Photon Attenuation Coefficients Research Articles

A Comprehensive study on the γ-ray shielding performance of Al–Cu–PbO alloy: Experimental and simulation studies

The importance of radiation shielding is increasing due to the expanding areas exposed to radiation emissions. As a result, there is a crucial need to develop metal alloys and composites that demonstrate exceptional capabilities in absorbing neutron and gamma rays for effective radiation protection. The major purpose of this study is to determine the gamma photon attenuation coefficients of several Al–Cu–PbO alloys for radiation detection applications. The transmission geometry technique was used to calculate experimental mass attenuation coefficients at photon energies ranging from 0.662 to 1.33 MeV. To corroborate the experimental results, the mass attenuation coefficients for the alloys under consideration were calculated and confirmed by simulation using the MCNP5 method. The study analyzes the possibility of these alloys as alternative materials for nuclear radiation shielding applications.

Novel starch–tungsten (VI) oxide biocomposites: Preparation, characterization, and comparisons between experimental and theoretical photon attenuation coefficients

This study synthesized biocomposites containing starch and WO3 at varying ratios of 10 %, 20 %, 30 %, 40 %, and 50 % and assessed their thermal and radiation-shielding properties. These biocomposites were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction (XRD) analysis, particle-size distribution assessments, scanning electron microscopy–energy dispersive X-ray spectroscopy, and thermogravimetric analysis–differential thermogravimetry measurements. Furthermore, the linear attenuation coefficients of the biocomposites were experimentally measured using an NaI(Tl) gamma spectrometry system and theoretically computed using XCOM and GAMOS simulations for comparisons. The XRD and particle-size distribution profiles of the WO3.2H2O powder, respectively, demonstrated evident diffraction peaks and favorable pore-size distributions. Morphological characterizations revealed that the WO3 particles were homogeneously dispersed throughout the starch matrix without any agglomeration. Comparisons of the thermal degradation rates revealed that the pure starch and starch +50%WO3 biocomposite began decomposing at approximately 200°Cand 300 °C, respectively, indicating that increasing WO3 proportions enhanced thermal stability. Furthermore, the starch +50%WO3 biocomposite demonstrated the highest experimental linear attenuation coefficient, with a value of 0.2510 ± 0.0848 cm−1 at a gamma energy of 662 keV. Meanwhile, XCOM and GAMOS simulations revealed theoretical attenuation coefficients of 0.1229 and 0.1213 cm−1 for pure starch and 0.2202 cm−1 and 0.2178 cm−1 for the starch +50%WO3 biocomposite at 662 keV, respectively.

The radiation attenuation coefficients (RAC) of barite coated fabric for 137Cs and 60Co sources

Since its discovery, radiation becomes one of the most popular subjects for researcher. This is because of using radiation many different fields from medicine to agriculture. When using radiation it may be harmful for human cell and thus people should be protected. In this study, the photon attenuation coefficients of terry-cotton fabric have been measured and the effect of barite coating process is investigated. The measurements were performed using a Thallium-doped Sodium Iodide (NaI (Tl)) detector against 137Cs and 60Co sources (emit gamma rays of 662,1173 and1332 keV energies) and for fabric with coated barite rate of 0%, 40%, 50% and 60% (w%).

Calculation of X-ray attenuation coefficients for normal and cancerous breast tissues

The study was carried out by numerical integration based on the diffraction properties and elemental composition. The elemental compositions of breast tissues in the literature were tested. The photon attenuation coefficients calculated using the recent elemental composition were found within 0.2˗16% for adipose tissue and within 0.04˗17% for glandular tissue with the experimental reference data. The attenuation coefficients of cancerous breast tissue calculated according to the elemental content previously measured in breast cancer patients were found within 0˗17% with experimental data in the literature. The attenuation coefficients are of great interest to medical research. To calculate realistic attenuation coefficients, the characteristic coherent scatter, which is most intense at small angles, must be considered. For this reason, experimentally measured form factor data were reviewed, and the most compatible one with the theoretical form factor data produced in this study was used at low momentum transfer x (0 < x ≤ 8 nm−1). The differential linear coherent scattering distributions were calculated for an energy value of 17.44 keV and compared with their experimental counterparts.

Optical and radiation absorption properties of bismuth-borate glasses doped with Ce4 +, Nd3 +, and Sm3 +

Three bismuth-borate glasses with the chemical configuration 15Bi2O3-75 H3BO2-10CeO2, 15Bi2O3-75 H3BO2-10Nd2O3, and 15Bi2O3-75 H3BO2-10Sm2O3 and coded as BHB-Ce, BHB-Nd, and BHB-Nd were investigated for their optical and gamma-radiation absorption behaviour. Optical parameters of the glasses such as the molar refractivity, Rm, molar polarizability, αm, reflection loss RL, optical transmission T, metallization criterion M, static dielectric constant εstatic, and optical dielectric constant εoptical were calculated using standard theoretical models. The mass attenuation coefficient μ/ρof the glass samples was estimated by FLUKA simulations and XCOM for discrete photon beams with energies of 0.282, 0.662, 1.33, and 2.51 MeV. The value of Vm was 21.35, 22.61, and 19.60 cm3/mol for BHB-Ce, BHB-Nd, and BHB-Sm, respectively. Also, the highest Rm (16.52 cm3/mol) and αm (6.56 ×10−24 cm3) were obtained for BHB-Ce, while the lowest value was recorded for BHB-Nd (12.035 cm3/mol and 4.78 ×10−24 cm3). Other optical parameters varied with the dopant ion. The photon attenuation coefficient obtained from XCOM calculation and simulations agreed within a 2.90% margin. The μ/ρ varied within the interval 0.0422–0.3086 cm2/g for BHB-Ce, 0.0420–0.3005 cm2/g for BHB-Nd and 0.0420–0.3029 cm2/g for BHB-Sm. The half-value layers (HVLs) vary from 0.3948 cm to 2.8854 cm for BHB-Ce, from 0.3782 cm to 2.7063 cm for BHB-Nd and from 0.3223 cm to 2.3252 cm for BHB-Sm. Based on the values of the photon shielding parameters, the investigated glasses showed better ability to absorb photons compared to conventional shields such as barite concrete, ordinary concrete, and some commercial glass shields. The analysis of the optical and radiation absorption parameters shows that the BHB-glasses are useful in optical and gamma-radiation absorption technologies.

Surface hardness, thermal, optical, and photon attenuation coefficients assessment for dysprosium-doped tellurite glasses

Using a melt-cooling process with the host glass, Dy2O3 (1 wt%, 2 wt%, 3 wt%, and 4 wt%) doped tellurite glasses were produced. A (65–x)TeO2–20B2O3–10Al2O3–5GeO2–xDy2O3 glass system was analyzed by X-ray diffraction. The patterns have a hump at 2θ = 27°–29° and no sharp peaks, indicating that all the glass samples are amorphous. The Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder substance. Differential scanning calorimetry (DSC) at 300–550 °C was used to evaluate the thermal properties of the Dyx glass samples. The glass transition temperature Tg (small endothermic peak), start crystallization temperature Tx and crystallization temperature Tc can all be seen on the DSC thermogram (exothermic peaks). The UV–Vis transmittance and absorption spectra were measured. The optical data show that the values of Egdir, EgInd and EU decrease as the amount of Dy2O3 increases, indicating a narrowing of the tails due to localized states in the forbidden gap. A concentration quenching event occurs when Dy3+ concentrations are above a certain threshold (1%). The addition of Dy2O3 increases glass density, while the addition of other Dy(III) oxides increases sample density. The radiation shielding values change as a consequence of density fluctuation. The sample with the highest amount of Dy2O3 (Dy4) has stronger radiation shielding characteristics; hence, it is superior in terms of shielding outcomes at all energy levels. Such Dyx samples can be used in various forms of ionizing radiation shielding.

Quantification of the volume fraction of fat, water and bone mineral in spongiosa for red marrow dosimetry in molecular radiotherapy by using a dual-energy (SPECT/)CT

A patient-specific absorbed dose calculation for red marrow dosimetry requires quantifying patient-specific volume fractions of the red marrow, yellow marrow, and trabecular bone in the spongiosa of several skeletal sites. This quantification allows selecting appropriate S values calculated from the parameterized radiation transport models for bone and bone marrow dosimetry. Currently, no comprehensive, individualized, and non-invasive procedure is available for quantifying the volume fractions of red marrow, yellow marrow, and trabecular bone in the spongiosa. This study aims to provide a new quantitative method based on dual-energy computed tomography to fill this gap in red marrow dosimetry using a (SPECT/)CT system. MethodsFirst, a method for parametrizing the photon attenuation coefficients relative to water was implemented. Next, a method to calculate the effective atomic number (Zeff) and effective mass density (ρeff) using dual-energy CT (DECT) was employed. Lastly, two- and three-material decomposition using a dual-energy quantitative CT method (DEQCT) was performed in an anthropomorphic spine phantom and two bone samples of a boar, respectively.The measurements of Zeff and ρeff were compared with the syngo.CT DE Rho/Z tool (Siemens Healthineers). Furthermore, the DEQCT method implemented in this study (DEQCT-I) was compared with a second DEQCT method based on the use of external material standards (DEQCT-II). DEQCT-II was used as reference method for calculating relative errors. ResultsThe two-material decomposition in the anthropomorphic spine phantom presented a maximum relative error of −10% for the bone mineral density quantification. Furthermore, Zeff and ρeff calculated by DEQCT-I differed from syngo.CT DE Rho/Z tool by less than 4.4% and 1.9%, respectively. The three-material decomposition in the two bone samples showed a maximum relative error of 21%, −17%, and 15% for the quantification of the volume fractions of fat, water, and bone mineral equivalent materials. Lastly, Zeff and ρeff calculated by DEQCT-I differed from syngo.CT DE Rho/Z tool by less than 8.2% and 7.0%, respectively. ConclusionThis study shows that quantifying the volume fraction of fat, water, and bone mineral using a phantom-independent and post-reconstruction DEQCT method is feasible. DEQCT-I has the advantage of not requiring prior information about the X-ray spectra or the detector sensitivity function, as is the case with spectral-based DEQCT methods. Instead, DEQCT-I, similar to other DEQCT methods depends on the chemical description of reference materials and a beam hardening correction function.DEQCT-I method provides an individualized and non-invasive procedure using a (SPECT/)CT system to apply S values based on the patient-specific volume fractions of yellow marrow, red marrow, and bone mineral in red marrow dosimetry.

A comparative photon shielding properties of protective Window materials by using EGS5 code

For an X-ray room, there is a special window for radiation workers to monitor the patient during an irradiation procedure. Lead glass commonly used as protective window materials for diagnostic X-rays even it is known for its toxicity due to the lead oxide in the air which could be inhaled either during manufacturing or recycled process. Monte Carlo simulation (EGS5 code) was used to study several other types of available protective windows for its radiation shielding efficiency. In this study, the practicability of acrylic glass, plate glass and Pyrex glass systems with respect to lead glass were studied for protective window materials. The photon attenuation coefficients (μ), the percentage of transmitted and reflected photon energy spectra and half-value layer (HVL) were investigated by using simulation. Three photon source energies of 59.5 keV, 150 keV, and X-ray 150 kVp were calculated via EGS5 code to study the capability of these four glass systems as low energy photons radiation shielding materials. A thickness of 7 cm plate glass, 8 cm pyrex glass and more than 10 cm acrylic glass are adequate as a non-lead shielding material for 150 kVp X-ray to have a similar lead-glass equivalency. The use of plate glass as radiation protecting material to replace lead glass can reduce expenses as plate is way cheaper than lead but the increase thickness of plate will need special framing and concerns of its increased weight needs to be considered. However, given that the X-ray primary beam will not be directed towards the protective windows, therefore the findings are appropriate, with less thickness of plate glass could be used.

Calculation of the gamma radiation shielding efficiency of cement-bitumen portable container using MCNPX code

In the current study, the shielding characteristics of Portland cement combined with various percentages of bitumen (from 10% to 50%) materials were investigated. The MCNPX code was used to calculate the linear and mass attenuation coefficients, half and tenth value layers, and the mean free path for gamma rays. For the calculations, gamma sources (137Cs with 0.662 MeV and cobalt 60Co with an average energy of 1.25 MeV) were employed. In comparison to the cement paste solely, the cement-bitumen composites have a greater photon attenuation coefficient. It is suggested that new compositions can be used as shielding material for dual photon protection and would be recommended in casting containers of thickness 6 cm for embedding the cesium (137Cs) and cobalt (60Co) as a mobile container during transportation and long storage.

An analytical approach to organ equivalent dose estimation based on material composition photon attenuation coefficient

Monte Carlo photon transport calculation is widely used with anthropomorphic phantoms to estimate equivalent doses for different photon energies and exposure geometries. Although a high precision probabilistic method, it is computationally expensive. The uncertainties in the physical input parameters and deviations in the particle simulation from the actual exposure also limit the accuracy of the dose conversion coefficients. This study presents an analytical method of calculating the organ equivalent dose of virtual adults from external gamma radiation based on elemental tissue composition energy transfer, energy-absorption coefficient, and photon interaction. The two methods developed are based on ICRU-four and nine elements in tissues. The methods are subsequently used to estimate the equivalent dose for various organs in virtual male and female adults exposed to external monoenergetic gamma rays. The equivalent dose results from the simulated geometries show the accuracy and adaptability of the proposed method. The result is also in agreement with the International Commission on Radiological Protection (ICRP) publication 116. Moreover, the result shows that the proposed method can accurately calculate organ equivalent dose from external photon irradiation without considering the complex photon transport computations used in existing photon transport codes. In addition, compared with four other conventional approaches, the evaluation result shows that the proposed analytical approach enhances computation efficiency without compromising dose calculation accuracy.

Photon Attenuation Coefficients of Fly-Ash Based Geopolymers Synthesized with Different Barite Proportions

Mass attenuation coefficients of fly-ash based geopolymers fabricated with different proportions of barite are measured using a high-resolution NaI spectrometer detector. After fabrication, the samples were irradiated with gamma-rays emitted from point sources of 241Am and 137Cs. The measured experimental values are found to be consistent with theoretical calculations carried out using the XCOM program. Based on the results, the radiation shielding capacity of the geopolymers is found to increase with increase in barite proportion. In addition, the fly-ash based geopolymers fall within the internationally established range and are thus acceptable for use as radiation protection devices.

A new formulation of polymer gel dosimeter with reduced toxicity: Dosimetric characteristics and radiological properties

The present study aimed to produce a new, less toxic, and cost-effective polymer gel dosimeter using potassium salt of 2-acrylamido-2 methyl-propane sulfonic acid (AMPS) monomer. The new formulation was called PAKAG. The irradiation of PAKAG polymer gel dosimeter was performed using a 6 MV clinical linear accelerator, and its response was evaluated using magnetic resonance imaging. The obtained images were post-processed to produce related R2 maps. Afterward, the Dose–R2 calibration curves were obtained. Response dependence on the imaging temperature was examined. Furthermore, response stability over time was investigated. To investigate the radiological characteristics, the elemental composition, effective atomic number, electron density, and photon attenuation coefficient of PAKAG polymer gel dosimeter were calculated. A maximum sensitivity of 0.152±0.007 with the goodness of fit of R2=0.999 in a dynamic range of 0–6Gy at 12h post-irradiation time was found. Such as other polymer gel dosimeter, the response of PAKAG polymer gel dosimeter was dependent on post-irradiation time and imaging temperature. Finally, it was concluded that the PAKAG polymer gel dosimeter could be used as a less toxic and cost-effective polymer gel dosimeter.

X-ray and gamma ray shielding behavior of concrete blocks

The shielding characteristics of two concrete blocks, widely used in the building industry in Mexico have been determined. These characteristics include the mass interaction coefficients, the linear attenuation coefficients and the half-value layers. The energy-dispersed X-ray fluorescence shows that the percentage mass content of each atom in the sample, and the atomic volume of the constituent elements of a material, plays an important role in its shielding capabilities. The total linear attenuation coefficients and the half-value layers were analyzed for a set of photon energies related to X-rays for diagnosis and cancer treatment with linear accelerators. Our results show that the concrete blocks have similar photon attenuation coefficients than the Portland concrete and better features than gypsum.

Determination of Photon Attenuation Coefficients of Steel Doped Barite Plasters

The plaster is used as a flattening of the interior and exterior surfaces of the buildings and as decorative material. In this study, photon attenuation coefficients of barite plaster containing steel were measured. The measurements performed at 511, 835 and 1275 keV which are obtained from 22Na and 54Mn radioactive sources, using a gamma spectrometer that contains a NaI(Tl) detector and MCA. The measured results were compared with the calculation obtained using computer code of XCOM for 1 keV–1 GeV gamma energies. Also, half value layer (HVL) and tenth value layer (TVL) were calculated using the results obtained from the experimental measurement.

Feasibility of clay-shielding material for low-energy photons (Gamma/X)

Abstract While considering the photon attenuation coefficient (μ) and its related parameters for photons shielding, it is necessary to account for its transmitted and reflected photons energy spectra and dose contribution. Monte Carlo simulation was used to study the efficiency of clay (1.99 g cm−3) as a shielding material below 150 keV photon. Am-241 gamma source and an X-ray of 150 kVp were calculated. The calculated value of μ for Am-241 is higher within 5.61% compared to theoretical value for a single-energy photon. The calculated half-value layer (HVL) is 0.9335 cm, which is lower than that of ordinary concrete for X-ray of 150 kVp. A thickness of 2 cm clay was adequate to attenuate 90% and 85% of the incident photons from Am-241 and X-ray of 150 kVp, respectively. The same thickness of 2 cm could shield the gamma source dose rate of Am-241 (1 MBq) down to 0.0528 μSv/hr. For X-ray of 150 kVp, photons below 60 keV were significantly decreased with 2 cm clay and a dose rate reduction by ∼80%. The contribution of reflected photons and dose from the clay is negligible for both sources.

Photon attenuation coefficients of oxide dispersion strengthened steels by Geant4, XCOM and experimental data

The total mass attenuation coefficients (μ/ρ) of oxide dispersion strengthened (ODS) steels have been investigated by using Geant4 simulation toolkit at energies ranging from 0.01 MeV to 100 GeV. Moreover, Geant4 is applied to further study on the partial mass attenuation coefficient of three main interactions including photoelectric effect, compton scattering, gamma conversion between incident photon and ODS steels. Then molecular cross-section (σm) and mean free path (λ) are obtained by the total mass attenuation coefficients. The results obtained by Geant4 are compared with those obtained by experiments and XCOM program and these results agree with each other very well. It is concluded that Geant4 Monte Carlo toolkit is a powerful tool in studying interaction of photons in material and energies. The shielding parameters of ODS steels presented in this paper can be very useful for the potential nuclear application and other industries in future.

Radiation shielding properties of some ceramic wasted samples

The radiation has great importance in human life; it enters into various fields of agricultural, industrial, medical and food sterilization, for example, in the medical field, X-ray is used to diagnose many cases of a disease. The exposure to radiation has great risks to human life and must be protected against it. There are several ways to protect the human body from radiation; one of these ways is shielding; in the present work, eight types of ceramic materials have been used as a shielding material and tested against gamma ray, each type of ceramic modified as glazed and unglazed. The radiation sources 137Cs and 60Co were used to calculate attenuation coefficients and half-value layers by gamma-ray spectrometer system with scintillation detector NaI(Tl). The obtained results show that the photon attenuation coefficient for all samples decreases with increasing energy, while half-value layers increase with increasing energy. The results of the study showed that glazed ceramics are better than unglazed in the attenuation of gamma radiation which makes their use of shielding better.

Experimental implementation of a joint statistical image reconstruction method for proton stopping power mapping from dual-energy CT data.

To experimentally commission a dual-energy CT (DECT) joint statistical image reconstruction (JSIR) method, which is built on a linear basis vector model (BVM) of material characterization, for proton stopping power ratio (SPR) estimation. The JSIR-BVM method builds on the relationship between the energy-dependent photon attenuation coefficients and the proton stopping power via a pair of BVM component weights. The two BVM component images are simultaneously reconstructed from the acquired DECT sinograms and then used to predict the electron density and mean excitation energy (I-value), which are required by the Bethe equationfor SPR computation. A post-reconstruction image-based DECT method, which utilizes the two separate CT images reconstructed via the scanner's software, was implemented for comparison. The DECT measurement data were acquired on a Philips Brilliance scanner at 90 and 140kVp for two phantoms of different sizes. Each phantom contains 12 different soft and bony tissue surrogates with known compositions. The SPR estimation results were compared to the reference values computed from the known compositions. The difference of the computed water equivalent path lengths (WEPL) across the phantoms between the two methods was also compared. The overall root-mean-square (RMS) of SPR estimation error of the JSIR-BVM method are 0.33% and 0.37% for the head- and body-sized phantoms, respectively, and all SPR estimates of the test samples are within 0.7% of the reference ground truth. The image-based method achieves overall RMS errors of 2.35% and 2.50% for the head- and body-sized phantoms, respectively. The JSIR-BVM method also reduces the pixel-wise random variation by 4-fold to 6-fold within homogeneous regions compared to the image-based method. The average differences between the JSIR-BVM method and the image-based method are 0.54% and 1.02% for the head- and body-sized phantoms, respectively. By taking advantage of an accurate polychromatic CT data model and a model-based DECT statistical reconstruction algorithm, the JSIR-BVM method accounts for both systematic bias and random noise in the acquired DECT measurement data. Therefore, the JSIR-BVM method achieves good accuracy and precision on proton SPR estimation for various tissue surrogates and object sizes. In contrast, the experimentally achievable accuracy of the image-based method may be limited by the uncertainties in the image formation process. The result suggests that the JSIR-BVM method has the potential for more accurate SPR prediction compared to post-reconstruction image-based methods in clinical settings.

Application of neural network for predicting photon attenuation through materials

ABSTRACTPhoton attenuation prediction in composite materials usually requires a great expert knowledge and time-consuming calculations with complex procedures especially in experimental arrangements. An artificial neural network can be applied to predict exactly the value of mass attenuation at different energies. For training of the network a neural model was designed with chemical composition and molecular cross-section of samples as neural input, while the photon attenuation coefficient was its output. The method was applied for different composite materials with different chemical compositions. The results of mass attenuation coefficients were compared with the experimental and theoretical data for the same samples and a good agreement has been observed. The results indicate that this process can be followed to determine the data on the attenuation of gamma-rays with the several energies in different materials.

Borotellurite Glasses for Gamma-Ray Shielding: An Exploration of Photon Attenuation Coefficients and Structural and Thermal Properties

Gamma-ray attenuation characteristics and vibrational and thermal features have been studied for singly doped erbium (Er), dysprosium (Dy), and Er/Dy-codoped sodium lithium zinc lead borotellurite glasses. For all glasses, the amorphous nature was confirmed from the x-ray diffraction profiles, and BO3, BO4, TeO4, TeO3 +1, and TeO3 structural units were identified by both Fourier transform infrared spectroscopy and Raman spectroscopy. Glass transition (Tg), onset crystallization (Tx), peak crystallization (Tc), and melting (Tm) temperatures including thermal stabilities (ΔT) were evaluated following the glass differential scanning calorimetry profiles. An enhancement in Tg (359→399°C) and ΔT variation at 131–169°C with Er2O3, Dy2O3, and Er2O3/Dy2O3 incorporation suggested that the prepared glasses possess good thermal stability. The radiation shielding properties within the 0.356–1.33-MeV photon energy range were assessed for all the glasses. The mass attenuation coefficient (μ/ρ) values have been calculated using Monte Carlo simulation code. Further, photon interaction parameters like effective atomic number (Zeff), half-value layer (HVL), and mean free path (MFP) were also computed. The host and 1.0 Er/1.0 Dy (mol.%)-codoped glasses possess the lowest and highest Zeff values and their magnitudes are varied within the range 11.40–15.99 and 12.14–17.26, respectively. For the host glass, exposure buildup factor values were calculated by the geometric progression (GP) fitting method within the 0.015–15-MeV energy range and up to a penetration depth of 40 MFP. The removal cross sections ΣR (cm−1) for fast neutrons were calculated to evaluate the attenuation of neutrons through the prepared glasses.