• Nuclear Engineering and Technology
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• 제46권2호
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• pp.217-224
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• 2014

The present work used the efficiency transfer method used to calculate the full energy peak efficiency (FEPE) curves of the (2"*2" & 3"*3") NaI (Tl) detectors based on the effective solid angle subtended between the source and the detector. The study covered the effect of the self attenuation coefficient of the source matrix (with a radius greater than the detector's radius) on the detector efficiency. $^{152}$ An Eu aqueous radioactive source covering the energy range from 121.78 keV up to 1408.01 keV was used. In this study an empirical formula was deduced to calculate the difference between the measured and the calculated efficiencies [without self attenuation] at low and high energy regions. A proper balance between the measured and calculated efficiencies [with self attenuation] was achieved with discrepancies less than 3%, while reaching 39% for calculating values [without self attenuation] due to working with large sources, or for low photon energies.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.818-824
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• 2019

In the present work, we determined the gamma-ray attenuation characteristics of eight different polymers(Polyamide (Nylon 6) (PA-6), polyacrylonitrile (PAN), polyvinylidenechloride (PVDC), polyaniline (PANI), polyethyleneterephthalate (PET), polyphenylenesulfide (PPS), polypyrrole (PPy) and polytetrafluoroethylene (PTFE)) using transmission geometry utilizing the high resolution HPGe detector and different radioactive sources in the energy range 81-1333 keV. The experimental linear attenuation coefficient values are compared with theoretical data (WinXCOM data). The linear attenuation coefficient of all polymers reduced quickly with the increase in energy, at the beginning, while decrease more slowly in the region from 267 keV to 835 keV. The effective atomic number of PVDC and PTFE are comparatively higher than the $Z_{eff}$ of the remaining polymers, while PA-6 possesses the lowest effective atomic number. The half value layer results showed that PTFE ($C_2F_4$, highest density) is more effective to attenuate the gamma photons. Also, the theoretical results of macroscopic effective removal cross section for fast neutrons ($\sum_{R}$) were computed to investigate the neutron attenuation characteristics. It is found that the $\sum_{R}$ values of the eight investigated polymers are close and ranged from $0.07058cm^{-1}$ for PVDC to $0.11510cm^{-1}$ for PA-6.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.647-653
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• 2019

A comprehensive study of photon interaction features has been made for some alloys containing Pd and Ag content to evaluate its possible use as alternative gamma radiations shielding material. The mass attenuation coefficient (${\mu}/{\rho}$) of the present alloys was measured at various photon energies between 81 keV - 1333 keV utilizing HPGe detector. The measured ${\mu}/{\rho}$ values were compared to those of theoretical and computational (MCNPX code) results. The results exhibited that the ${\mu}/{\rho}$ values of the studied alloys are in same line with results of WinXCOM software and MCNPX code results at all energies. Moreover, Pd75/Ag25 alloy sample has the maximum radiation protection efficiency (about 53% at 81 keV) and lowest half value layer, which shows that Pd75/Ag25 has superior gamma radiation shielding performance among the compared other alloys.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.853-859
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• 2019

A comprehensive study of photon interaction features has been made for some alloys containing Pd and Ag content to evaluate its possible use as alternative gamma radiations shielding material. The mass attenuation coefficient (${\mu}/{\rho}$) of the present alloys was measured at various photon energies between 81 keV-1333 keV utilizing HPGe detector. The measured ${\mu}/{\rho}$ values were compared to those of theoretical and computational (MCNPX code) results. The results exhibited that the ${\mu}/{\rho}$ values of the studied alloys are in the same line with results of WinXCOM software and MCNPX code results at all energies. Moreover, Pd75/Ag25 alloy sample has the maximum radiation protection efficiency (about 53% at 81 keV) and lowest half value layer, which shows that Pd75/Ag25 has superior gamma radiation shielding performance among the other compared alloys.

• Journal of Radiation Protection and Research
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• 제42권1호
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• pp.26-32
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• 2017

Background: Ionizing radiation is known to be harmful to human health. The shielding of ionizing radiation depends on the attenuation which can be achieved by three main rules, i.e. time, distance and absorbing material. Materials and Methods: The mass attenuation coefficient, linear attenuation coefficient, Half Value Layer (HVL) and Tenth Value Layer (TVL) of X-rays (32 keV, 74 keV) and gamma rays (662 keV) are measured in Barium compounds. Results and Discussion: The measured values agree well with the theory. The effective atomic numbers ($Z_{eff}$) and electron density (Ne) of Barium compounds have been computed in the wide energy region 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. Conclusion: The mass attenuation coefficient and linear attenuation coefficient for $BaCO_3$ is higher than the $BaCl_2$, $Ba(No_3)_2$ and BaSO4. HVL, TVL and mean free path are lower for $BaCO_3$ than the $BaCl_2$, $Ba(No_3)_2$ and $BaSO_4$. Among the studied barium compounds, $BaCO_3$ is best material for x-ray and gamma shielding.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1483-1488
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• 2017

In order to predict and control the environmental and health impacts of ionizing radiation in environmental sources such as groundwater, it is necessary to identify the radionuclides present. Beta-emitting radionuclides are frequently identified by measuring their characteristic energy spectra. The present work shows that self-attenuation effects from volume sources result in a geometry-dependent shift in the characteristic spectra, which needs to be taken into account in order to correctly identify the radionuclides present. These effects are shown to be compounded due to the subsequent shift in the photon spectra produced by the detector, in this case an inorganic solid scintillator ($CaF_2:Eu$) monitored using a silicon photomultiplier. Using tritiated water as an environmentally relevant, and notoriously difficult to monitor case study, analytical predictions for the shift in the energy spectra as a function of depth of source have been derived. These predictions have been validated using Geant4 simulations and experimental results measured using bespoke instrumentation.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.100-105
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• 2024

In this study, we propose an alternative approach using Artificial Neural Networks (ANN) for determining Mass Attenuation Coefficients (MAC) in various glass systems. This method takes into account the weights of glass compositions, density, and photon energy as input features. The ANN model was trained and tested on a dataset consisting of 650 data points and subsequently validated through a K-fold cross-validation procedure. Our findings demonstrate a high level of accuracy, with R² values ranging from 0.90 to 0.99. Additionally, the model exhibits robust extrapolation capabilities with an R² score of 0.87 for predicting MAC values in a new glass system. Furthermore, this approach significantly reduces the need for costly and time-consuming computations and experiments, making it a potential tool for selecting materials for effective radiation protection.

• 한국방사선학회논문지
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• 제16권6호
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• pp.771-778
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• 2022

이 연구의 목적은 임상에서 AAPM CT 성능 팬텀을 이용한 CT영상 노이즈 정도관리에 사용할 수 있는 물 유효선감쇠계수의 백분율에 의한 노이즈 측정의 방법을 제시하는 데 있다. 120 kVp CT X-선 빔으로 AAPM CT 성능 팬텀을 스캔하여 얻어진 CT영상에서, CT수 직선성 삽입부분의 각 핀과 물에 대하여 평균 CT수를 측정하였다. 유효에너지는 각 핀과 물에 대하여 측정된 평균 CT수와 광자에너지별 선감쇠계수의 선형회귀분석의 상관계수들로부터 가장 큰 상관계수를 갖는 광자에너지로 결정하였다. 그리고 물과 아크릴에 대하여 측정된 평균 CT수와 유효선감쇠계수로부터 대조도 척도는 0.000188 cm^-1 · HU^-1으로 산출되었다. 산출된 대조도 척도, 물 유효선감쇠계수, 그리고 AAPM CT 성능 팬텀에서 고정핀 부분의 물에서 측정된 표준편차를 사용하여, 물 유효선감쇠계수의 백분율에 의한 노이즈 측정값은 100 ~ 300 mAs의 범위에서 0.31 ~ 0.52%를 얻었다.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3441-3449
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• 2023

We determined the radiation shielding properties for 10CaO-xPbO-(90-x) deteriorated silica gel (DSG) glass system (x = 20, 25, 30, 35, 40, and 45 mol.%). The mass attenuation coefficient (MAC) has been estimated at photon energies of 74.23, 97.12, 122, 662, 1173, and 1332 keV using a narrow beam X-ray attenuation and transmission experiment, the XCOM program, and a PHITS simulation. The obtained MAC values were applied to estimate the half value layer (HVL), mean free path (MFP), effective atomic number, and effective electron density. Results show that the MAC value of the studied glasses ranges between 0.0549 and 1.4415 cm²/g, increases with the amount of PbO, and decreases with increasing photon energy. The HVL and MFP values decrease with increasing PbO content and increase with increasing photon energy. The recycled glass, with the addition of PbO content (20-45 mol.%), exhibited excellent radiation shielding capabilities compared to standard barite and ferrite concretes and some glass systems. Moreover, the experimental radiation shielding parameters agree with the XCOM and PHITS values. This study suggests that this new waste-recycled glass is an effective and cost-saving candidate for X-ray and gamma-ray shielding applications.

• Radiation Oncology Journal
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• 제8권1호
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• pp.125-131
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• 1990

방사선조사시 선량분포에 영향을 미치는 여러가지 요소들 중에서 조직불균등성은 선량을 상당히 변화시킨다. 특히, 중뇌강은 여러골조직으로 구성되어 있어 조직 불균등성에 따른 상당한 선랑감쇠가 예상된다. 6 MV X-선 조사후 중두개와에서의 선량분포측정은 LiF TLD 소자를 이용하였으며 같은 측정장소에서, 계산에 의한 예상선량과 실측선량의 비교를 시도하였다. 계산에 의하면, 골조직 1 cm당 예상선량감쇠는 $3.74\%$를 나타내었다. 한편, 골조직을 고려한 예상선량과 실측선량의 차이는 매우 적었으며 $\pm0.21\%$의 오차범위내에서 일치됨을 나타내었다.