Using Cone Beam Computer Tomography for stereotactic space verification during frame-based Leksell Gamma Knife ICON radiosurgery
Using Cone Beam Computer Tomography for stereotactic space verification during frame-based Leksell Gamma Knife ICON radiosurgery
I. I. Bannikova$^1$, A. V. Dalechina$^2$, V. V. Kostjuchenko$^2$
Leksell Gamma Knife frame-based radiosurgery is considered the «gold standard» of neuro radiosurgery. This is due to both the high precision of the radiation treatment and the large amount of the global clinical data gathered over 50 years of using this radiosurgery system. To date, Leksell Gamma Knife Icon is the most modern model of Gamma Knife and provides the ability to conduct a frame -based stereotactic radiation treatment as well as both mask-fixated frameless hypofractionation and radiosurgery . The integrated Cone Beam CT is used for the positional delivery accuracy. Also the CBCT can be used for defining Leksell stereotactic space instead of the traditional stereotactic frame. The purpose of this work is to analyze different studies to investigate the reasons of the observed deviations in the definition of the stereotactic spaces. It was found that the occurrence of the deviations could be associated with the frame placements uncertainties, MR/CT co-registration errors, MRI distortions and the CBCT artifacts.
Show AbstractDetection of 10Be concentration in nuclear power plant construction materials with activation method
Detection of 10Be concentration in nuclear power plant construction materials with activation method
M. V. Zheltonozhskaya$^1$, V. A. Zheltonozhskiy$^2$, D. E. Myznikov$^2$, A. P. Chernyeav$^1$, P. G. Shustov$^1$
The highly toxic 10Be with a half-life T1/2 = 1,6106 years is formed in reactors structural materials. During the process of radioactive decay 10Be emits only electrons with a 555 keV boundary energy. Long-term and expensive radiochemical procedures are required for its detection and control. We propose to use the activation method for determining the 9Be and 10B concentrations in samples with subsequent recalculation of 10Be activity. To implement the proposed method and determine the contribution of 10Be to the structural materials samples, radioactive wastes samples (50 mg) were irradiated with γ-quanta with a 37 MeV boundary energy and 7Be activity in these samples was determined. The activity of 10Be in the sample with a maximum yield of 7Be was 0.09 Bq/g.
Show AbstractOutlook for using of diffusion magnetic resonance imaging in the radiation therapy planning
Outlook for using of diffusion magnetic resonance imaging in the radiation therapy planning
K. A. Urazova$^{1,3}$, G. E. Gorlachev$^2$, A. P. Chernyeav$^3$, A. V. Golanov$^1$
One of the most important stages of therapy planning is the visualization of the pathological target and the surrounding healthy tissues. In cases where critical structures are closely adjacent to a tumor, located inside the pathological target in whole or in part (for example, pituitary adenomas, craniopharyngiomas, optic nerve gliomas), determining the outlines of critical structures from a standard set of images is difficult. In this case, for studying the structure of the brain white matter, another MRI modality, called diffusion-weighted (DWI), can be used, which allows for in vivo measurements of white matter fiber orientation based on information about the diffusion of water. An addition to DWI is diffusion-tensor tomography (DTT), capable of producing quantitative maps of microscopic natural displacements of water molecules that occur in tissues as part of the physical diffusion process. However, now the technique has certain limitations. There are three main problems that prevent the use of DWI by clinicians: 1) high number of false-positive results ; 2) the difficulty with crossing, «kissing» and banding fibers; 3) the lack of reproducibility of the result, dependence on the user; 4) the inability to display paths of small length; 5) the instability of algorithms when working with pathologies. One possible approach that is worth paying attention to in order to improve the results may be machine learning, which consists in using a fully convolutional neural network to study fiber orientation maps. The purpose of the report is literature review of the main diffusion model, tractography algorithms and compare software packages based on them for identifying the necessary functionality to create complete software for radiation therapy.
Show AbstractA method of reducing the dose during the radiation sterilization process of bone grafts
A method of reducing the dose during the radiation sterilization process of bone grafts
V. V. Rozanov$^{1,2}$, A. A. Nikolaeva$^{1,3}$, I. V. Matveychuk$^2$, A. V. Belousov$^1$, D. S. Yurov$^1$, A. P. Chernyeav$^1$
Among all the technologies of bone implant sterilization the most widely used is the radiation sterilization method with gamma rays or electrons. The determining parameter is the value of the absorbed dose. Dose established by the IAEA for sterilization of bone grafts is 25 kGy. One of the largest problems is the dose reduction while preservation of high sterility of the implants. In order to overcome the above drawbacks, an additional sterilizing factor was proposed to use as a sterilization method comprising treating the implant in two steps with an ozone-air mixture, which reduces radioresistance and reduces the population of microorganisms before subsequent radiation processing. Microbiological studies have confirmed the effectiveness of the developed method.
Show AbstractCalculation of α-decay characteristics of superheavy nuclei based on mass relations
Calculation of α-decay characteristics of superheavy nuclei based on mass relations
E. V. Vladimirova$^1$, B. S. Ishkhanov$^{1,2}$, M. V. Simonov$^1$, T. Yu. Tretyakova$^2$
In order to study the stability of the method of local mass ratios in the field of superheavy elements, based on the formula for estimating the residual np-interaction, the binding energies of the nuclei A > 200 are calculated. Comparison with experimental data AME2016 shows high accuracy and stability of the method. The characteristics of α-decay are predicted for Z = 102 − 106 and N = 144 − 157 isotopes.
Show AbstractCharacteristics of pp collision events from ATLAS OpenData
Characteristics of pp collision events from ATLAS OpenData
I. O. Volkov, I. S. Diachkov, L. N. Smirnova, R. A. Shorkin
Parameter distributions for events with W, Z boson and top quark pairs production in ATLAS open data are presented. Comparison of distributions in different ranges of parameters was carried out. Obtained results were compared with public results of ATLAS collaboration.
Show AbstractAnalysis of the crack resistance of adhesive joints using the finite element method and the cohesive zone model
Analysis of the crack resistance of adhesive joints using the finite element method and the cohesive zone model
A. A. Ustinov, P. G. Babaevskiy, N. A. Kozlov, N. V. Salienko
The method of cohesive zones allows us to evaluate the stability of the material, both to the beginning of the growth of an existing crack, and to the occurrence and development of defects in places of stress concentration. The ability to reliably determine the destruction parameters of adhesive joints (AJ) and predict the behavior of structural elements with their use under loading is an important task for the aircraft industry. It is proposed to use in the finite-element 3D model of stratification according to mode I of the AJ sample in the form of a two-console beam, the length of the cohesive zone (lcz) calculated from the experimentally determined parameters — the local interlayer cohesive strength of the material (σIC) and the intensity of release of elastic energy (GIC). The calculated length of the cohesive zone is applied in the model to calculate the minimum number of finite elements at their optimal size, which ensures higher accuracy of calculations of the main parameters of crack resistance of samples of laminated carbon fiber while minimizing the amount of calculations. The objects of study were AJ sheets of aluminum alloy D-16, which were glued together with dispersion-filled adhesives of industrial grades EPK-1, VK-9, and K-300-61, which are widely used as structural adhesives in the production of aerospace structures. As a result of the research, the main parameters of crack resistance were determined and the optimal length of the final cohesive element was selected, and the resulting model accurately describes the process of crack growth. The results obtained correlate well with the results of experiments.
Show AbstractRapid assessment method of temperature-time and deformation-force parameters of a thermally stimulated shape memory effect in polymer composites by dynamic mechanical analysis
Rapid assessment method of temperature-time and deformation-force parameters of a thermally stimulated shape memory effect in polymer composites by dynamic mechanical analysis
A. A. Slyusarev, P. G. Babaevskiy, G. M. Reznichenko, I. G. Agapov
Thermally stimulated shape memory effect (TS SME) in polymer composite materials (PCM) and cross linked polymer matrices is the ability of these materials when heated to a certain temperature, the so-called conversion temperature (Tc), easy to change the shape when an external force is applied, spontaneously restore in the absence of a restraining force and fix the modified and restored form upon cooling. The main factors determining the SME in PCM are: • a large value and reversibility of highly elastic deformations of the matrix at Tc> Tg = Th; • elastic deformations of the reinforcing components (fabric, tape); • freezing of highly elastic deformation at T << Tc. A technique has been developed for the rapid assessment of temperature-time and deformation-force parameters of the TS SME using a dynamic mechanical analyzer (DMA). The technique was tested on carbon plastic with a different type of matrix and fabric as reinforcing. In the developed method for the accelerated evaluation of the deformation-force parameters of the TC SME in PCM at the stages of changing, restoring and fixing their shape, the sample sizes are too small. Therefore, the results obtained can be used only with an accelerated selection of the composition of materials and a comparative assessment of the conditions and effectiveness of the manifestation of the TS SME in them.
Show AbstractThermal modification of cartilage and speckle-modulated images monitoring
Thermal modification of cartilage and speckle-modulated images monitoring
M. L. Novikova$^{1,2}$, A. V. Yuzhakov$^2$, O. I. Baum$^2$
Today non-destructive laser effect on tissue is used in many areas of medicine. By creating a laser-induced temperature field in the cartilage, one can achieve structural rearrangements, the formation of pores and even the shape changes due to the relaxation of mechanical stresses. In the process of laser exposure to cartilage, there is a change in the mechanical and optical properties of the tissue, which must be monitored to adjust the mode of exposure. This is conveniently done using the speckle interferometry method, the idea of which is to observe the interference pattern produced by the interaction of monochromatic coherent radiation with biological tissue. The paper presents the results of a study of the temporal and temperature dependences of the contrast function and cross-correlation. These dependencies can serve as a basis for monitoring laser exposure of tissue in real time.
Show AbstractNumerical modeling of thermal stress in solid-state solar pumped lasers
Numerical modeling of thermal stress in solid-state solar pumped lasers
M. D. Khomenko$^1$, S. D. Payziyev$^2$, K. M. Makhmudov$^2$
A software has been developed and verified for numerical modeling of temperature and thermal stress in crystals of a solar pumped solid-state laser resonator with an external sensitizer for a given volume absorption of radiation. A number of meshes were created for verification. It is shown that the developed solver can be used to calculate thermal stress in solar-pumped laser resonators, and its results for test cases are in good agreement with the analytical solution.
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