G-M 계수관과 137Cs 선원을 이용한 납 반가층의 실험적 연구

권대철,동경래 (사)한국방사선산업학회 2016 방사선산업학회지 Vol.10 No.3

HVL (half-value layer) of lead was measured experimentally using a lead and 137Cs (370 kBq) source and a G-M counter in which is used a lot of material for shielding HVL measured. 137Cs in holder to 10 cm and start measuring the radiation. Continue addition of lead of the lead thickness of 1 mm one by one to continue the measurement. By measuring four times the natural radiation of 100 seconds and records the count value and the average rate to be displayed on the meter. Background radiation was a 4 times a count rate and the average 108 (100 s-1) as a result of measuring the average measurement, the standard deviation was determined to be 1.08 (s-1). An increase in the thickness of lead initial count rate starting from 920 (N) count rate is decreased with increase in the thickness of lead. Net counting rate, starting with the initial 8.12 (s-1) showed a decrease with increasing thickness, the standard deviation of the results was decreased from 0.303 (s-1) to 0.196 (s-1). Net counting rate is reduced to obtain the result that each half thickness of nappan about 7 mm. Was reduced similarly to the exponential function graph correlation coefficient (R2) was found to be 0.9869. Half-value layer which is the initial net counting rate 7.514 (s-1) is a half the 7 mm to 3.757 (s-1). In conclusion, it was confirmed the theoretical HVL of lead 7.19 mm and experimentally measured results matched the measured HVL 7 mm.

Evaluation of Gamma-Ray Attenuation Parameters for Some Materials

Amal A. El- Sawy 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.11

In the present study, the linear attenuation coefficient and mass attenuation coefficient have been calculated at energy range of 0.8MeV, 1MeV, 3Mev, 5MeV and 7MeV. The mass attenuation Coefficient μm has been calculated analytically for Iron material Fe (ρ= 7.87 g/cm3) and developed material lead Pb (ρ= 11.3 g/cm3) at photon energies [0.8 MeV to 7 MeV] using X-Com computer code. The obtained results were compared with the calculated values. The linear attenuation Coefficient μ has been calculated, its variations with photon energy were plotting. The Comparison between two materials Iron and Lead were also studied. The obtained result shows that μ and μm depends on the photon energy, density of the materials and atomic number. From this study we notice that the values of μm and μ of Lead material is greater than Iron material and also the values are decreasing with increasing the photon energy. The half value layer (HVL) and tenth value layer (TVL) of two studied materials were calculated at photon energy range of 0.8 MeV, 1MeV, 5MeV and 7MeV. The relation between this equation Ln (Io/I) and the thickness of material were calculated, so the curves show that the relation of Ln (Io/I) of Iron and Lead materials is increasing with the increasing of material thickness and the relation gives the straight line, also the comparison of this relation for Lead material is higher than Iron material. This study can also be utilized to improve the effectiveness of radiation shielding by using the developed shielding material.

Reference X-ray Irradiation System for Personal Dosimeter Testing and Calibration of Radiation Detector

Lee, Seung Kyu,Chang, Insu,Kim, Sang In,Lee, Jungil,Kim, Hyoungtaek,Kim, Jang-Lyul,Kim, Min Chae The Korean Association for Radiation Protection 2019 방사선방어학회지 Vol.44 No.2

Background: In the calibration and testing laboratory of Korea Atomic Energy Research Institute, the old X-ray generator used for the production of reference X-ray fields was replaced with a new one. For this newly installed X-ray irradiation system, beam alignment as well as the verification of beam qualities was conducted. Materials and Methods: The existing X-ray generator, Phillips MG325, was replaced with YXLON Y.TU 320-D03 in order to generate reference X-ray fields. Theoretical calculations and Monte Carlo simulations were used to determine initial filter thickness. Beam alignment was performed in three steps to deliver a homogeneous radiation dosage to the target at different distances. Finally, the half-value layers were measured for different X-ray fields to verify beam qualities by using an ion chamber. Results and Discussion: Beam alignment was performed in three steps, and collimators and other components were arranged to maintain the uniformity of the mean air kerma rate within ${\pm}2.5%$ at the effective beam diameter of 28 cm. The beam quality was verified by using half-value layer measurement methods specified by American National Standard Institute (ANSI) N13.11-2009 and International Organization for Standardization (ISO)-4037. For each of the nine beams than can be generated by the new X-ray irradiation system, air kerma rates for X-ray fields of different beam qualifies were measured. The results showed that each air kerma rate and homogeneity coefficient of the first and second half-value layers were within ${\pm}5%$ of the recommended values in the standard documents. Conclusion: The results showed that the new X-ray irradiation system provides beam qualities that are as high as moderate beam qualities offered by National Institute of Standards and Technology in ANSI N13.11-2009 and those for narrow-spectrum series of ISO-4037.

50-300 keV X-ray Transmission Ratios for Lead, Steel and Concrete

Tae Hwan Kim,Kum Bae Kim,Geun Beom Kim,Dong Wook Kim,Sang Rok Kim,Sang Hyoun Choi Korean Society of Medical Physics 2022 의학물리 Vol.33 No.4

The number of facilities using radiation generators increases and related regulations are strengthened, the establishment of a shielding management and evaluation technology has become important. The characteristics of the radiation generator used in previous report differ from those of currently available high-frequency radiation generators. This study aimed to manufacture lead, iron, and concrete shielding materials for the re-verification of half-value layers, tenth-value layers, and attenuation curve. For a comparison of attenuation ratio, iron, lead, and concrete shields were manufactured in this study. The initial dose was measured without shielding materials, and doses measured under different types and thicknesses of shielding material were compared with the initial dose to calculate the transmission rate on 50-300 kVp X-ray. All the three shielding materials showed a tendency to require greater shielding thickness for higher energy. The attenuation graph showed an exponential shape as the thickness decreased and a straight line as the thickness increased. The difference between the measurement results and the previous study, except in extrapolated parts, may be due to the differences in the radiation generation characteristics between the generators used in the two studies. The attenuated graph measured in this study better reflects the characteristics of current radiation generators, which would be more effective for shield designing.

6 MV X-선 빔의 등가에너지 결정

김종언(Jong-Eon Kim),박병도(Byung-Do Park) 한국방사선학회 2016 한국방사선학회 논문지 Vol.10 No.8

본 연구의 목적은 실험으로 6 MV X-선 빔의 등가에너지를 결정하는 데 있다. 6 MV X-선 빔에 대한 납 의 반가층은 전리함을 사용하여 측정하였다. 선감쇠계수는 측정된 반가층을 사용하여 계산하였다. 그리고 질량감쇠계수는 납의 밀도로 선감쇠계수를 나누어 얻었다. 얻어진 질량감쇠계수의 등가에너지는 미국표준 기술연구소에서 주어진 납의 광자에너지 대 질량감쇠계수 자료를 사용하여 결정하였다. 그 결과로서, 6 M V X-선 빔에 대한 등가에너지는 1.61 MeV로 결정되었다. 이 등가에너지는 Reft가 보고한 것 보다 약 30% 낮게 결정되었다. 그 원인은 납 감쇠기 사이의 공기공동의 존재에 기인한 것으로 추정된다. The purpose of this study is to determine the equivalent energy of a 6MV X-ray beam in the experiment. The half-value layer (HVL) of lead for the 6 MV X-ray beam was measured using an ionization chamber. The linear attenuation coefficients were calculated with HVL. And, the mass attenuation coefficient was obtained by dividing the linear attenuation coefficient by the density of lead. The equivalent energy of mass attenuation coefficient was determined using the photon energy versus mass attenuation coefficient data of lead given by National Institute of Standards and Technology (NIST). In conclusion, the equivalent energy of the 6 MV X-ray beam was determined to be 1.61 MeV. This equivalent energy was determined to be about 30% lower than reported by Reft. The reason is presumed to be due to the presence of an air cavity between the lead attenuators.

Photon Shielding Characterization of a Modified Titania-Bismuth-Borotellurite Glass System for Medical Applications

Hossam Donya,Salem Sulami 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.11

Shielding against ionizing radiation is considered a crucial issue for the radiation safety of patients and workers at radiology centers. For this purpose, the shielding effectiveness of a modified titania-bismuth-borotellurite (TiO2-Bi2O3-B2O3-TeO2) glass system at diagnostic energy ranges was investigated. This glass system is characterized by the high density of its components and its non-toxicity, which have given it an outstanding reputation in radiation shielding. A comparison of shielding characteristics between different compositions of the mentioned glass system and shielding materials frequently used at radiology centers, including lead glass and ordinary concrete, is implemented. The computational program WinXCom was utilized to evaluate the mass attenuation coefficients (μ/ρ)m of the glass compositions, lead glass and ordinary concrete. The incident diagnostic X-ray photon beams used in imaging tools such as computed tomography (CT), dental imaging, general radiography and mammography were employed at average energies of 60, 40, 30, and 20 keV, respectively. Additional shielding parameters, such as half-value layers (HVLs) and effective atomic numbers (Zeff ), were also computed. The results revealed that among the materials tested, the glass system with high bismuth-oxide content in (i.e., the 30Te sample) is the best shielding material for different diagnostic imaging tools. Such a transparent glass system could be advantageous, as it is considered a green and environmentally friendly shielding material that can replace undesirable toxic lead glass and ordinary concrete, which occupies a large amount of space at radiology centers.

Radiation shielding properties of weathered soils: Influence of the chemical composition and granulometric fractions

Pires Luiz F. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.9

Soils are porous materials with high shielding capability to attenuate gamma and X-rays. The disposal of radionuclides throughout the soil profile can expose the living organisms to ionizing radiation. Thus, studies aiming to analyze the shielding properties of the soils are of particular interest for radiation shielding. Investigations on evaluating the shielding capabilities of highly weathered soils are still scarce, meaning that additional research is necessary to check their efficiency to attenuate radiation. In this study, the radiation shielding properties of contrasting soils were evaluated. The radiation interaction parameters assessed were attenuation coefficients, mean free path, and half- and tenth-value layers. At low photon energies, the photoelectric absorption contribution to the attenuation coefficient predominated, while at intermediate and high photon energies, the incoherent scattering and pair production were the dominant effects. Soils with the highest densities presented the best shielding properties, regardless of their chemical compositions. Increases in the attenuation coefficient and decreases in shielding parameters of the soils were associated with increases in clay, Fe2O3, Al2O3, and TiO2 amounts. In addition, this paper provides a comprehensive description of the shielding properties of weathered soils showing the importance of their granulometric fractions and oxides to the attenuation of the radiation

Determination of the Inherent Filtration of the 320 kV X-ray Tube at KHNP-CRI by HVL Measurement

Hyeongjin Kim,Moonhyung Cho 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

According to ISO 4037, the thickness of the inherent filtration for the radiation qualities L-40 to L- 240, N-40 to N-400, W-60 to W-300 and H-80 to H-400 shall be equivalent to 4 mm Al for matched reference radiation fields or adjusted as far as possible to 4 mm Al for characterized reference radiation fields. And for matched reference fields, the tube window must be made of beryllium and its thickness should not exceed 10 mm. In the case of characterized reference fields, the thickness of the beryllium window should not exceed 10 mm, but it is acceptable to use an aluminum window with a maximum thickness of 1.5 mm. 320 KV X-ray tube installed at KHNP-CRI has been designed to equipped with a 3 mm Be for tube window and an additional 4 mm Al to obtain a total inherent filtration equivalent to that of 4 mm Al. In the previous study, the inherent filtration of 320 kV X-ray tube at KHNP-CRI has been verified by MCNP simulation. However, the ISO standards suggest a method for determining the thickness of the inherent filtration by half-value layer (HVL) measurement and spectrometry. In this regard, the inherent filtration was reassessed using HVL measurement. To determine the inherent filtration, 1st HVL of the beam generated by the tube at a tube potential 60 kV was measured. The measurements were conducted with a calibrated spherical ionization chamber (model A3, Exradine) placed at a distance of 1 m from the target, at the center of the radiation field size. The X-ray tube current was set to 2 mA. The thickness of aluminum absorbers was gradually adjusted in subsequent measurements until approached the 1st HVL. 1st HVL were estimated using the linear regression equation computed with the current values for the thickness of the absorbers. As a results, the thickness of the 1st HVL was estimated as 2.845 mm Al. According to the correlation between the inherent filtration and 1st HVL suggested in ISO standard, the value of the inherent filtration was deduced as 4.25 mm Al that is rounded to the nearest 0.05 mm by interpolation. Further studies on the effects of the inherent filtration thickness determined in this study will be conducted.

Investigation of the suitability of new developed epoxy based-phantom for child's tissue equivalency in paediatric radiology

Haluk Yücel,Aziz Safi 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12

In this study, tissue equivalency (TE) of a newly developed epoxy-based phantom to 3e5 years child'stissue was investigated in paediatric energy range. Epoxy-based TE-phantoms were produced at differentglandular/adipose (G/A) ratios of 17/83%, 31/69%, 36/64% and 10/90%. A procedure was developed inwhich specific amounts of boron, calcium, magnesium, sulphur compounds are mixed with epoxy resin,together with other minor substitutes. In paediatric energy range of 40e60 kVp half-value layer (HVL)values were measured and then Hounsfield Units (HU) were determined from Computed Tomography(CT) scans taken in the X-ray energy range of 80-120kVp. It is found that radiation absorptionproperties of these phantoms in terms of the measured HVL values related to linear attenuation coefficients (m) are very well mimicking a 3 years child's soft tissue in case a ratio of 10/90%G/A. Additionally, the HU values of phantoms were determined from the CT scans. The HU ¼ 47.8 ± 4.8 value wasfound for the epoxy-based phantom produced at a ratio of 10/90%G/A. The obtained HVL and HU valuesalso support the suitability of the new epoxy based-phantom produced at a ratio of 10/90%G/A for asatisfactory mimicking a 3 years child's soft tissue by 5%. Thus they can have a potential use to performthe quality controls of medical X-ray systems and dose optimization studies

Radiation parameterizations and optical characterizations for glass shielding composed of SLS waste glass and lead-free materials

Khazaalah Thair Hussein,Mustafa Iskandar Shahrim,Sayyed M.I. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.12

The novelty in the present search, the Soda-Lime-Silica (SLS) glass waste to prepare free lead glass shielding was used in order to limit the accumulation of glass waste, which requires extensive time to decompose. This also saves on the consumption of pure SiO2, which is a finite resource. Furthermore, the combining of BaO with Bi2O3 into a glass network leads to increased optical properties and improved attenuation. The UVeVisible Spectrophotometer was used to investigate the optical properties and the radiation shielding properties were reported for current glass samples utilizing the PhysX/PDS online software. The optical property results indicate that when BaO content increases in glass structure, the Urbach energy DE, and refractive index n increases while the energy optical band gap Eopt decreases. The result of the metallisation criteria (M) revealed that the present glass samples are nonmetallic (insulators). Furthermore, the radiation shielding parameter findings suggest that when BaO was increased in the glass structure, the linear attenuation coefficient and effective atomic number (Zeff) rose. But the half-value layer HVL declined as the BaO concentration grew. According to the research, the glass samples are non-toxic, transparent to visible light, and efficient radiation shielding materials. The Ba5 sample is considered the best among all the samples due to its higher attenuation value and lower HVL and MFP values, which make it a suitable candidate as transparent glass shield shielding.