X-ray Radiation Dose Research Articles

Delayed effects of a single-dose whole-brain radiation therapy on glucose metabolism and myelin density: a longitudinal PET study

Purpose Radiotherapy is an important treatment option for brain tumors, but the unavoidable irradiation of normal brain tissue can lead to delayed cognitive impairment. The mechanisms involved are still not well explained and, therefore, new tools to investigate the processes leading to the delayed symptoms of brain irradiation are warranted. In this study, positron emission tomography (PET) is used to explore delayed functional changes induced by brain irradiation. Materials and methods Male Wistar rats were subjected to a single 25-Gy dose of whole brain X-ray irradiation, or sham-irradiation. To investigate delayed effects of radiation on cerebral glucose metabolism and myelin density, 18F-fluorodeoxyglucose (18F-FDG) PET scans were performed at baseline and on day 64 and 94, whereas N-11C-methyl-4,4′-diaminostilbene (11C-MeDAS) PET scans were performed at baseline and on day 60 and 90 post-irradiation. In addition, the open field test (OFT) and novel spatial recognition (NSR) test were performed at baseline and on days 59 and 89 to investigate whether whole brain irradiation induces behavioral changes. Results Whole-brain irradiation caused loss of bodyweight and delayed cerebral hypometabolism, with 18F-FDG uptake in all brain regions being significantly decreased in irradiated rat on day 64 while it remained unchanged in control animals. Only amygdala and cortical brain regions of irradiated rats still showed reduced 18F-FDG uptake on day 94. 11C-MeDAS uptake in control animals was significantly lower on days 60 and 90 than at the baseline, suggesting a reduction in myelin density in young adults. In irradiated animals, 11C-MeDAS uptake was similarly reduced on day 60, but on day 90 tracer uptake was somewhat increased and not significantly different from baseline anymore. Behavioral tests showed a similar pattern in control and irradiated animals. In both groups, the OFT showed significantly reduced mobility on days 59 and 89, whereas the NSR did not reveal any significant changes in spatial memory over time. Interestingly, a positive correlation between the NSR and 11C-MeDAS uptake was observed in irradiated rats. Conclusions Whole-brain irradiation causes delayed brain hypometabolism, which is not accompanied by white matter loss. Irradiated animals showed similar behavioral changes over time as control animals and, therefore, cerebral hypometabolism could not be linked to behavioral abnormalities. However, spatial memory seems to be associated with myelin density in irradiated rats.

Microbicidal effectiveness of irradiation from Gamma and X-ray sources at different dose rates against the foodborne illness pathogens Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes in rice

The radiation response of three foodborne illness pathogens was examined for irradiation with cobalt-60 Gamma and low-energy (125 keV) X-ray at different dose rates. Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes were inoculated into rice and irradiated at target doses of 0 (control), 250, 500, 750, 1000, and 1500 Gy with either Gamma radiation (dose rates of 9.1, 3.9 or 0.22 kGy/h) or X-ray radiation (dose rate of 0.76 kGy/h). Doses were measured with traceability to national standards. The dose rate did not significantly affect D10 values (microbicidal effectiveness) for any of the Gamma-irradiated pathogens. Low energy X-ray irradiated pathogens had significantly higher D10 values (lower microbicidal effectiveness) for all pathogens compared to Gamma-irradiated pathogens. The combination of Gamma or X-ray irradiation with a mixture of oregano/thyme essential oil (EO) fumigation generally increased the microbicidal effectiveness compared to irradiation alone. Gamma or low energy X-ray irradiation and plant essential oils such as oregano/thyme, applied alone or in combination, are effective antimicrobial treatments.

Treatment of keloids with a single dose of low-energy superficial X-ray radiation to prevent recurrence after surgical excision: An in vitro and in vivo study

Although keloids have been empirically treated with steroids and radiation, evidence-based radiation parameters for keloid therapy are lacking. To determine evidence-based radiation parameters for blocking keloid fibroblast proliferation invitro and apply them to patients. The effects of various radiation parameters and steroids on cell proliferation, cell death, and collagen production in keloid explants and fibroblasts were evaluated with standard assays. Effective radiation parameters were then tested on patients. No differences were observed between the effects of 50 and 320 kV radiation or between single and fractionated radiation doses on keloid fibroblasts. A 3 Gy, 50 kV dose inhibited keloid fibroblast proliferation in culture, whereas 9Gy completely blocked their outgrowth from explants by inducing multiple cell death pathways and reducing collagen levels. Thirteen of 14 keloids treated with a single 8 Gy, 50 kV dose of radiation did not recur, although 4 patients with 6 keloids were lost to follow-up. Seventy-five percent of patients received steroids for pruritus, whereas approximately 25% of patients were lost to follow-up. A single 8 Gy dose of superficial 50 kV radiation delivered an average of 34days after keloid excision maybe sufficient to minimize recurrence, including in individuals resistant to steroids. Higher radiation energies, doses, or fractions may be unnecessary for keloid therapy.

Unloading-Induced Cortical Bone Loss is Exacerbated by Low-Dose Irradiation During a Simulated Deep Space Exploration Mission.

Spaceflight-induced bone losses have been reliably reproduced in Hind-Limb-Unloading (HLU) rodent models. However, a considerable knowledge gap exists regarding the effects of low-dose radiation and microgravity together. Ten-week-old male C57BL/6J mice, randomly allocated to Control (CONT), Hind-Limb Unloading (HLU), and Hind-Limb Unloading plus Irradiation (HLUIR), were acclimatized at 28°C, close to thermoneutral temperature, for 28 days prior to the 14-day HLU protocol. HLUIR mice received a 25mGy dose of X-ray irradiation, simulating 14days of exposure to the deep space radiation environment, on day 7 of the HLU protocol. Trabecular bone mass was similarly reduced in HLU and HLUIR mice when compared to CONT, with losses driven by osteoclastic bone resorption rather than changes to osteoblastic bone formation. Femoral cortical thickness was reduced only in the HLUIR mice (102μm, 97.5-107) as compared to CONT (108.5μm, 102.5-120.5). Bone surface area was also reduced only in the HLUIR group, with no difference between HLU and CONT. Cortical losses were driven by osteoclastic resorption on the posterior endosteal surface of the distal femoral diaphysis, with no increase in the numbers of dead osteocytes. In conclusion, we show that low-dose radiation exposure negatively influences bone physiology beyond that induced by microgravity alone.

Evaluation of the Effects of Curcumin and Lycopene Treatment on Human Lymphocytes before 2 and 6 Gy of 6 MV X-Ray Irradiation

Introduction: Today, the use of ionizing radiation in medicine has grown as an important tool for diagnosis and treatment of diseases. However, the harmful effects of radiation should be also considered. Some substances such as lycopene and curcumin can reduce or increase the harmful effects of radiation on humans. So the aim of this study was to evaluate the radioprotective effects of lycopene and curcumin based on the MN assay. Material and Methods: In this study, the effects of lycopene and curcumin on reducing or increasing the harmful effects of radiation were studied using the micronucleus assay. The effects of lycopene (5 μg/mL) and curcumin (5 μg/mL) were evaluated at radiation doses of 2 and 6 Gy. Results: The results indicated that the simultaneous use of curcumin and lycopene can be radioprotective at low radiation doses (2 Gy; p 0.05). Conclusion: Based on the present results, further research using other methods may contribute to our understanding of the effect of simultaneous use of curcumin and lycopene at low and high doses of X-ray radiation.

The performance of chitosan layer in Au/n-Si sandwich structures as a barrier modifier

This study focused on the structural, optical and electrical features of chitosan organic layer obtained by spin coating technique both on glass and n-Si substrates. XRD results indicated that chitosan has polycrystalline orthorhombic nature. While optical transmittance spectrum of the chitosan organic layer exhibited an increasing tendency in the visible range, band gap energy value was calculated as 4.23 eV for chitosan by UV–Vis spectrometer. Electrical performance of organic chitosan layer in a Schottky device was studied by fabricating of Au/n-Si and Au/chitosan/n-Si devices. The suitability of Au/chitosan/n-Si sandwich devices in optoelectronic applications were tested under dark and illumination conditions. The Au/chitosan/n-Si sandwich device exhibits good photodiode characteristics. Furthermore, the effect of X-ray radiation doses on the electrical properties of the Au/chitosan/n-Si sandwich device was also investigated. In order to get information about electrical characteristics as a function of X-ray radiation doses, Au/chitosan/n-Si sandwich device was exposed to X-ray radiation in same exposure time and various doses. The results highlighted that the performance of the device with chitosan organic interface layer deteriorated with increasing radiation dose. In addition, the transportation mechanism of chitosan based Schottky device was discussed in details.

Novel 3D polymer gel dosimeters based on N-(3-Methoxypropyl)acrylamide (NMPAGAT) for quality assurance in radiation oncology

New anoxic and normoxic polymer gel dosimeters containing different concentrations of N-(3-Methoxypropyl) acrylamide (NMPA) are introduced in this investigation for radiotherapy treatment planning dose validation. NMPA dosimeters were irradiated to 20 Gy using the 10 MV photon beam of a medical linear accelerator under a constant dose rate. The polymerization of NMPA dosimeters occurs and increases monotonically with increasing absorbed dose. Nuclear magnetic resonance (NMR) was used to investigate the degree of polymerization of gels. The dose response in terms of spin–spin relaxation rate (R2) of NMPA dosimeters increased with the addition of glycerol. The influence of the x-ray radiation energy, dose, and dose rate, as well as the stability of the irradiated NMPA gel dosimeters were studied in order to show this preliminary study is indicative of a promising low-toxicity polymer gel dosimeter.

ATF5 involved in radioresistance in nasopharyngeal carcinoma by promoting epithelial-to-mesenchymal phenotype transition.

This study aimed to investigate the effects of activating transcription factor-5 (ATF5) on nasopharyngeal carcinoma (NPC) cell radioresistance. HONE-1 nasopharyngeal carcinoma cells were irradiated by conventional fractionation to generate HONE-1R radiotherapy-resistant cells. Short hairpin RNA (shRNA) expression plasmids targeting the ATF5 gene were constructed and transfected into the HONE-1R cell line. The proliferation assay, colony formation analysis, Transwell Boyden chamber assay and other experimental methods were performed to verify changes in the radiosensitivity and other biological of NPC cells. X-ray irradiation significantly promoted the upregulation of ATF5 protein levels in HONE-1 cells, and the protein expression of ATF5 increased with the dose of X-ray irradiation (p < 0.05). The colony formation rate, cell survival rate and migration ability of HONE-1R cells were significantly higher than those of HONE-1 cells (p < 0.05). Simultaneously, X-ray could also promote the morphology of epithelial-mesenchymal transition (EMT) in HONE-1 cells, inducing a lower expression level of E-cadherin and a higher expression level of N-cadherin in a dose-dependent manner (p < 0.05). Inhibiting ATF5 significantly reduced the colony formation rate, cell survival rate, migration and invasiveness of HONE-1R cells (p < 0.05). Moreover, sensitizing HONE-1R cells to X-ray irradiation significantly upregulated the expression of E-cadherin and downregulated the expression of N-cadherin in these cells (p < 0.05). ATF5 may be a potential therapeutic target to improve radiosensitivity in NPC.

Aspergillus niger Spores Are Highly Resistant to Space Radiation.

The filamentous fungus Aspergillus niger is one of the main contaminants of the International Space Station (ISS). It forms highly pigmented, airborne spores that have thick cell walls and low metabolic activity, enabling them to withstand harsh conditions and colonize spacecraft surfaces. Whether A. niger spores are resistant to space radiation, and to what extent, is not yet known. In this study, spore suspensions of a wild-type and three mutant strains (with defects in pigmentation, DNA repair, and polar growth control) were exposed to X-rays, cosmic radiation (helium- and iron-ions) and UV-C (254 nm). To assess the level of resistance and survival limits of fungal spores in a long-term interplanetary mission scenario, we tested radiation doses up to 1000 Gy and 4000 J/m2. For comparison, a 360-day round-trip to Mars yields a dose of 0.66 ± 0.12 Gy. Overall, wild-type spores of A. niger were able to withstand high doses of X-ray (LD90 = 360 Gy) and cosmic radiation (helium-ion LD90 = 500 Gy; and iron-ion LD90 = 100 Gy). Drying the spores before irradiation made them more susceptible toward X-ray radiation. Notably, A. niger spores are highly resistant to UV-C radiation (LD90 = 1038 J/m2), which is significantly higher than that of other radiation-resistant microorganisms (e.g., Deinococcus radiodurans). In all strains, UV-C treated spores (1000 J/m2) were shown to have decreased biofilm formation (81% reduction in wild-type spores). This study suggests that A. niger spores might not be easily inactivated by exposure to space radiation alone and that current planetary protection guidelines should be revisited, considering the high resistance of fungal spores.

Development of a scanning soft X-ray spectromicroscope to investigate local electronic structures on surfaces and interfaces of advanced materials under conditions ranging from low vacuum to helium atmosphere.

A scanning soft X-ray spectromicroscope was recently developed based mainly on the photon-in/photon-out measurement scheme for the investigation of local electronic structures on the surfaces and interfaces of advanced materials under conditions ranging from low vacuum to helium atmosphere. The apparatus was installed at the soft X-ray beamline (BL17SU) at SPring-8. The characteristic features of the apparatus are described in detail. The feasibility of this spectromicroscope was demonstrated using soft X-ray undulator radiation. Here, based on these results, element-specific two-dimensional mapping and micro-XAFS (X-ray absorption fine structure) measurements are reported, as well as the observation of magnetic domain structures from using a reference sample of permalloy micro-dot patterns fabricated on a silicon substrate, with modest spatial resolution (e.g. ∼500 nm). Then, the X-ray radiation dose for Nafion® near the fluorine K-edge is discussed as a typical example of material that is not radiation hardened against a focused X-ray beam, for near future experiments.

Ultrasensitive and stable X-ray detection using zero-dimensional lead-free perovskites

Abstract Sensitive and reliable X-ray detectors are essential for medical radiography, industrial inspection and security screening. Lowering the radiation dose allows reduced health risks and increased frequency and fidelity of diagnostic technologies for earlier detection of disease and its recurrence. Three-dimensional (3D) organic–inorganic hybrid lead halide perovskites are promising for direct X-ray detection – they show improved sensitivity compared to conventional X-ray detectors. However, their high and unstable dark current, caused by ion migration and high dark carrier concentration in the 3D hybrid perovskites, limits their performance and long-term operation stability. Here we report ultrasensitive, stable X-ray detectors made using zero-dimensional (0D) methylammonium bismuth iodide perovskite (MA3Bi2I9) single crystals. The 0D crystal structure leads to a high activation energy (Ea) for ion migration (0.46 eV) and is also accompanied by a low dark carrier concentration (~ 106 cm−3). The X-ray detectors exhibit sensitivity of 10,620 µC Gyair−1 cm−2, a limit of detection (LoD) of 0.62 nGyair s−1, and stable operation even under high applied biases; no deterioration in detection performance was observed following sensing of an integrated X-ray irradiation dose of ~23,800 mGyair, equivalent to > 200,000 times the dose required for a single commercial X-ray chest radiograph. Regulating the ion migration channels and decreasing the dark carrier concentration in perovskites provide routes for stable and ultrasensitive X-ray detectors.

Ionizing radiation modulates vascular endothelial growth factor expression through STAT3 signaling pathway in rat neonatal primary astrocyte cultures.

Background and PurposeRadiation‐induced brain injury (RBI) usually occurs six months to three years after irradiation, often shows cognitive dysfunction, epilepsy, and other neurological dysfunction. In severe cases, it can cause a wide range of cerebral edema, even herniation. It seriously threatens the survival of patients and their quality of life, and it becomes a key factor in limiting the radiation dose and lowering the therapeutic efficacy in recent years. Therefore, studying the pathogenesis of RBI and exploring new therapeutic targets are of great significance.MethodsIn our study, we observed the activation and secretory function in astrocytes as well as the intracellular signal transducer and activator of transcription 3 (STAT3) signal transduction pathway activation status after exposing different doses of X‐ray irradiation by using MTT, Immunocytologic analysis, and Western blot analysis. Further, we used the same way to explore the role of vascular endothelial growth factor (VEGF) in signal transduction pathways playing in the activation of astrocytes after irradiating through the use of specificInhivascular endothelial growth factorbitors of STAT3.ResultsAst can be directly activated, reactive hyperplasia and hypertrophy, the expression of the activation marker glial fibrillary acidic protein is increased, and the expression of vascular endothelial growth factor (VEGF) in the cells is increased, which may lead to RBI. After the addition of STAT3 pathway inhibitor, most of the Ast radiation activation was suppressed, and the expression of high‐level expression of VEGF decreased after irradiation.ConclusionOur findings demonstrated that X‐ray irradiation directly induced the activation of astrocytes in a persistent manner and X‐ray irradiation activated STAT3 signaling pathway. As the same time, we found that X‐ray irradiation induced the activation of astrocytes and secretion cytokine. The STAT3 signaling pathway may participate in the pathogenesis of radiation‐induced brain injury.

Evaluation of structural behaviour, radioluminescence, Judd-Ofelt analysis and thermoluminescence kinetic parameters of Eu3+ doped TTB–type lead metaniobate phosphor

In this study, the structural and spectroscopic properties of orthorhombic PbNb2O6 doped with different concentrations of Eu3+ were studied. Interestingly, XRD analysis of undoped PbNb2O6 showed rhombohedral phase while Eu3+ doped structures exhibited an orthorhombic phase at 1250 °C. This difference was also observed in the morphology and composition of grains by SEM-EDS analysis. PL and RL emissions occurred between 550 and 850 nm owing to the 4f–4f transitions of Eu3+. The Judd-Ofelt theory was applied to the experimental data for determination of the Judd-Ofelt parameters (Ω2, Ω4), radiative transition rates (Ar) and radiative lifetimes (τr). TL glow curves were monitored by the peaks of 98 and 250 °C while emission increased up to 6 mol%. TL emission of 6 mol% phosphor depending on X-ray irradiation dose exhibited the highest intensity for 1200 Gy and appeared new peaks. Moreover, the TL emission of phosphor showed a linear relation with X-ray irradiation. The deconvolution peaks of 1200 Gy irradiated samples were determined by the CGCD method. Kinetic data of first peak (98 °C) depending on the dose increase were calculated by the PS method.

Radiation induced change in the optical properties of NaCl:Yb crystal

We report the X-ray induced change of optical absorption, photoluminescence, and decay time of a 0.1 mol% Yb-doped NaCl (NaCl:Yb) crystal. The crystal sample can be easily prepared from the melt using a conventional Bridgman technique. The absorption spectra showed at least four peaks at 240, 275, 340, and 380 nm owing to Yb2+, which are consistent with the excitation spectra monitored at 435 nm. The absorption rise in near-infrared owing to Yb3+ drastically decreased with increasing X-ray irradiation dose. The photoluminescence band appeared near the wavelength of 435 nm under excitation at 380 nm, which is due to the transitions from the 4f13 (2F7/2) 5d excited states to the 4f14 (1S0) ground state of Yb2+. The characteristic luminescence intensity of Yb2+ increased with increasing X-ray dose in the range from 0.1 to 100 Gy.

Technical Note: Radiotherapy dose characterization of gel dosimetry using shear wave elasticity imaging.

Radiotherapy is an effective treatment for many types of cancer in clinical settings. Gel dosimetry has the potential to record three-dimensional (3D) dose distribution compared to a conventional ion chamber. As the elasticity of the gel is altered after irradiation due to gel polymerization, we aim to measure the dose recorded in gel dosimetry with ultrasonic shear wave elasticity imaging (SWEI), a nondestructive and quantitative elasticity imaging tool. In this study, a cylindrical N-isopropylacrylamide (NIPAM) polymer gel with a diameter of 10cm and a height of 10cm and with cellulose as an ultrasonic scatterer was irradiated by a linear accelerator with the irradiation parameters of 6MV x-ray, dose rate of 100cGy/min and field size of 10 20mm2 . The six gel phantoms were irradiated with the dose of 0, 1, 3, 5, 8, or 10Gy. The gel phantoms were measured with SWEI at 24, 36, and 48h after x-ray irradiation. The two-dimensional (2D) shear wave velocity and Young's modulus maps corresponding to x-ray dose distribution were reconstructed following a time-of-flight reconstruction from a set of time-series displacement maps. The spatial resolution of the reconstructed SWEI image is ~1mm. Our results show that the elastic modulus increases linearly as irradiation dose increases (R2 =0.94 at 24h, R2 =0.98 at 36h, R2 =0.98 at 48h), suggesting that the gel elasticity is highly associated with x-ray irradiation dose at 36h post irradiation, and the dose resolution was 0.66kPa/Gy. From the 3D elastic modulus maps, the dose distribution along the depth and lateral direction can be reflected in the NIPAM gel dosimetry using SWEI as well. In this study, the irradiated NIPAM gel phantom was quantitatively measured with SWEI for the first time to read the dose distribution recorded in the gel dosimetry. The results suggest that the gel elasticity is highly associated with x-ray irradiation dose. In the future, 2D/or 3D dose distribution from intensity modulated radiotherapy (IMRT) or other potential particle radiotherapy will be measured and reconstructed with SWEI and compared with the dose map from a treatment planning system (TPS) in the clinic.

Monitoring the Absorption Dose of X-ray Radiation on the Thoracic Examination

The study of monitoring the absorption dose of X-ray radiation received by thoracic examination patients has been conducted. The absorbance dose received by the patient is calculated from the exposure factor data consisting of electric voltage (kV), current (mA), time (s), and examination distance (m). Data were obtained from 130 male patients and 60 female patients, who performed thoracic examinations in a Posterior Anterior (PA) position. The absorbed dose received by male and female patients is compared with the maximum absorbed dose determined by BAPETEN for thoracic examinations on adult patients, which is 0.4 mGy. Differences in the absorbed dose received by male and female patients were identified by the T-test of two free samples with a significance level of 0.05. The results showed that the dose of X-ray radiation received by male and female patients was still below the maximum absorbed dose determined by BAPETEN, and the results of the T-test showed no significant difference in the absorbed dose received by male and female patients.

Degradation study of arsenic oxides under XPS measurements

XPS is extensively used for the characterization of arsenic-containing compounds like As(V) oxides, which can be found on the surface of minerals and important functional materials such as semiconductors and catalysts. However, potential sample degradation could alter the results. In this study, we explore the nature and extent of As2O5.5/3H2O phase degradation under XPS measurements in order to assess the intrinsic impact of this spectroscopic technique on the collected data. A series of experiments were designed for unravelling the effect of several factors like X-ray.irradiation time and intensity, vacuum time and charge compensation system. The influence of the structure and composition of the oxide was tested by taking the As2O5 phase as reference. Analyses were based on curve fitting of As3d, C1s and O1s high-resolution spectra, including survey quantification. Results show that degradation involves reduction of As(V) to As(III) species along with oxygen lost from the oxide lattice. As(V) photoreduction becomes extensive by repeating doses of X-ray irradiation; the photon beam intensity plays a major role in degradation, especially combined with the use of a dual flood gun as charge compensation system, while longer vacuum times also favor reduction. The dehydrated phase is more resistant to degradation likely due to a broader valence-band width. The presence of organic molecules from carbon contamination seems to play an important role in degradation. The possible underlying mechanism based on Auger decay of the initial core hole is considered. Minimal sample damage can be obtained by fixing the operating power and the vacuum and irradiation times at the least affordable values.

Effect of tin filter-based spectral shaping CT on image quality and radiation dose for routine use on ultralow-dose CT protocols: A phantom study

PurposeThe purpose of this study was to assess the impact of tin filter (TF) on X-ray beam quality, image quality and radiation dose and its suitability for routine use for chest and lumbar-spine/pelvis-hip ultralow-dose (ULD) CT examination protocols. Materials and methodsThe X-ray beam quality was determined by measuring the half-value layer (HVL) and calculating the mean weighted energy for 100, 120, 150kVp (using standard filtration) and for 100 and 150kVp using TF (Sn100kVp and Sn150kVp, respectively). Acquisitions were performed on a phantom at four dose levels for each previously definedkVp. The mean attenuation (NCT), noise-power-spectrum (NPS) and task-based transfer function (TTF) were computed. The detectability index (d’) was computed to model the detection of two lesions in spine and pelvic/hip examination and two for chest exploration. Image quality and detectability using a TF were assessed for two routinely used ULD protocols. ResultsThe HVL and mean weighted energy increased using a TF for the same tube voltage. Using a TF for the same tube voltage changed NCT for bone and acrylic inserts, decreased the NPS peak without changing the NPS spatial frequency and increased the TTF values. The d’ values were improved using a TF and with the dose increase. d’ values of all modeled lesions were improved using Sn100kVp and Sn150kVp for the lumbar-spine/pelvis-hip and chest ULD protocols except for sclerotic bone lesion using Sn150kVp. ConclusionThe use of TF increases the X-ray beam quality and improves the image quality characteristics in phantom images, thus appearing as a promising tool for reducing dose and/or improving the image quality of ULD protocols.

Effects of different doses of X-ray radiation on nerve regeneration after sciatic nerve injury in a rat model

Effects of different doses of X-ray radiation on nerve regeneration after sciatic nerve injury in a rat model

Nonlinear Conductivity of ZnO Materails Induced by X Ray

Due to high energy electron radiation in space, Spacecraft internal charging will occur, which will cause deep dielectric electrostatic discharge and cause the most serious anomalies, that is, those that have resulted in the loss of mission. Because spacecraft internal charging is accompanied with X-ray bremsstrahlung, it is possible to mitigate inner dielectric electrostatic discharge by using nonlinear conductivity material induced by X-ray radiation. It shows that the conductivity of ZnO materials increases with the increase of X-ray radiation dose rate. At low X-ray radiation dose rate, the conductivity of ZnO increases linearly with the increase of X-ray dose rate. At high X-ray radiation dose rate, the conductivity of ZnO is saturated gradually. The conductivity of ZnO with high original resistivity varies more widely with the dose rate of X-ray, which is more suitable for spacecraft internal charging protection.