0.875, 0.619, and 0.574% for GTSB1, GTSB2, GTSB3, GTSB4, and GTSB5, respectively. The obtained results indicate that the rapid decline in the value of the attenuation coefficients is mainly due to the main photon interaction process with the alloys for E ≤ 500 keV. Additionally, the charged particle and neutron transmission properties are assessed for the involved chalcogenide alloys. Comparing the MFP and HVL with those of the conventional shielding glasses and concretes, the present alloys are good photon absorbers and they could be used to replace some conventional shields in radiation protection applications. • High Te content chalcogenide alloys were reported for radiation shielding applications. • Monte Carlo method was successfully applied in the design of vacuum system for radiation propagation. • The optimum thickness for narrow beam transmission geometry is less than 0.1 cm. • GTSB5 alloys can conveniently replace the traditional materials. [ABSTRACT FROM AUTHOR]

Abstract: The International Commission on Radiological Protection (ICRP) published the new recommendations 2007 on radiological protection. International Atomic Energy Agency (IAEA) is also under process in revising its International Basic Safety (BSS). According to revision of the ICRP recommendations and BSS, the Korean government plans to implement those changes. In the 2007 ICRP recommendations, there are some new concepts, principles and quantities. Based on the study carried out by Korea Institute of Nuclear Safety (KINS) so far, the following points are identified as major areas that need further in-depth review and consideration for the implementation of the ICRP 2007 recommendations into Korean radiation protection laws and regulations; changes in the radiation risk factors, radiation weighting factors and tissue weighting factors, maintenance of the ICRP 60 dose limits, practical application of the dose constraints and determination of the reference levels in many source to individual exposure relationships, change from process-based system to exposure situation-based system, strengthening of the principle of optimization in all exposure situations, system of radiation protection for the environment, practical application of the exclusion and exemption principles, active participation of the stakeholders, changes in glossary etc. The study for the implementation of the ICRP 2007 recommendations into national legislations will be conducted till the end of 2012. In the meantime, draft regulations will be developed and the possible impact on the nuclear industry will also be analyzed and active involvement of the stakeholders including licensees will be encouraged in the entire process. The final draft of the revised laws and regulations will be issued in the early of 2013 and the formal legislation process of this final draft will commence in due course. [Copyright &y& Elsevier]

Abstract: The existence of a traceable relationship between national regulatory standards and international recommendations is important especially when the national regulations have to be justified and explained to the public and their representatives. Guidance on various types of radiological levels in environmental media related to public exposure has been provided by the relevant international organizations, constituting a basis for the development of national regulations. However, international standards need to be clear and based on solid technical criteria. In their preparation, consideration should be given to the implications for different countries, and the differences that exist between them, for example, in social, economic and climatic aspects. [Copyright &y& Elsevier]

This study aimed to simulate the X-ray Irradiator narrow-spectrum series and compare the results with experimental and recommended values in ISO standards. X-Ray beam qualities of N-40 to N-300 were established experimentally at the national Secondary Standard Dosimetry Laboratory (SSDL) of Morocco in purpose of calibrating radiation protection- level. The variations between the first half-value layer (1st HVL) and the second (2nd HVL) for experimental were within 5%. Also, homogeneity coefficients h were mostly between 0.75 and 1 according to ISO. GAMOS Monte Carlo code was used to simulate the radiation quality of narrow-spectrum series between N-40 to N-150. All 1st HVL, 2nd HVL, and h simulation values were compare with experimental and ISO values. In MC codes and GAMOS, there is no direct way to generate the X-ray spectrum if we do not have details of the X-ray tube geometry, dimensions and materials. Therefore, Institute of Physics and Engineering in Medicine report number 78 was used to generate the X-ray spectrums in purpose to test this method accuracy. The simulation results for the 1st HVL and 2nd HVL showed a good agreement with experimental data and with ISO 4037–1:1996 given values. Also, the comparison results showed that most of the homogeneity coefficients are within the ISO standard range. • Narrow series beam quality was established at National SSDL of Morocco. • Beam quality of NS were simulate using GAMOS/GEANT4. • IPEM 78 spectrum data were used to generate x-ray spectrums. [ABSTRACT FROM AUTHOR]

In this work, an experimental study of the radiation beam characteristics of the photon beams produced by commercial irradiator that uses a single collimated 137Cs source is performed. A set of lead attenuators are placed at the exit window of the irradiator to vary the air Kerma that is required to cover the instrument scales at a particular calibration distance. The results strongly enhance the findings of previous studies that a single source with appropriate attenuation and collimation is a practical solution for calibration laboratories with an acceptable overall accuracy. [Copyright &y& Elsevier]