Mass Energy Absorption Coefficients Research Articles

Statistical-based modeling strategy for entrance skin dose estimation in patient undergoing body interventional radiology.

Interventional radiology (IR) provides significant advancements in diagnostic and therapeutic procedures, yet concerns persist regarding radiological risks such as erythema, burns, and epilation. Direct dose measurements observed difficulties regarding the perturbation of the detector probe in X-ray images during fluoroscopy-guided procedures, high-cost expenses, and non-compliant patients. This study aims to develop a statistical-based model for estimating entrance skin dose (ESD) in body IR procedures using patient radiation-dose recording data. Models are categorized into vascular and non-vascular procedures. This study demonstrates that the simplified models are sufficient in estimating patient ESDs for both IR groups, with a 95% confidence interval. This user-friendly method enables radiologists to calculate doses without complex parameters such as the backscatter factor and mass-energy absorption coefficient, as required in conventional calculation methods. It not only does this support to radiologists in effectively refining treatment protocols, but also enables patients to monitor their received doses immediately after treatment ends.

Gamma Radiation Shielding and Interaction Properties of MoO3-Doped Cadmium Zinc Lithium-Borate Glasses

This study, theoretically examined the impact of MoO3 addition on gamma radiation shielding properties of cadmium zinc lithium-borate (BCZLMx) glasses to find the optimal quantity of molybdenum oxide (MoO3) needed for a stable glass matrix with excellent gamma shielding capabilities. Gamma radiation transmission parameters that include Mass attenuation coefficient, Mass energy absorption coefficient, Equivalent atomic number, Effective electron density, Dose rate, Exposure buildup factors and Energy absorption buildup factor were evaluated using FLUKA and XCOM computer programs. Results showed that 60B2O3-20CdO-10ZnO-8Li2O-2MoO3 (BCZLM5) was the most stable and efficient glass sample for X-rays and gamma radiation shielding across all photon energy ranges. Hence, BCZLM5 should be deployed for X-rays and gamma radiation shielding to provide maximum protection and exceptional safety for workers in hospital X-ray rooms and nuclear installations against ionizing radiation.

Gamma attenuation and radiation shielding performance of CaCu3B2Re2O12 (B[dbnd]Mn, Fe, Co, and Ni) perovskites

In order to identify the importance of perovskites in nuclear science, studies aimed at obtaining the radiation interaction quantities of perovskites are essential. This study computed and analyzed the gamma photon interaction parameters of CaCu3B2Re2O12 (BMn, Fe, Co, and Ni) perovskites to reveal their shielding potentials and comparative advantages against traditional shielding materials. Four samples of ferrimagnetic quaternary perovskites whose chemical structures are summarized as CaCu3B2Re2O12 (BMn (CCMRO1), Fe (CCMRO2), Co (CCMRO3), and Ni (CCMRO4)) were considered for their gamma interaction quantities. The values of mass attenuation coefficient (μρ) was calculated with XCOM and they were in the range of 0.0552 cm2/g–0.4162 cm2/g for CCMRO1, 0.0553 cm2/g–0.4165 cm2/g CCMRO2, 0.0552 cm2/g–0.4148 cm2/g for CCMRO3, and 0.0555 cm2/g–0.4163 cm2/g for CCMRO4. The values of effective atomic number and electron density was within the range 21.38–43.38 and 2.84 x 1023 electrons/g −5.62 x1023 electrons/g, respectively. The trend of the mass energy absorption coefficients of the perovskites was also found to be in the same order as the mass attenuation coefficient. CCMRO3 has the highest photon energy absorptive ability among the perovskites while CCMRO2 has the least capacity. Also, the gamma dose rates in15 mm thick of CCMRO1, CCMRO2, CCMRO3, and CCMRO4 for 1.25 MeV are about 1446 kR/h, 1449 kR/h, 1453 kR/h, and 1446 kR/h, respectively. Comparatively, the values of the exposure and energy absorption buildup factors were almost the same for the perovskites at the same energy and optical depth. The investigated perovskites had higher mass attenuation coefficients that standard shielding glasses. The perovskites can be used for shielding or any other radiation absorption roles in radiation science and technology, especially for photons at low energies.

Comparison of Monte Carlo tally techniques for dosimetry in a transmission-type x-ray tube.

This study discussed comparing result accuracy and time cost under different tally methods using MCNP6 for a novel transmission x-ray tube which was designed for the Auger electron yield with specific material (e.g. iodine). The assessment included photon spectrum, percent depth dose, mass-energy absorption coefficient corresponding to air and water, and figure of merit comparison. The mean energy of in-air phantom was from 41.8 keV (0 mm) to 40.9 keV (100 mm), and the mean energy of in-water phantom was from 41.41 keV (0 mm) to 45.2 keV (100 mm). The specific dose conversion factors based mass-energy absorption coefficient corresponding to different materials was established and the difference was less than 2% for the dose conversion of FMESH comparing to measurement data. FMESH had better figure of merit (FOM) than the F6 tally for the dose parameter assessment, which mean the dose calculation that focused on the superficial region could be assessed with more calculation efficiency by FMESH tally for this novel transmission x-ray tube. The results of this study could help develop treatment planning system (TPS) to quickly obtain the calculated data for phase space data establishment and heterogeneous correction under different physical condition settings.

Gamma attenuation and buildup factors of GeO2-Ga2O3–Gd2O3 transparent glass ceramics for shielding applications

While gamma radiation presents significant hazards, the development of reliable shielding materials is demanded. This research study aims to investigate the gamma attenuation and buildup factors of transparent glass ceramics with the composition described by the formula of 99 [60GeO2 + (40-y)Ga2O3 + yGd2O3] +1Nd2O3, with y = 13,15,17, and 19 mol%. The basic gamma attenuation factor, namely mass attenuation coefficient (MAC), is calculated theoretically by using WinXCOM. By using MAC values, obtained by WinXCOM, we estimated the other gamma attenuation factors such as effective atomic number (Zeff) and electron density (Neff). Moreover, the absorption parameters, such as mass energy-absorption coefficient (MEAC), and buildup factors are also evaluated. It is found that the highest Zeff values are observed at 0.015 MeV with the values of 37.648, 38.618, 39.577, and 40.528 for GN1, GN2, GN3, and GN4 respectively. Moreover, the Gd2O3 content has a significant effect to improve the attenuation capacity of the studied samples.

Simulation of the Effect of Dy3+ Dopant on the Mass Energy Absorption Coefficient and Relative Energy Response of TLD Made from Lithium Magnesium Borate Using MCNP

Thermoluminescence dosimeter (TLD) is widely used as a personal and medical dosimeter. Several TLD materials show the characteristics of mass energy absorption coefficient and energy response relative to ICRU (International Commission on Radiation Units and Measurements) issue material as an equivalent material for human body soft tissue. This research aims to analyze the effect of Dy3+ dopant on the mass-energy absorption coefficient and relative energy response of Lithium Magnesium Borate (LMB) materials. The simulation was carried out using Monte Carlo N-Particle (MCNP) software. Calculations based on simulation and theoretical results will be compared statistically using paired t-tests. The study showed that adding a Dy3+ dopant to TLD material made of Lithium Magnesium Borate (LMB) only affected the mass-energy absorption coefficient and relative energy response for low radiation energy. Adding Dy3+ dopant increased the mass energy absorption coefficient and relative energy response in a reasonably small value. Based on these results, LMBDy3+ produces a better mass-energy absorption coefficient value for TLD materials. The results of the statistical tests show a significant difference in the mass energy absorption coefficient value. At the same time, there is no significant difference between the simulation results and theoretical calculations for the relative energy response.

Evaluating the Kerma coefficients relevant to various water-equivalent materials at different photon energies

To investigate the water equivalency of some solid phantoms, relevant Kerma coefficients were determined through both Monte Carlo (MC) simulation and analytical approaches over a wide range of photon energies ranging from 1 keV to 20 MeV.MCNPX MC Code was employed to simulate the Kerma coefficients for A-150, PMMA, Polystyrene, Solid Water (RMI 457), Solid Phantom (RW3), Virtual water, Solid Water (WT1), and Water Equivalent (Wte) solid phantoms. Kerma coefficients were also theoretically calculated using the mass energy absorption coefficients at different photon energies ranging from 1 keV to 20 MeV. Obtained Kerma coefficients for considered solid phantoms were also compared with those of water to find which material shows the best water-equivalency.Calculated Kerma coefficients by MC simulation were in a good agreement with those calculated via an analytical method which no statistically significant differences were observed among simulated and analytically calculated Kerma coefficients (p-value>0.05). Solid water (RMI 457) showed the best water-equivalency among studied plastic phantoms for radiology and radiotherapy quality assurance purposes. From the results, the Kerma coefficients for solid phantoms are highly dependent on photon energy.

Analytical and fine Monte Carlo Kerma coefficients evaluation for a wide range photon energy relevant to some chemotherapy agents

Simultaneously combination of chemotherapy drugs and ionizing radiations has become a common treatment method for advanced cancers. Tumor irradiation in presence of chemotherapy drugs can affect deposited energy within tissue. Hence, to evaluate how chemotherapy drugs affect the absorbed dose within tissues during chemoradiotherapy, Kerma coefficient values for 26 anti-cancer agents were estimated for photon energies ranging from 1 keV to 20 MeV through analytical analysis and Monte Carlo (MC) simulation approaches.Estimation of Kerma coefficients through MC simulation relevant to different chemotherapy drugs was performed with MCNPX V.2.6.0 MC code. Besides, Kerma coefficient values were calculated using the reported mass energy absorption coefficients, as the theoretical method. Significant statistical test was also employed to evaluate the accordance of obtained Kerma coefficients by two considered methods.Simulation results were consistent with evaluated Kerma coefficients by analytical method which minimum and maximum mean relative differences are found for Bevacizumab and Methotrexate, respectively. Furthermore, a significant correlation is found with chemical composition of selected chemotherapy drugs at considered photon energy range. Fluorouracil showed the closest Kerma ratio to unity among the studied anti-cancer drugs. Kerma coefficient ratios for most of selected drugs were close to unity at higher energy regions (100 keV–20 MeV) while greater values were found at lower photon energies (below 100 keV).From the results, presence of these anti-cancer agents can impact Kerma coefficient and subsequently alter the absorbed dose within tissue during the cancer treatment with chemoradiotherapy technique.

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.