Mass Energy Absorption Coefficients Research Articles

Thermoplastic polymers as water substitutes

Background. New applications of 3D printing have recently appeared in the fields of radiotherapy and radiology, but the knowledge of many radiological characteristics of the compounds involved is still limited. Therefore, studies are needed to improve our understanding about the transport and interaction of ionizing radiation in these materials. Purpose. The purpose of this study is to perform an analysis of the most important radiation interaction parameters in thermoplastic materials used in Fused Deposition Modeling 3D printing. Additionally, we propose improvements to bring their characteristics closer to those of water and use them as water substitutes in applications such as radiodiagnosis, external radiotherapy, and brachytherapy. Methods. We have calculated different magnitudes as mass linear attenuation, mass energy absorption coefficients, as well as stopping power and electronic density of several thermoplastic materials along with various compounds that have been used as water substitutes and in a new proposed blend. To perform these computations, we have used the XCOM and ESTAR databases from NIST and the EGSnrc code for Montecarlo simulations. Results. From the representation of the calculated interaction parameters, we have been able to establish relationships between their properties and the proportion of certain chemical elements. In addition, studying these same characteristics in different commercial solutions used as substitutes for water phantoms allows us to extrapolate improvements for these polymers. Conclusion. The radiological characteristics of the analyzed thermoplastic materials can be improved by adding some chemical elements with atomic numbers higher than oxygen and by using polyethylene in new blends.

Radiation and nuclear shielding performance of tellurite glass system containing Li2O and MoO3: XCOM and FLUKA Monte Carlo

This study investigates the radiation attenuation properties of tellurite-based glasses with the chemical formula 75TeO2-(24-x)Li2O-(x)MoO3–1V2O5 (TLMV), where x = 0, 12, 24 mol%. The research focuses on important radiation protection values, such as the linear attenuation coefficient (μ), mass attenuation coefficient (μ/ρ), effective atomic number (Zeff), effective electron density (Neff), mass energy-absorption coefficient (MEAC), specific gamma-ray constants (Γ), gamma dose rate (Dr), mean free path (λ), half value layer (d1/2), and removal of fast neutrons (∑R). The gathered results indicate that changing Li2O and MoO3 mol% concentrations significantly impact shielding effectiveness. Additionally, this study compares the radiation shielding of TLMV glasses with commercial glasses, providing a comprehensive analysis for applications in healthcare, industrial, and related fields and exploring the potential usage of TLMV glasses in various shielding scenarios.

Gamma-ray, fast neutron and charged particle shielding performance of 15Li2O-25BaO-(40-x)B2O3-20P2O5-xDy2O3 glass system

Gamma-ray, fast neutron and charged particle shielding characteristics of Dy3＋ activated glasses with composition 15Li2O-25BaO-(40-x)B2O3-20P2O5-xDy2O3 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mol%) are analyzed in a wide incident energy for the first time. For gamma-ray shielding analysis, mass attenuation coefficient (MAC), mass energy absorption coefficient (μen), linear attenuation coefficient (LAC), mean free path (MFP), half-value layer (HVL), atomic cross-section (ACS), electronic cross-section (ECS), effective atomic number (Zeff), equivalent atomic number (Zeq), effective conductivity (Ceff), effective electron density (Neff), buildup factors (EABF and EBF), and kinetic energy released per unit mass of the absorbing material (KERMA) are calculated by using Phy-X/PSD and PAGEX softwares. For fast neutrons, fast neutron removal cross-section (FNRCS) is computed for all glass samples. For charged particle shielding analysis, mass stopping power (MSP), projected range (Rp), radiation yield (Ry), Zeff and Neff are computed using SRIM, ESTAR and PAGEX softwares. It is found that the glasses with increasing Dy3＋ have higher shielding potential. This suggests that the LBPDy1.0 sample has a potential use as shielding material for various applied fields.

Relativistic impulse approximation-based compton component of mass energy absorption coefficients (cm2/g) for few materials of medical interest

Total, whole-atom, individual and integrated Compton scattering cross sections and Compton energy absorption scattering cross sections are evaluated for light elements, such as, H, C, N, O, P, and Ca, with relativistic impulse approximation methods. Most of the phantom materials composed of these elements, which are the basic constituents of biological soft-tissue and attenuation through them, provides potential source of information. Compton scattering cross-sections for few biological materials, such as, H2O, C2H4, C8H8, C5H8O2, C6H11NO, C16H14O3, C55H102O6, [Ca3(PO4)]3Ca (OH)2 of medical interest, have been evaluated with the use of double differential scattering cross-section based on impulse approximation. Utilized these values to evaluate the Compton energy absorption cross sections and Compton component of mass energy absorption coefficients (cm2/g) in the energy region from 0.005 to 10 MeV. The derived results are compared with the theoretical tabulations.

Radiation attenuation of fly ash and rice husk ash-based geopolymers as cement replacement in concrete for shielding applications

Due to the economic and environmental cost of producing cement for concrete, research into the use of alternative materials such as geopolymers for the partial replacement of cement has become popular. In an attempt to understand the effect of such replacement on the shielding behavior of concrete, this study evaluated and analyzed the gamma-ray interaction parameters of fly ash- and rice husk ash-based geopolymers (G-RHA-F1, G-RHA-F2, G-RHA-F3, and G-RHA-F4). The mass attenuation coefficient (μρ), mass energy absorption coefficient (μenρ), effective atomic number (Zeff), specific gamma-ray dose constant (Г), dose rate (Dr), and photon buildup factors (BFs) were computed for photon energies within 15,000 eV and 15,000 keV. The evaluated parameters showed differences in value for the materials. For G-RHA-F1, G-RHA-F2, G-RHA-F3, and G-RHA-F4, μρ values are within the range 0.0208–6.5169 cm2/g, 0.0208–6.3631 cm2/g, 0.0209–6.70611 cm2/g, and 0.0208–6.2149 cm2/g, respectively. The corresponding ranges of are 0.0155–5.9433 cm2/g, 0.0155–5.7934 cm2/g, 0.0156–6.4016 cm2/g, and 0.0155–5.6775 cm2/g, accordingly. Fly ash slightly improved the gamma photon absorption capacity of the geopolymers, especially at the low energies. The investigated geopolymers have relatively higher photon absorption cross-sections relative to some existing polymers and shielding glasses. They could therefore be used to construct effective concrete shields.

An experimental work on radiation scattering features of some thermoluminescent dosimetry materials

In this study, albedo parameters are experimentally measured to determine radiation scattering features of some thermoluminescent dosimetry materials (TLD 100, TLD 100h, TLD 200 and TLD 400). In experimental setup, it was used scattering angle of 168°, 59.54 keV gamma rays and HPGe detector. The effective atomic numbers of the investigated materials were determined from the coherent to Compton scattering intensity ratio. Also, the mass attenuation coefficient, the mass energy absorption coefficient and kerma relative to air and ICRU tissue were calculated for the TLD materials. It was observed that TLD 100h is the best tissue equivalent material among other TLD materials and best reflects 59.54 keV gamma rays.

Physical, microstructural, and radiation energy absorption properties of recycled CRT-screen glass doped with Bi2O3

In this study, pristine TV-CRT screen glass (TVS) and those doped with 10% (TVS-Bi10) and 20% (TVS-Bi20) by weight of Bi2O3 were prepared and analyzed for their physical, microstructural, radiation dosimetry quantities, and shielding features. The glass samples were fabricated using the cold isostatic press method. The surface microstructure and the chemical composition of the glass ceramics were probed with the aid of the scanning electron microscopy-energy dispersive X-ray (SEM-EDX) system. Photon absorption and scattering quantities were estimated using standard procedures. The mean density values determined by Archimedes principle were calculated as 2.614, 2.788, and 3.056 gr/cm3 for the TVS, TVS-Bi10, and TVS-Bi20 samples, respectively. SEM images of samples showed that the increase in bismuth content increased sample crystallization and surface pores. The estimated mass energy absorption coefficients of the samples varied from 0.0177 to 11.7578 cm2/g for TVS, 0.0182–14.5218 cm2/g for TVS-Bi10, and 0.0187–17.7615 cm2/g for TVS-Bi20 for photon energies between 15 keV and 15 MeV. At 1 mm glass thickness and for 100 keV gamma rays, the dose rate was 13 MR/h, 17 MR/h, and 22 MR/h for TVS, TVS-Bi10, and TVS-Bi20, respectively. The mass stopping powers of electrons at 15 keV have values of 12.37 MeV cm2/g 12.21 MeV cm2/g, and 12.03 MeV cm2/g for TVS, TVS-Bi10, and TVS-Bi20, respectively. Generally, the ranges of the CPs were such that those of TVS > TVS-Bi10>TVS-Bi20. Bi2O3 increases the electron, proton, alpha particle, and carbon ion absorbing features of the TVS-BiX samples. Bi2O3 suppresses photon scattering, makes the TVS glass more sensitive to photon and charged particle interaction and absorption. The investigated glasses are useful for gamma-radiation, light, and heavy ion absorption and protection technology.

A Method for <i>In Vivo</i> Dosimetry Using an Electronic Portal Imaging Device

The implementation of advanced radiotherapy techniques such as Intensity-Modulated RadiationTherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) allows much more accuratecontrol of the irradiation area and more conformal dose delivery. Since these treatments are characterizedby high dose gradients and hence small error margins, they also require advanced and highlyeffective treatment verification techniques. Fortunately, an imaging modality, originally intended forset-up verifications, called the Electronic Portal Imaging Device (EPID) was reported to have hugepotential for dosimetry and treatment verification applications. However, methods and algorithmspreviously developed for EPID dosimetry are not yet widely adopted in cancer centers due to complexitiesin the implementation. These motivate more investigation and development of new methodsto encourage cancer centers to practice EPID dosimetry and improve patient safety.This research generally aims to develop an in-vivo dosimetry method that can be used in the future toapproximate the actual dose delivered inside the target by utilizing the transmitted fluence detectedby the EPID. In this study, Monte Carlo simulations are carried out using the Geant4 Application forTomographic Emission (GATE) to implement a virtual set-up composed of a water target irradiatedwith a monoenergetic 2 MeV photon beam and an EPID model to detect the total transmitted fluence.A mathematical model has been proposed to calculate the target absorbed dose by utilizing the transmittedprimary fluence. This involves back-projection of the transmitted fluence to determine fluencevalues at certain depths inside the irradiated homogeneous medium. This is followed by the calculationof the collision kerma using the back-projected fluence and the values of the linear attenuation coefficientand mass energy absorption coefficient in the National Institute of Standards and Technology(NIST) database. The results show accurate prediction of the fluence values inside the target, calculationof the corresponding values of the collision kerma, and determination of the proportionalityconstant β that relates the collision kerma to the target absorbed dose.

Investigating the suitability of newly developed epoxy-based equivalent tissues for newborn and 5-year-old in paediatric radiology

The varied radiological applications of tissue equivalent (TE) materials encompass quality checks, diagnostic imaging, and dose evaluations. However, the availability of compounds representing paediatric patient tissues for scientific use in lower diagnostic photon energy spectra is limited. In this study, several TE substitutes were developed to replicate the radiographic characteristics of neonatal soft tissue (ESST-NB), neonatal skeletal tissue (ESTB-NB), and equivalent tissues of a 5-year-old child (ESST and ESBT, respectively) within these energy ranges. The ORNL stylized computational model series was utilised as the primary reference for obtaining the desired elemental ratios. The density, effective atomic number, CT numbers, and electron densities obtained for the developed tissue substitutes exhibited a close resemblance to those of the reference phantom system, demonstrating a high level of accuracy and agreement. Furthermore, in order to accommodate constraints related to material selection and production, significant correlations were established between the obtained data and the reference values for mass densities, mass attenuation coefficients, and mass energy-absorption coefficients. In comparison to the ORNL reference samples, the neonates TE substitutions showed maximum discrepancies μ/ρ ranging from +1.6% to −3.01% and μen/ρ from +1.15% to −1.4% throughout an energy range from 47 keV to 66 keV. For the TE materials representing a 5-year-old, the corresponding comparable data ranges were +1.09% to −3.02% and +1.92% to −2.53%. These tissues may then be utilised to produce physical phantoms for neonates and 5-year-old as a result of the great concordance established between the newly built TE materials and the reference data.

Study of Effective Atomic Number, Mass Energy Absorption Coefficient and Absorbed Dose Rate in Human Organ and Tissue Substitutes

Abstract: The effective atomic number and mass energy absorption coefficient are two essential parameters used to investigate the radiation response of composite materials of dosimetric interest in many medical applications. The effective atomic number of nine selected human tissues and eleven samples of tissue substitute materials were computed using two methods, the interpolation method and the direct method in the energy range used in brachytherapy applications (0.1-2.0) MeV. The applicability of using the effective atomic number values to investigate scatter and absorption properties of some tissue substitutes, against that of the corresponding human tissues, to validate their tissue-equivalency, is examined. The effect of partial interaction cross sections is also explicitly discussed. Further, the absorbed dose rate, for an isotropic point source, in the selected tissue samples was computed using their estimated mass energy absorption coefficient values. The obtained data are analyzed and differences in sample dose rate relative to water, for photon energies of interest, are evaluated. The results indicate that numbers of tissue substitute samples yield estimates of dose rate to within 5% of dose rate of their corresponding human tissues. The obtained results are expected to be useful in improving dose calculation accuracy in brachytherapy treatment planning or dose evaluation after treatment. Keywords: Dosimetry, Human organs and tissues, Tissue equivalent materials, Equivalent atomic number, Attenuation and absorption coefficients.

Dose estimation in X-ray backscatter imaging with Timepix3 and TLD detectors

Nowadays, the detection of backscatter X-rays has become an essential part of road security scanners, where individuals are at risk of an accidental exposure to the pulsed photon radiation fields generated by the devices that implement this technique. Dose to soft-tissue measurements of a pulsed radiation field generated by a commercial cargo X-ray backscattering device are presented using a Timepix3 detector. To accurately estimate the imparted dose, the energy spectrum of a backscattering cargo scanner is measured with a thick CdZnTe hybrid semiconductor pixel detector. The deconvolution of this measured spectrum is performed and the contributions to the dose are calculated by means of the mass energy-absorption coefficients for soft-tissue. This methodology was assessed through a Monte-Carlo simulation, together with verification measurements using thermoluminescent detectors (TLDs) as a standard dosimetry system. Measurements of direct irradiation, for a 30 s scan with the device at 2 m from the detector, yielded a dose of (4.9 ± 0.7) μGy and (3.6 ± 0.3) μGy for the Timepix3 and TLDs, respectively. In a simulated cargo environment, with the detector behind a 1 mm thick steel wall, 30 s scan time, and 2 m source to detector distance, the dose measured by the Timepix3 was (1.7 ± 0.1) μGy, while for the TLDs (1.4 ± 0.6) μGy, showing that the proposed methodology has a similar response as compared to a standard dosimetry system.

Comparison of the dosimetric response of two Sr salts irradiated with 60Co γ-rays and synchrotron X-rays at ultra-high dose rate

As part of the development of innovative radiotherapy techniques using X-ray synchrotron sources, namely FLASH-radiotherapy and microbeam radiation therapy (MRT), two rod dosimeters based on strontium sulfate (SrSO4) and strontium carbonate (SrCO3) were developed and irradiated at the ESRF-ID17 Biomedical beamline to investigate new solid-state dosimeters.The radiation-induced defect in Sr-based dosimeters was detected by means of an electron paramagnetic resonance (EPR) spectrometer. For the study, the EPR response of the dosimeters irradiated with synchrotron X-rays in the 30–600 keV range and dose rate of 11.6 kGy/s was compared with the response after irradiation with a 60Co γ-ray source with a dose rate of 0.288 Gy/s.Both Sr dosimeters show an increased intensity of the EPR signal in the case of irradiation at the synchrotron with respect to the case of 60Co γ-ray irradiation. The measured enhancement of the delivered dose is explained by the fact that Sr shows an increased photoelectric interaction at orthovoltage X-ray energies, producing an increased number of free radicals.The experimental relative response rESRF of the EPR signals between samples irradiated at the ID17 beamline and the 60Co beam quality was found to be 9.66 for SrSO4 and 11.19 for SrCO3. Meanwhile, the theoritical relative responses rμen/ρESRF calculated as the ratio of mass energy absorption coefficients (μen/ρ) of the dosimeters to that for water at the ID17 with respect to the 60Co beam was found to be 11.85 for SrSO4 and 13.31 for SrCO3.The increased EPR response of Sr salt dosimeters irradiated with photons in the keV range proved that these detectors type could be a good candidate for the development of very sensible detectors for radiotherapy applications.

Investigation of the nuclear radiation interaction parameters of selected polymers for radiation therapy and dosimetry.

The mass attenuation coefficient (MAC), effective atomic number (Zeff), equivalent atomic number (Zeq), fast neutron removal cross-section (FNRCS), energy absorption buildup factor (EABF), mass-energy absorption coefficient (MenAC), relative kerma, and computed tomography (CT) numbers were calculated for the alginates, bisphenol A-glycidyl methacrylate (Bis-GMA), chitin, hyaluronic acid, polycaprolactone (PCL), polyether ether ketone (PEEK), polyethylene glycol (PEG), polyglycolide (PGA), polylactic acid (PLA), poly lacto-co-glycolic acid (PLGA), poly methyl methacrylate (PMMA), poly vinyl alcohol (PVA), polyvinylpyrrolidone (PVP), triethylene glycol dimethacrylate (TEGDMA), and urethane dimethacrylate (UDMA) polymers using the Phy-X/PSD and Py-MLBUF software. The total stopping power (TSP) of electrons, protons, and alpha particles was calculated for the selected polymers using the ESTAR, PSTAR, and ASTAR programs. The effective atomic number for absorption and charged particle (electron, proton, alpha, and carbon ion) interactions were estimated for the selected polymers using Phy-X/ZeXTRa software. The FNRCS values of Bis-GMA, PCL, PEG, PMMA, and PVP were similar to those of the human tissues. For the selected polymers, the Zeff values for electron, proton, alpha, and carbon ion interactions of PCL, PEG, PLGA, and PVA were similar to those of human tissues, except for the cortical bone, across the entire energy range. These results are expected to assist in selecting suitable polymers as tissue-equivalent materials in the desired energy range for photon, neutron, and charged-particle interactions. This study is expected to be useful for radiation therapy and dosimetry.

Clinical treatment planning for kilovoltage radiotherapy using EGSnrc and Python.

Kilovoltage radiotherapy dose calculations are generally performed with manual point dose calculations based on water dosimetry. Tissue heterogeneities, irregular surfaces, and introduction of lead cutouts for treatment are either not taken into account or crudely approximated in manual calculations. Full Monte Carlo (MC) simulations can account for these limitations but require a validated treatment unit model, accurately segmented patient tissues and a treatment planning interface (TPI) to facilitate the simulation setup and result analysis. EGSnrc was used in this work to create a model of Xstrahl kilovoltage unit extending the range of energies, applicators, and validation parameters previously published. The novel functionality of the Python-based framework developed in this work allowed beam modification using custom lead cutouts and shields, commonly present in kilovoltage treatments, as well as absolute dose normalization using the output of the unit. 3D user-friendly planning interface of the developed framework facilitated non-co-planar beam setups for CT phantom MC simulations in DOSXYZnrc. The MC models of 49 clinical beams showed good agreement with measured and reference data, to within 2% for percentage depth dose curves, 4% for beam profiles at various depths, 2% for backscatter factors, 0.5 mm of absorber material for half-value layers, and 3% for outputfactors. End-to-end testing of the framework using custom lead cutouts resulted in good agreement to within 3% of absolute dose distribution between simulations and EBT3 GafChromic film measurements. Gamma analysis demonstrated poor agreement at the field edges which was attributed to the limitations of simulating smooth cutout shapes. Dose simulated in a heterogeneous phantom agreed to within 7% with measured values converted using the ratio of mass energy absorption coefficients of appropriate tissues andair.

Influence of BaO/ZnCl2 content on gamma transmission properties of the optical TeO2-based glass system

Tellurite glasses possess attributes that make them attractive for potential radiation shielding uses. are Gamma radiation shielding quantities for three 70TeO2–(30-x)BaO–xZnCl2 glass samples (x = 5 (TBZC-A, 15 (TBZC-B), and 25 (TBZC-C) mol.%) were estimated and presented in this report. The mass attenuation coefficient MAC and buildup factors were estimated theoretically using XCOM and geometric progression fitting methods respectively for photon energies 15 keV ≤ E ≤ 15 MeV. The MAC vary within the limits 0.03374 − 45.20520 cm2/g for TBZC-A, 0.03321–44.30207 cm2/g for TBZC-B and 0.03267–43.37889 cm2/g for TBZC-C. Also, the mass energy absorption coefficients of the glasses ranged from 0.02021 to 42.32862, 0.02021–40.83892 0.02020–39.31615 cm2/g for TBZC-A, TBZC-B, and TBZC-C respectively. The effective atomic number of the glasses fluctuates within 25.01–52.03, 24.06–50.70 and 23.17–49.09 for TBZC-A, TBZC-B and TBZC-C, respectively. Analysis of sundry shielding and dosimetric parameters indicated higher photon intensity and energy absorption in BaO rich glasses compared to ZnCl2 rich glasses. The present glasses are relatively better than some existing glass shields thus making them potentially useful in gamma radiation absorption roles in gamma radiation based systems/facilities.

PHANTOM EXPERIMENTAL STUDY ON PATIENT DOSES OBTAINED FROM 320-MULTIDETECTOR-ROW COMPUTED TOMOGRAPHY IN WHOLE-BRAIN PERFUSION SCAN.

This study aimed to precisely evaluate organ dose and effective dose (E) obtained from a 320-multidetector-row computed tomography (CT) scanner in brain perfusion scans and to estimate the conversion factor (k) between E and dose length product (DLP). A total of 270 thermoluminescent dosemeters were implanted in a male anthropomorphic phantom to measure air kerma. The ratios of mass-energy absorption coefficients were used to convert air kerma into organ doses. The organ doses ranged from 0.01 to 150mGy. Doses in brain, salivary glands and red bone marrow were relatively high, and dose in eye lens reached about 110mGy. The resulting effective dose was 5.30mSv. The resulting conversion factor k=(0.0022±0.0002) mSv·(mGy·cm)-1 was not significantly different from that of 0.0021mSv·(mGy·cm)-1 reported for head CT scan in ICRP Publication 102.

Gamma shielding performance of the optical B2O3-based glass system

The gamma shielding and dosimetric quantities of the optical (55-x)B2O3 − 20CaF2- 5GeO2- 20Bi2O3-xCuO glass system are reported here. We studied different concentrations of CuO content, that is, 0 (BCGBC1), 1 (BCGBC2), 3 (BCGBC3), and 5 (BCGBC4) mol%. The mass attenuation coefficient of the glass system was estimated for 15 – 15,000 keV photons through the use of XCOM. Other photon shielding and dosimetric quantities such as mass energy absorption coefficient μen, specific gamma ray constant Γ, equivalent atomic number Zeq, effective atomic number Zeff, effective electron density Neff, gamma dose rate Dr and gamma photon buildup factors (exposure (EBF) and energy absorption (EABF) are estimated using standard deterministic expressions. Analysis of other related photon absorption quantities shows that there is a thin line between the gamma shielding ability of the glasses especially at energies beyond 0.1 MeV. In addition, the increase in the CuO content of the glasses slightly decreased the photon buildup within the glasses. The potential of the glasses to function well in radiation protective relation applications was demonstrated by the higher mass attenuation coefficient of BCGBC4 glass compared to different commercial shielding glasses, concrete samples, and other categories of materials with high shielding functionality.

Optical properties and photon-shielding performance of B2O3-based glasses

TThis work reports experimental and theoretical studies of the optical and photon shielding factors of a borate glass system with the chemical structure: TiO2:3CaO:Al2O3:15Na2O (80−x)B2O3:xZnO (x = 0, 5, 10 and 15 wt.%). The molar refractivity , molar polarization αMol, reflectance loss, optical transmission, metallization criterion, and static dielectric constant were calculated via UV spectroscopy based on the standard formula while the mass attenuation coefficient (MAC) and mass energy absorption coefficient (MEAC) were obtained from XCOM for gamma ray energies 0.015 -15 MeV. All estimated parameters showed dependence on the chemical stoichiometry of the glasses. The Rm and αMol of the glasses decreased from 15.34 – 13.51 cm3/mol and 6.23 – 5.41 x10-24 cm3 respectively. The MAC fluctuated within the values of 0.01819-2.65347 cm2/g, 0.01884-5.86148 cm2/g, 0.01949-9.06948 cm2/g and 0.02013-12.27748 cm2/g while the MEAC varied between 0.01364-2.77151 cm2/g, 0.01408-5.17928 cm2/g, 0.01451-7.58705 cm2/g and 0.01495-9.99482 cm2/g for ZnO concentration of 0 – 15 wt% respectively. The present glass system showed good radiation shielding potential for transparent photon absorption functions especially at low photon energies.

Fabrication and characterization of La2O3–Fe2O3–Bi2O3 nanopowders: Effects of La2O3 addition on structure, optical, and radiation-absorption properties

In this study, we fabricated and characterized six new nanopowders representing variations of La2O3–Fe2O3–Bi2O3, i.e., 100Bi2O3, 30Fe2O3–70Bi2O3, 3La2O3–27Fe2O3–70Bi2O3, 7La2O3–23Fe2O3–70Bi2O3, 10La2O3–20Fe2O3–70Bi2O3, and 20La2O3–10Fe2O3–70Bi2O3 (represented by 100B, 30F70B, 3L27F70B, 10L20F70B, and 20L10F70B, respectively). These nanopowders were prepared by the microwave-assisted hydrothermal synthesis method. Saponin extract from soapnuts was used as the nanoparticle capping agent. The structural, optical, and gamma radiation characteristics were measured, calculated, and analysed, respectively. The chemical structures of the nanocomposites influenced their optical and radiation shielding characteristics. The optical bandgaps of the 100B, 30F70B, 3L27F70B, 7L23F70B, 10L20F70B, and 20L10F70B nanopowders were 3.16, 3.13, 3.43, 3.45, 3.46, and 3.58 eV, respectively. The ranges of the mass attenuation coefficients of the nanopowders were computed, using XCOM, to be 0.0412–5.1624, 0.0401–4.5406, 0.0401–4.5285, 0.0401–4.5129, 0.0401–0.5015, and 0.0400–4.4156 cm2/g, respectively, and the ranges of mass energy absorption coefficients were found to be 0.0232–1.7525, 0.0228–1.5484, 0.0228–1.5598, 0.0288–1.5746, 0.0228–1.5853, and 0.0227–1.6192 cm2/g, respectively, for photon energies in the range of 0.1–10 MeV. The order of the dose rate trend was as follows: 30F70B < L27F70B < 7L23F70B < 10L20F70B < 20L10F70B. Analysis of the photon interaction parameters showed that the synthesized nanopowders could function well as fillers in radiation-shielding matrices.

Buildup Factor Computation and Percentage Depth Dose Simulation of Tissue Mimicking Materials for an External Photon Beam (0.15–15 MeV)

Nowadays, the use of tissue mimicking material (TMM) is widespread in both diagnostic and therapeutic medicine, as well as for quality assurance and control. For example, patient exposure evaluation during therapeutic tests has been commonly measured using TMMs. However, only a few materials have been developed for research use at the megavoltage photon energy encountered in medical radiology. In this paper, we extended our previous work to cover the photon energy range of 0.15–15 MeV for five human tissues (adipose, cortical bone, fat, lung and muscle). As a selection criterion for TMM, other than the attenuation coefficient, we introduced the computation of the buildup factor (BUF) for a given couple of energy and depth based on the geometric progression fitting method. Hence, we developed a C++ program able to compute BUF for depths up to 40 mean free path. Moreover, we simulated the percentage depth dose (PDD) of a 6 MV photon beam through each tissue and their equivalent materials using the Geant4 Monte Carlo toolkit (version 10.5). After the comparison of a set of parameters (mass attenuation and mass energy absorption coefficients, BUF, equivalent and effective atomic numbers, electron density, superficial and maximal dose and dose at 10 and 20 cm depths), we found that SB3 (a mixture of epoxy and calcium carbonate) and MS15 (a mixture of epoxy, phenol, polyethylene and aluminum oxide) accurately imitate cortical bone and muscle tissues, respectively. AP6 (a mixture of epoxy, phenol, polyethylene and teflon), glycerol trioleate and LN1 (a mixture of polyurethane and aluminum oxide) are also suitable TMMs for adipose, fat and lung tissues, respectively. Therefore, this work can be useful to physician researchers in dosimetry and radiological diagnosis.