Evaluation of CT acquisition protocols effect on Hounsfield units and optimization of CT-RED calibration curve selection in radiotherapy treatment planning systems

O. Nhila$^1$, M. Talbi$^2$, M. El Mansouri$^1$, M. El Katib$^1$, C. El Mahjoub$^1$

The acquisition parameters of a scanner affect the CT number (HU) of the CT images. The degree of effect depends on the change of parameters, the make of scanner, the type of phantom and the density of substitute materials. This work investigates the changes in Hounsfield units (HU) that can result when the acquisition protocol is changed. In the literature, there is a lack of investigation in the area of optimization of the CT-RED calibration curve protocol. A Computerized Imaging Reference System (CIRS) electron density phantom Model 062 was scanned with a HITACHI CT 16 slice Supria scanner, the parameters studied are; Tube voltage, tube current mAs, collimation, slice thickness, field-of-view (FOV), and image reconstruction filters, all parameters are fixed and only one is varied each time to see how this parameter affects the CT number. The tube voltage and the change of reconstruction filter from the body to head, the use of beam hardening correction significantly affects the Hounsfield units in dense bone by a RED of 1.152. For the other substitute materials, the Hounsfield units remained within the tolerances indicated in recent reviews, ±20 HU for soft tissues and ±50 HU for air and bone whatever the parameter varied. In some cases, the acquisition parameters need to be modified according to the morphology of the patient and the region of interest. Therefore, several calibration curves may be included in a TPS, this may increase the risk of incorrect selection of the calibration curve. This work provides a methodology to minimize the number of calibration curves within the tolerances provided in the literature to avoid the risk of incorrect selection of the calibration curve. In this study, three CT-RED calibration curves, are in agreement with all CT spectra used for patient imaging.

A. A. Pryanichnikov$^{1,2}$, A. P. Chernyaev$^2$, M. A. Belikhin$^{1,2}$, P. B. Zhogolev$^1$, A. E. Shemyakov$^1$, I. N. Zavestovskaya$^1$

Proton therapy is one of the rapidly developing types of radiation therapy for oncological diseases. The use of proton imaging, method in which the relative stopping power for protons is reconstructed directly, can significantly increase the accuracy and effectiveness of proton therapy. This paper demonstrates the results of experimental work that was work carried out at the synchrotron of proton therapy complex Prometheus. The optimization of the synchrotron operating mode with low-intensity beam extraction was done for proton radiography and tomography purposes. Data about key changes of the beam extraction parameters for low particles flux as well as low intensity beam control methods was descried.

The group law for the new internal-spacetime mapping between the group of internal electromagnetic gauge transformations and the groups LB1 and LB2 of spacetime tetrad transformations.

A. Garat

In this note we will demonstrate the nature of the group law for the internal-spacetime mapping between the local group of internal electromagnetic gauge transformations and the local groups of tetrad transformations LB1 and LB2 introduced previously. This proof is not trivial and that is why we present the manifest deductions step by step. This map is at the core of grand field unification since it explicitly displays the non-trivial mechanism of tetrad unification between the electromagnetic field and the gravitational field. We will show in a theorem that these mappings between the local internal group of electromagnetic gauge transformations and separately both LB1 and LB2 satisfy the group law.

Yu. A. Eremin$^1$, A. S. Penzar$^2$

In this paper, the diffraction problem of a plane electromagnetic wave on an infinite layered magnetoplasmonic nanocylinder is considered. The resulting effects of spatial dispersion in the golden shell, also known as the nonlocality effects, are taken into account within the framework of the Generalize Nonlocal Optical Response theory. Based on the new scheme of the discrete source method, the influence of particle deformation and the effects of spatial dispersion on the position and amplitude of the maximum energy absorption is analyzed. It is shown that the maximum position can be shifted to the transparency region of human biological tissues due to variations in the thickness of the golden shell and material of the core. It is established that account for the spatial dispersion in the metal shell leads to a decrease in the absorption intensity and a shift of the maximum position to the short-wave region.

M. M. Gubaeva$^1$, R. N. Zhokhov$^2$, K. G. Klimenko$^{1,3}$, T. G. Khunjua$^4$

(2+1)-dimensional Thirring model with 4-component fermions is investigated in the framework of the Hartree-Fock approach. It is shown that its ground state is in fact a mixed phase composed of a phase in which mass of fermions is dynamically generated and chiral invariance is violated spontaneously, as well as a phase in which a $\cP$-odd mass arises dynamically. It was found that dynamic mass generation is possible for any finite number of Fermi-fields.

U. A. Bliznyuk$^{1,2}$, P. U. Borshchegovskaya$^{1,2}$, S. A. Zolotov$^1$, V. S. Ipatova$^2$, G. A. Krusanov$^3$, A. D. Nikitchenko$^1$, F. R. Studenikin$^{1,2}$, A. P. Chernyaev$^{1,2}$

This study presents analytical dependences describe the electron beam spectrum and the dose distribution over the depth of an object when it is irradiated with an accelerated electron beam with an initial energy of 1 to 10 MeV after passing through aluminum plates with a thickness of 1 mm to 5 mm. The developed mathematical model allow to reconstruct the electron beam spectrum after passing through the plates with an error of no more than 10% and the dose depth distributions with an error of no more than 5%.

E. A. Vorobyeva$^{1,3}$, D. O. Peshnina$^{1,2}$, A. A. Tatarintsev$^{1,2}$, A. P. Evseev$^{1,2}$, A. A. Shemukhin$^{1,2}$

Multiwalled carbon nanotubes were obtained by pyrolytic vapor deposition and composites with epoxy resin were synthesized. The Raman spectra show characteristic carbon nanotube peaks on epoxy resin composite samples. The charge characteristics of the obtained samples were studied using an electron probe measuring complex. In samples of composites based on aligned nanotubes with epoxy resin, charging under an electron beam was observed to a much lesser extent. The data obtained demonstrate the possibility of using a polymer composite with oriented nanotubes as an antidynatron coating.

A. E. Ieshkin$^1$, A. D. Zavilgelsky$^{1,2}$, M. E. Beliaev$^1$, A. V. Nazarov$^2$

The temperature dependences of copper sputtering yields by argon cluster ions in the temperature range from 300 K to 1100 K (0.8 of the melting point) were studied by computer simulation using molecular dynamics technique. Argon clusters with a fixed energy of 10 keV had sizes from 50 to 500 atoms. It has been found that as the cluster size increases, i.e., as the specific energy of its atoms decreases, the dependence of the sputtering yield on temperature becomes more pronounced. The results are compared with the thermal spike model.

A. E. Zhitelev, A. V. Kozar

The development of methods for the analysis and synthesis of multilayer periodic structures with specified characteristics is an urgent problem for solving a number of problems in both applied and fundamental physics. Based on the method of coupled wave thicknesses and the algorithm built on its basis, exact analytical relationships were found, including the entire set of structural solutions and allowing the synthesis of multilayer structures with given amplitude-phase characteristics, for any values ​​of the refractive indices, both of the media being matched and the materials of the layers.

I. O. Dzhun, G. V. Babaytsev, A. V. Makunin, I. L. Romashkina, M. G. Kozin, N. G. Chechenin

Trilayer thin-film magnetic structures NiFe/IrMn/NiFe obtained by DC magnetron sputtering in the presence of a constant magnetic field 420 Oe were investigated by ferromagnetic resonance (FMR) technique. The dependences of the exchange bias, misalignment angle between the uniaxial and unidirectional anisotropies, and the FMR linewidth on the thickness of the antiferromagnetic IrMn layer in the range from 2 to 50 nm are compared for samples with hard Ni40Fe60 and soft Ni75Fe25 ferromagnetic layers of the same 10 nm thickness. Using the data of other authors and our previous data for bilayer structures, possible reasons of the observed dependences are discussed.

S. A. Nikitin, I. A. Ovchenkova, M. E. Blinova, I. S. Tereshina

The direct measurements of the magnetocaloric effect (MCE) and calculations of the change in the magnetic entropy of a large group of GdMn1-xTxSi (T = Ti, Fe, Co) compounds with a CeFeSi type structure were carried out. All studied compounds are ordered ferro- or ferrimagnetically in a wide temperature range from 120 K to 390 K. The maximum value of the MCE (DTad = 1.1 K when the external magnetic field changes from 0 to 12 kOe) is observed for the GdFeSi compound. The obtained concentration dependences of the Curie temperatures and MCE values ​​are analyzed under the assumption that the magnetism of the 3d sublattice has a itinerant nature.

E. M. Ibragimova$^1$, M. K. Salakhitdinova$^2$

The paper presents the results of structural studies of glasses of the composition K2ОAl2O3B2O3 with 0.1 to 3.0 wt % Fe2O3 additives, subjected to thermoradiation treatment at irradiation temperatures of samples 423, 473, 523, and 573 K inside the gamma field 60C at dose rate of 236 R/s. X-ray diffraction spectra revealed the crystal structure of nanoscale inclusions of iron oxides phases of magnetite and hematite in the grid glass. SEM showed that gamma irradiation with doses of (0.3-1.0) 106 R reduces the initial surface roughness from 0.5 to 0.1, and thermoradiation treatment polishes the surface to high degree.