Al Filter Research Articles

INVESTIGATION OF X-RAY EMISSION FROM LASER PRODUCED ALUMINIUM ANTIMONIDE PLASMA

Lasers are integral to numerous applications in our daily lives, with one of their notable uses being the ablation of materials to generate plasma, which in turn produces X-rays with a variety of applications. This study investigates the generation of hard X-rays from Aluminum Antimonide (AlSb) plasma, induced by a Q-switched Nd: YAG laser operating at 1064[Formula: see text]nm with a pulse duration of 9–14[Formula: see text]ns and a peak power of 1.1[Formula: see text]MW. The AlSb target was selected due to its unique electronic structure and high atomic number, which are advantageous for efficient X-ray generation. At a tight focus, the laser produced a spot size of 11.8 micrometers, achieving an intensity of 1012 W/cm[Formula: see text], to study the transmission of hard X-rays both in a vacuum environment with a pressure of 10[Formula: see text] torr and in air at atmospheric pressure. A Photo Multiplier Tube (PMT) was employed to detect the transmitted hard X-rays, which were filtered using a 10 [Formula: see text]m-thick Al filter. The fundamental mechanisms behind the emission of hard X-rays from laser-induced AlSb plasma were explored. Plasma plume expansion and the energy of the emitted radiation were found to depend on the number of laser pulses and the ambient pressure. The intensity of the plasma plume was observed to be inversely proportional to the ambient pressure and directly proportional to the number of laser pulses fired. Plasma confinement under high pressures was also examined. Time-resolved studies of the hard X-ray emission contributed to the analysis. The relationship between different laser shots and the current, voltage, and energy of the hard X-rays, as well as their inverse proportionality to ambient pressure, was quantified. At an ambient pressure of 10[Formula: see text] torr, the dynamics of the AlSb plasma plume were observed. The surface morphology of the laser-irradiated AlSb target was also analyzed, revealing unique properties pertinent to X-ray emission.

Enhanced laser absorption and ion acceleration by boron nitride nanotube targets and high-energy PW laser pulses

Enhancing laser energy absorption with energy transfer to fast electrons is crucial for efficient laser-driven ion acceleration. In this work, we present an experimental demonstration of volumetric laser absorption using boron nitride nanotube (BNNT) targets with an average density of 15 of the solid density. We use a PW laser system operating at a pulse duration of 1.2 ps and an energy of 1.3 kJ, reaching intensities of 2 × 1019 Wcm−2 on target with moderate nanosecond contrast (109), to generate energetic ion streams from a 250 µm thick BNNT target. To characterize laser-accelerated ions, Thomson parabola spectrometers, CR-39 nuclear track detectors, and an electron spectrometer are employed. The results are compared to those achieved using flat targets made of polystyrene (PS) of the same thickness. The comparison reveals a 1.5-fold increase in proton maximum energy and a 2.5-fold increase in the maximum energy of heavy ions (C and N) when comparing the BNNT to PS. Moreover, the high-energy ion flux recorded at CR-39 is orders of magnitude higher for the BNNT after cutting off low-energy ions with Al filters. The enhanced ion acceleration is the result of a 2.3-fold increase in the electron temperature for BNNT, as measured by the electron spectrometer. These experimental findings are further validated through two-dimensional particle-in-cell simulations, which confirm the increase in electron temperature due to enhanced laser absorption ascribable to the low density and nanostructure of the BNNT target compared to the flat foil. Published by the American Physical Society 2024

Evaluation of lower detection limit and performance analyses related to the incident angle of X-rays and absolute dose using a triple-type dosimeter

When using a wearable active-type dosimeter for real-time dosimetry during X-ray fluoroscopic procedures, medical staff should be aware of the potential for an inaccurate exposure dose due to the large angular dependence. To address this issue, our research group has proposed a triple-type active dosimeter. With this device, the incident angle of scattered X-rays can be determined based on the signal difference between two dosimeters placed side-by-side, in which the wedge filters on the entrance windows are arranged symmetrically. In addition, the absolute dose can be determined from the central dosimeter with angular dependence correction. Although the concept of using wedge filters was proven in a previous study, the wedge filter materials have not been sufficiently studied. In this study, therefore, we sought to determine which of several materials was best suited as a wedge filter material for medical applications: aluminum (Al), titanium (Ti), or copper (Cu). We analyzed the performance of dosimeters with the different wedge filter materials in terms of estimation accuracy and lower detection limit. Using a clinical fluoroscopic system with a tube voltage of 80 kV, the scattered X-rays generated from an elliptical cylinder water phantom were measured while varying the incident direction of the X-rays from −50° to +50° in 10-degree intervals. The experimental results showed that the incident angles were properly determined when using the Ti filter, but the estimation accuracy was slightly lower when using the Al and Cu filters. The accuracy of absolute dose was evaluated from the standard deviation of the absolute dose data between −50° and +50°. As a result, the accuracies when using the Al, Ti, and Cu filters were 3.6%, 3.9%, and 5.9%, respectively. The lower detection limit when using the Cu filter showed a significantly higher value (0.50 μSv/s), but that with the Ti filter was reasonable (0.07 μSv/s). Based on these experimental evaluations, we concluded that the Ti filter would be suitable for use in a triple-type dosimeter. Finally, we investigated the expected dose rates of scattered X-rays in various interventional radiology (IVR) procedures described in the literature and determined that our dosimeter could be used for actual dose measurement.

Dose optimization in newborn abdominal radiography: Assessing the added value of additional filtration on radiation dose and image quality using an anthropomorphic phantom

BackgroundAbdominal radiographs remain useful in newborns. Given the high radiation sensitivity of this population, it is necessary to optimize acquisition techniques to minimize radiation exposure. ObjectiveEvaluate the effects of three additional filtrations on radiation dose and image quality in abdominal X-rays of newborns using an anthropomorphic phantom. Material and methodAbdominal radiographs of an anthropomorphic newborn phantom were performed using acquisition parameters ranging from 55 to 70 kV and from 0.4 to 2.5 mAs, without and with three different additional filtrations: 0.1 mm copper (Cu) + 1 mm aluminum (Al), 0.2 mm copper + 1 mm aluminum, and 2 mm aluminum. For each X-ray the dose area product (DAP) was measured, the signal-to-noise ratio (SNR) was calculated, and image quality (IQ) was evaluated by two blinded radiologists using the absolute visual grading analysis (VGA) method. ResultsAdding an additional filtration resulted in a significant reduction in DAP, with a decrease of 42% using 2 mm Al filtration, 65% with 0.1 mm Cu + 1 mm Al filtration, and 78% with 0.2 mm Cu + 1 mm Al filtration (p < 0.01). The addition of 2 mm aluminum filtration does not significantly decrease the SNR (p = 0.31), CNR (p = 0.52) or the IQ (p = 0.12 and 0.401 for reader 1 and 2, respectively). However, adding copper-containing filtration leads to a significant decrease in, SNR, CNR and IQ. ConclusionAdding a 2 mm Al additional filtration for abdominal radiographs in newborns can significantly reduce the radiation dose without causing a significant decrease in image quality.

A carbon nanotube x-ray source array designed for a new multisource cone beam computed tomography scanner

Cone beam computed tomography (CBCT) is known to suffer from strong scatter and cone beam artifacts. The purpose of this study is to develop and characterize a rapidly scanning carbon nanotube (CNT) field emission x-ray source array to enable a multisource CBCT (ms-CBCT) image acquisition scheme which has been demonstrated to overcome these limitations. A CNT x-ray source array with eight evenly spaced focal spots was designed and fabricated for a medium field of view ms-CBCT for maxillofacial imaging. An external multisource collimator was used to confine the radiation from each focal spot to a narrow cone angle. For ms-CBCT imaging, the array was placed in the axial direction and rapidly scanned while rotating continuously around the object with a flat panel detector. The x-ray beam profile, temporal and spatial resolutions, energy and dose rate were characterized and evaluated for maxillofacial imaging. The CNT x-ray source array achieved a consistent focal spot size of 1.10 ± 0.04 mm × 0.84 ± 0.03 mm and individual beam cone angle of 2.4° ± 0.08 after collimation. The x-ray beams were rapidly switched with a rising and damping times of 0.21 ms and 0.19 ms, respectively. Under the designed operating condition of 110 kVp and 15 mA, a dose rate of 8245 μGy s−1 was obtained at the detector surface with the inherent Al filtration and 2312 μGy s−1 with an additional 0.3 mm Cu filter. There was negligible change of the x-ray dose rate over many operating cycles. A ms-CBCT scan of an adult head phantom was completed in 14.4 s total exposure time for the imaging dose in the range of that of a clinical CBCT scanner. A spatially distributed CNT x-ray source array was designed and fabricated. It has enabled a new multisource CBCT to overcome some of the main inherent limitations of the conventional CBCT.

ПОСТРАДИАЦИОННЫЕ ИЗМЕНЕНИЯ КОЛИЧЕСТВА ФОКУСОВ ФОСФОРИЛИРОВАННЫХ БЕЛКОВ H2AX И AТМ В МЕЗЕНХИМАЛЬНЫХ СТВОЛОВЫХ КЛЕТКАХ ЧЕЛОВЕКА, ОБЛУЧЕННЫХ РЕНТГЕНОВСКИМ ИЗЛУЧЕНИЕМ В МАЛЫХ ДОЗАХ

Aim: To study the patterns of changes in the number of foci of phosphorylated DNA double-strand break repair proteins H2AX (γH2AX) and ATM (pATM) in cultured human mesenchymal stem cells (MSCs) 1‒48 hours after exposure to X-ray radiation at doses of 40, 80, 160 and 250 mGy. Material and methods: We used the primary culture of human MSCs, obtained from the collection of LLC “BioloT” (Russia). Cells were irradiated using a RUB RUST-M1 X-ray biological unit (Diagnostika-M LLC, Moscow, Russia) equipped with two X-ray emitters at a dose rate of 40 mGy/min (voltage of 100 kV, an anode current of 8 mA, and a 1.5 mm Al filter) and 4 °C temperature. To quantify the yield of γH2AX and pATM foci immunocytochemical staining was carried out with the use of γH2AX and pATM antibody respectively. Statistical analysis of the obtained data was carried out using the statistical software package Statistica 8.0 (StatSoft). To assess the significance of differences between samples, Student’s t-test was used. Results: It was shown that the kinetics of changes in the number of γH2AX foci after irradiation at doses of 160 and 250 mGy and low (40‒80 mGy) doses are significantly different. In contrast to the significant (50‒60 %) decrease in the number of γH2AX foci observed 6 hours after irradiation at doses of 160 and 250 mGy, after irradiation at low doses, no significant decrease in γH2AX foci was observed at this time point. Analysis of the colocalization of γH2AX foci with pATM foci indicates that the mechanisms for maintaining a high number of γH2AX foci 24‒48 hours after low-dose irradiation are ATM independent. A hypothesis has been put forward to explain the phenomenon of maintaining the number of γH2AX foci 24‒48 hours after irradiation in low doses by replicative stress caused by stimulation of proliferation against the background of hyperproduction of free radicals, resulting in additional formation of DNA double-strand breaks and phosphorylation of H2AX by ATR kinase.

Optimization of parameters for portable X-ray diffraction/X-ray fluorescence combined analysis device (P-XRDF-CAD)

This paper aims to optimize the parameters of a portable device that combines X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis techniques. By using the same X-ray source and detector, the device enables the simultaneous acquisition of two-dimensional XRD and XRF information from a sample with the advantage of high analysis efficiency and consistency in the measurement points. The equipment and slit materials are discussed, including the selection of the X-ray source (Moxtek MAGNUM) and the detector (Andor CCD camera). We also explore two different slit designs (the bottom-hole and side-hole) and optimize their dimensions using rectangular holes instead of inclined trapezoidal holes. Considering the fluorescence X-rays of the filters in the X-ray tube spectra, a theoretical formula is derived for rapid and accurate calculation. The calculated results are compared with the experimental results of Al and Ni filters, demonstrating good agreement across various tube voltages and filter thicknesses. Furthermore, an XRD/XRF comprehensive analysis platform is established. The effects of tube voltage, tube current, exposure time, and pixel-binning on the single-pixel events of the CCD camera are investigated and can be used to guide the selection of appropriate device parameters. The effects of the frame and tube voltage on the XRD/XRF analysis efficiency are examined for several sample materials, including Al, α-Fe, Zn, and ZrO2(Y2O3).

A new formula for converting dose-area product to effective dose in dental cone-beam computed tomography

PurposeThe purpose of this study was to determine a dedicated conversion formula between dose-area product (DAP) and effective dose (E) for dental CBCT, which incorporates X-ray beam energy as well as geometric factors. MethodsCBCT exposures of an adult phantom were simulated using PCXMC 2.0 (STUK, Finland). Fifty-seven fields of view (FOV) were included, ranging from Ø4x4cm to Ø21x19cm. Six tube voltages (70 kV to 120 kV), eight combinations of Al (2.5 to 10 mm) and Cu (0 to 0.5 mm) filtration, and four source-isocentre distances (35 to 65 cm) were used, resulting in 10 896 simulated scan protocols. In addition, 10 944 random combinations of scan parameters within the aforementioned ranges were simulated, resulting in 21 840 scan protocols that were used for fitting a formula using multiple linear regression with 8 independent variables. Finally, 2304 random scan protocols were simulated as validation data to evaluate the formula’s generalizability. ResultsE/DAP ranged between 0.031 µSv/mGy.cm2 and 0.294 µSv/mGy.cm2, with a mean of 0.150 µSv/mGy.cm2. Due to extensive clustering of the E/DAP, three formulas were determined according to FOV categories (Small: <100 cm2, Medium: 100–400 cm2, Large: >400 cm2). The resulting formulas showed mean absolute errors of 7.9%, 4.0% and 3.6%, respectively, for the validation data. ConclusionThe new formulas allow for a straightforward, yet accurate, estimation of the effective dose for dental CBCT based on DAP. Further fine-tuning of the model could be achieved by incorporating, for example, bowtie filtration and off-axis beam geometries.

Effect of varying X-ray tube voltage and additional filtration on image quality and patient dose in digital radiography system

This study investigated the effect of varying x-ray tube voltage and additional filtration thicknesses on radiation dose and image quality in digital radiography system. The polymethylmethacrylate (PMMA) phantoms of different thicknesses simulating both the adult chest and abdomen and the pediatric patient's chest examinations were used. X-ray tube voltage range of 70–125 kVp was used for adult patient chest radiography, 70–100 kVp for adult patient abdominal radiography, and 50–70 kVp for pediatric 1-year-old chest examination. 0.1–0.3 mm Cu and 1.0 mm Al filters were used as additional filters. Patient doses were measured with an ionization chamber, considering the irradiation parameters recommended for radiographic examinations performed in radiology clinics in the EUR 16260 protocol. The Entrance Skin Dose (ESD) was calculated from the air kerma value measured at the entrance surface of the PMMA phantoms. Effective dose values were calculated by employing PCXMC 2.0 program. For image quality evaluations, CDRAD, LCD-4, Beam stop and Huttner test object used together with PMMA phantoms and Alderson RS-330 Lung/Chest phantom were used. Figure of Merit (FOM), which allows quantitative assessment in terms of image quality and patient dose, has been calculated. Based on the calculated FOM values were evaluated at the tube voltages and additional filter thicknesses recommended in the EUR 16260 protocol. Entrance Skin Dose and Inverse Image Quality Figure (IQFinv) value obtained from contrast detail analysis decreased with increasing filter thickness and tube voltage. Decrease in ESD and IQFinv with increasing tube voltage without additional filter was 56% and 21% for adult chest radiography, 69% and 39% for adult abdominal radiography and 34% and 6% for 1-year-old pediatric chest radiography. When calculated FOM values are examined, it can be recommended to use a 0.1 mm Cu filter at 90 kVp and a 0.1 mm Cu + 1.0 mm Al filter at 125 kVp for adult chest radiography. For adult abdominal radiography, 0.2 mm Cu filter at 70 and 80 kVp and 0.1 mm Cu filter at 90 and 100 kVp were found to be appropriate. It was determined that the appropriate additional filter at 70 kVp for 1-year-old chest radiography was 1.0 mm Al+0.1 mm Cu.

Theoretical comparison and optimization of cadmium telluride and gallium arsenide photon-counting detectors for contrast-enhanced spectral mammography.

Most photon-counting detectors (PCDs) being developed use cadmium telluride (CdTe), which has nonoptimal characteristic x-ray emission with energies in the range used for breast imaging. New PCD using a gallium arsenide (GaAs) has been developed. Since GaAs has characteristic x-rays lower in energy than those of CdTe, it is hypothesized that this new PCD might be beneficial for spectral x-ray breast imaging. We performed simulations using realistic mammography x-ray spectra with both CdTe and GaAs PCDs. Five different experiments were conducted, each comparing the performance of CdTe and GaAs: (1) sensitivity of iodine quantification to charge cloud size and electronic noise, (2) effect of photon spectrum on iodine quantification, (3) effect of varying the number of energy bins, (4) a dose analysis to assess any possible dose reduction from using either detector, and (5) spectral performance of ideal CdTe and GaAs PCDs. For each study, 3 sets of 5000 noise realizations were used to calculate the Cramer-Rao lower bound (CRLB) of iodine quantification. For all spectra studied, GaAs gave a lower CRLB for iodine quantification, with 10 of the 12 spectra showing a statistically significant difference ( ). The photon energy spectrum that optimized iodine detection for both detector materials was the 40 kVp beam with 2-mm Al filtration, which produced CRLBs of and for CdTe and GaAs, respectively, when using five energy bins. GaAs is a promising detector material for contrast-enhanced spectral mammography that offers better spectral performance than CdTe.

ВЛИЯНИЕ ЛЕКАРСТВЕННЫХ СРЕДСТВ, НОРМАЛИЗУЮЩИХ КРОВОСНАБЖЕНИЕ И ТРОФИКУ ОБЛУЧЕННЫХ ТКАНЕЙ, А ТАКЖЕ АНТИБИОТИКА ШИРОКОГО СПЕКТРА ДЕЙСТВИЯ НА ТЕЧЕНИЕ ТЯЖЕЛЫХ МЕСТНЫХ ЛУЧЕВЫХ ПОРАЖЕНИЙ У КРЫС

Purpose: To study in the experiment the therapeutic efficacy of drugs that normalize blood supply and trophism of irradiated tissues, as well as a complex broad-spectrum antibiotic, for the course of severe local radiation lesions to justify the clinical use of these drugs in this pathology. Material and methods: Wistar-Kyoto inbred rats were exposed to local X-rays in the ilio-lumbar region of the back at a dose of 110 Gy (tube voltage 30 kV, current 6.1 mA, Al filter 0.1 mm thick), at a dose rate of 20.1 Gy / min. Irradiation field area was 8.5 cm2. Radiation exposure caused the formation of long-term (up to 3.5–4 months) non-healing radiation ulcers of the skin without a critical radiation load on the underlying tissues. For the treatment of radiation lesions, an antibiotic was used – levotetrasulfin forte, as well as drugs that affect the blood supply and trophism of irradiated tissues – pentoxifylline and detralex. The drugs were administered daily both in isolation from each other and together during the period (from the 21st to the 42nd or from the 28th to the 48th day after irradiation), when the radiation ulcer formed and its gradual healing began. The everity of radiation skin lesions and the effects of therapy were assessed in dynamics by clinical manifestations and using planimetry. Results: It was found that the separate use of drugs in the treatment of severe local radiation lesions was not very effective. However, with the combined administration of drugs, a noticeable increase in the rate of healing of radiation ulcers was revealed. Thus, it was shown that with the joint administration of pentoxifylline (intraperitoneal, 50.0 mg / kg), detralex (75.0 mg / kg, per os) and levotetrasulfin forte (intraperitoneal, 0.1 ml / kg), the area of radiation ulcers in treated animals in the period from 98 to 126 days after irradiation was 26–80 % less compared to irradiated controls. Conclusion: The experiments show the possibility of successful use of a complex antibiotic in combination with drugs that improve blood supply and trophism of irradiated tissues, in the treatment of severe local radiation lesions.

Lead equivalence testing using a custom-built testing kit.

Radiation protective garments should undergo a quality assurance regime comprising of an acceptance test of the lead equivalence before the garment is introduced into clinical service, followed by routine periodic visual and fluoroscopic inspections throughout its remaining clinical lifespan. The IEC 61331-1:2014 [1] is the leading standard outlining the methodology for testing of lead equivalence of these garments and forms the basis of the Australian/New Zealand Standards(1999) [2]. This study outlines the design and development of an IEC compliant broad beam lead equivalence testing setup, using an in-house custom-built testing kit (CBTK). The practicality and robustness of this kit was performance tested using lead equivalence measurements on 97% pure lead sheets. Hospital radiation protective garments are predominantly made of lead-free or lead-composite materials due to their light weight, as such, a set of lead-free (N-Pb) samples was also performance tested. These samples were tested using two different beam qualities; a total filtration of 2.5 mmAl and 0.25 mmCu added filtration, both at 102 kVp. Samples with thicknesses of 0.25mm, 0.35mm and 0.50mm were used. The differential between labelled and measured lead equivalence averaged 3% for both the 'pure-lead' samples and N-Pb samples, with uncertainty of less than 7%. At 102 kVp, the use of Cu or Al filtration has marginal effect on measured lead equivalence for pure lead or N-Pb samples. The efficacy of utilizing the CBTK with a solid-state detector for lead equivalence testing was demonstrated through its ease of use, consistency and precision.

Correlation between X-ray tube current exposure time and X-ray photon number in GATE.

X-ray image quality relies heavily on the emitted X-ray photon number which depends on X-ray tube current and exposure time. To accurately estimate the absorbed dose in an imaging protocol, it is better to simulate the X-ray imaging with a Monte Carlo platform such as GATE (Geant4 Application for Tomographic Emission). Although input of GATE is the X-ray photon number of the simulated X-ray tube, it lacks a good way to setup the photon number for a desired X-ray tube current setting. To provide a method to correlate the experimental X-ray tube current exposure time and the X-ray photon number in GATE. The accumulated radiation dose of a micro-computed tomography (CT) X-ray tube was recorded at different current exposure times with a general-purpose ion chamber. GATE was used to model the experimental microCT imaging system and calculate the total absorbed dose (cGy) in the sensitive volume of the ion chamber with different X-ray photon numbers. Linear regression models are used to establish a correlation between the estimated X-ray photon number and the X-ray tube settings. At first, one model establishes the relationship between the experimentally measured dose and the X-ray tube setting. Then, another model establishes a relationship between the simulated dose and the X-ray number in GATE. At last, by correlating these two models, a regression model to estimate the X-ray output number from an experimental X-ray tube setting (mAs) is obtained. For a typical micro-CT scan, the X-ray tube is operated at 50 kVp and 0.5 mA for a 500 ms exposure time per projection (0.25 mAs). For these X-ray imaging parameters, the X-ray number per projection is estimated to be 3.613×106 with 1.0 mm Al filter. The findings of this work provide an approach to correlate the experimental X-ray tube current exposure time to the X-ray photon number in the GATE simulation of the X-ray tube to more accurately determine radiation dose for an imaging protocol.

ОСОБЕННОСТИ ОПУХОЛЕВЫХ КЛЕТОК ЧЕЛОВЕКА ЛИНИИ HeLa,ВЫЖИВШИХ И ДАВШИХ УСТОЙЧИВЫЙ РОСТ ПОСЛЕ ОСТРОГО РЕНТГЕНОВСКОГО ОБЛУЧЕНИЯ

Purpose: The evaluation of the repair efficiency of DNA double-strand breaks (DSB), proliferative activity and the yield of cytogenetic disorders in human tumor HeLa cells which survived and gave stable growth after acute irradiation at a dose of 15 Gy. Material and methods: HeLa human tumor cell line (cervical carcinoma) was used. Cells were irradiated on an X-ray biological installation RUST-M1 (Russia), equipped with two X-ray emitters, at a dose rate of 0.85 Gy / min, a voltage of 200 kV, a total current of 10 mA, and a 1.5 mm Al filter. To obtain clones of surviving cells (HeLaRR), after acute irradiation at a dose of 15 Gy, cell cultures were incubated under standard CO2 incubator conditions (37 °C, 5 % CO2) for several weeks until well proliferating cells were obtained. Immunocytochemical staining of the foci of the phosphorylated H2AX protein (γH2AX) was used to quantitatively evaluate the residual foci of DNA DSB repair. The micronuclei number was assessed in cytochalasin-B cytokinesis-blocked binucleated cells stained with acridine orange with luminescence microscopy. The doubling time of the cell population was analyzed by the cell growth curves obtained by daily cell counting for five days. The cell cycle stages distribution was assessed by flow cytometry using the propidium iodide dye. All quantitative indicators of the studies were processed using the Student’s t-test for independent samples and the Kolmogorov – Smirnov test. Results: It was revealed that acute irradiation at a high dose leads to the selection of cells with a higher reparative capacity which is confirmed by the low yield of residual foci of DNA DSB repair and MN after testing irradiation at doses of 5 and 10 Gy. A significant decrease in the proliferative activity of cells that survived after acute X-ray irradiation at a dose of 15 Gy was revealed. The doubling time of the population of unirradiated cells at the stage of exponential growth was ~18 hours while for cells that survived after irradiation at a dose of 15 Gy ~42 hours. A change in the cell cycle phases distribution was observed. Conclusion: Thus, acute irradiation at a high dose leads to the selection of cells with a higher reparative capacity which is confirmed by the low yield of residual γH2AX foci and MN after testing irradiation at doses of 5 and 10 Gy. The decrease in proliferative activity was accompanied by a change in the cell cycle phases distribution.

Physical characteristics of the novel transmission-target X-ray equipment for kilovoltage radiation therapy applications

There are two types of X-ray devices: transmission-type and reflection-type. These two types rely on different techniques to generate X-rays. This study aims to explore physical characteristics of transmission-type anode X-ray device. The newly developed transmission-type X-ray device (NanoRay Biotech) was assessed, and the beam quality of the device was determined by measuring the half-value layer (HVL) and energy spectrum. Furthermore, this study measured the percentage depth dose (PDD) and flatness and symmetry using ionization chambers in the PTW MP3-s water tank, and all of the measurements of the field size on the entrance surface of the water phantom was set 10 by 10 cm2. The study also discusses the stability and linearity of the tube voltage (kVp) and the tube current (mAs) of the X-ray tube, and investigates the effect of aluminum (Al) filter on beam quality. The results show that at the same depth, when the source-to-surface distance was reduced, the PDD declined, while the symmetry of the lateral dose profile was within 3%. In addition, the dose output of the X-ray device increased with an increase in kVp or mAs. The HVL was 1.55 and 0.41 mm with and without the Al filter, respectively. The introduction of the filter helped reduce low-energy photons by 23.4% and increased the ratio of the characteristic radiation by 2.22% in the energy spectrum. With the filter, the device can effectively reduce low-energy photons, thereby decreasing the surface dose and increasing the ratio of characteristic radiation. The rapid decline in PDD made the device suitable for the clinical treatment of shallow tumors and the intraoperative radiation therapy for tumor beds.

The impact of improved non-local means denoising algorithm on photon-counting X-ray images using various Al additive filtrations

The filters used in X-ray systems affect the image quality and radiation dose. Although using filters has advantages in terms of image quality and dose, image noise increases because the amount of X-rays in the energy range of the entire area is reduced. Thus, a newly improved non-local means (INLM) denoising algorithm was modeled and applied to X-ray images based on the thickness of the aluminum (Al) filter, which is most commonly used in X-ray imaging systems, to prove its potential use. For X-ray image acquisition, a high-performance cadmium telluride material-based detector and a tube containing Al filters (1-, 3-, and 5-mm thickness) were designed. The proposed INLM denoising algorithm was modeled by including the improved weights for the gradient information for each pixel in the conventional NLM-based equation. When the proposed INLM denoising algorithm was applied to the acquired photon-counting X-ray images, results showed superior performance for both noise characteristics and no-reference-based image evaluation. In particular, we confirmed that when the INLM was applied to X-ray images using 5 mm Al thickness, noise characteristics and no-reference-based evaluation results were improved by approximately 1.36 times and 1.06 times, respectively, compared to the conventional NLM. The study proved that choosing the INLM in photon-counting X-ray images using 5 mm-thick Al filtration is vital for the success of image processing applications.

Bremsstrahlung Generation by 7.5 Mev Electrons in Converters Made of Different Materials

The present paper shows that, besides the technologically complex water-cooled converters made of Ta or W, a simple and efficient converter in the form of air-cooled Mo and Al plates can be fabricated for a number of tasks. The generation of bremsstrahlung by electrons with the energy of 7.5 MeV in the converter plates made of Ta, W, Cu or Mo and in the Al filter was studied by the Monte Carlo method in the PENELOPE software package. The thicknesses range of the plates made of Ta, W, Cu or Mo was chosen on condition that the total mass thickness of the converter and filter made of Al (in g/mm2) provided complete absorption of the primary electrons. It is shown that the photon yields from Mo at mass thicknesses above 25 g/mm2 are higher than those from Ta and W, but the energy transferred from electrons to BS is lower. With the same mass thicknesses of Ta and W converters, practically all characteristics of bremsstrahlung and the absorbed energy in the target are the same. The conditions for cooling the converter elements with water and air are determined for the level of heat release in the converter up to 10 kW. The minimum dimensions of the electron-irradiated region of Ta and Mo converters, cooled by water, are determined. It is shown that with the really existing air compressors taken into account, the permissible heat release of air-cooled Mo converters should not exceed 4 kW.

Long-term changes in Al thin-film extreme ultraviolet filters.

Thin-film Al filters are very popular owing to their high transmittance in the wavelength range of 17-67 nm and low transmittance in the visible and near-UV regions; however, they are prone to oxidation. The amorphous Al2O3 layers on the Al surfaces have much smaller transmittance than the bulk Al material; therefore, they strongly influence the total transmittance of the filter. This paper not only provides the transmittance of very old Al filters but also maps the transmittance development of Al filters over two years since their delivery (in 2016) in an uncontrolled atmosphere.

Determination of DQE as a quantitative assessment of detectors in digital mammography: Measurements and calculation in practice

Abstract Introduction: Advances in digital detector technology and methods of image presentation in digital mammography now offer the possibility of implementing mathematical assessment methods to quantitative image analysis. The aim of this work was to develop new software to simplify the application of the existing international standard for DQE in digital mammography and show in detail how it can be applied, using a Siemens Mammomat Inspiration as a model. Material and methods: Consistent with the IEC standard a 2 mm Al filter at the tube exit and images in DICOM format as raw data, without applying any additional post-processing were used. Measurements were performed for W/Rh anode/filter combination and different tube voltage values (26 ÷ 34 kV) without any anti-scatter grid. To verify new software doses ranging from 20-600 µGy were used in measurements. Exposure (air kerma) was measured using a calibrated radiation meter (Piranha Black 457, RTI Electronics AB, Sweden). MTF was determined, using an edge test device constructed specifically for this work. Results: It has been demonstrated that with the new software the DQE can be measured with the accuracy required by the international standard IEC 62220-1-2. DQE has been presented as a function of spatial frequency for W/Rh anode/filter combination and different tube voltage. Conclusions: New software was used successfully to analyze image quality parameters for the Siemens Mammomat Inspiration detector. This was done on the basis of an internationally accepted methodology. In the next step, mammographs with different detector types can be compared.

Visualization of Commercial Coating Penetration into Fagus crenata Blume Wood Using a Non-Destructive X-ray Microtomography

Coatings can be used as a preservative method to protect the wood, especially the wood surface. The different component of the coating’s dependence of the purpose of it. The Japanese beech (Fagus crenata Blume) applied by several Japanese commercials coating materials. The coatings application used were spray type and brush type. X-ray microtomography in Fuji, Japan was used for visualized the coating samples. The X-ray target used were Cu, and Mo with Al filter. The X-ray image analysis in 2D and 3D were conducted using image J and VGStudio Max, respectfully. The coating’s containing materials and the concentration of it strongly affected the image result of X-ray microtomography visualization. The different X-ray target shows the different image results. The larger energy of X-ray (Mo with Al filter) is recommended to use for visualization. The X-ray images shows the penetration phenomena, which can be applied to calculate the penetration depth.