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Wyszukujesz frazę "Markiewicz, B" wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Validation of the usefulness of dose calculation algorithms in radiotherapy planning system
Autorzy:
Kiełtyka, B.
Rawojć, K.
Kisielewicz, K.
Markiewicz, I.
Powiązania:
https://bibliotekanauki.pl/articles/1065171.pdf
Data publikacji:
2016-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.55.km
87.55.kd
87.10.Rt
87.10.Vg
Opis:
One of the main goals of radiotherapy is to achieve tumor control and minimize probability of normal-tissue complications. For this reason radiation oncology requires high accuracy, which implies no more than 2-3% uncertainty levels in the treatment planning calculations. That is challenging, when heterogeneous tissues such as lungs and bones are involved. To verify the accuracy of the dose calculation algorithms numerous approaches might be performed. The most common are point dose, one-dimensional profile and two-dimensional isodose line comparison with experimental measurements. In presented study, results of transport modeling and the deposited spatial distribution of the dose, obtained by anisotropic analytical algorithm and pencil beam convolution algorithm, were compared to measurements recorded during the experiment. To achieve meaningful conclusions, three parameters: dose difference, distance to agreement and gamma parameter (γ) were taken into consideration and examined. The irradiation was performed using CIRS anthropomorphic phantom. For dose detection gafchromic EBT films were used and scanned after exposure using Epson Scanner. Measured and planned dose distributions were analyzed via FilmQA software. Preliminary results showed that the anisotropic analytical algorithm, with its complex accounting of heterogeneities, provides more accurate dose calculation within an area of a high density gradient, than pencil beam convolution does. The level of the data accuracy derived from the experiment was: dose difference (5%) - 83.4% and 68% pixels passing, distance to agreement (3 mm) - 99.0% and 96.7%, gamma parameter (for dose difference (3%), distance to agreement (3 mm)) - 90% and 75.5%, respectively, for anisotropic analytical algorithm and pencil beam convolution algorithms. The comparison between studied parameters dose difference, distance to agreement and γ for both algorithms implicated anisotropic analytical algorithm as an appropriate approach in radiotherapy treatment planning.
Źródło:
Acta Physica Polonica A; 2016, 129, 2; 219-221
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric Conductivity of $(Bi_{1-x}La_{x}FeO_{3})_{0.5}(PbTiO_{3})_{0.5}$ Ceramics Obtained from Mechanosynthesized Nanopowders
Autorzy:
Markiewicz, E.
Hilczer, B.
Balcerzak, M.
Jurczyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/1375503.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
81.07.Wx
81.20.Ev
75.85.+t
81.40.Rs
Opis:
Electric conductivity of $(Bi_{1-x}La_{x}FeO_{3})_{0.5}(PbTiO_{3})_{0.5}$ ceramics obtained from nanopowders synthesized by high-energy milling from respective oxides was studied in the frequency range 10 mHz ÷ 1 GHz. At room temperatures the low-frequency conductivity was found to be dominated by the contribution from poor-conducting grain boundaries, whereas the contribution in the range 1 kHz ÷ 1 MHz, due to the grain interior, was related by us to the small polaron hopping. Moreover, the electron exchange between ferric and ferrous ions activated at higher frequencies was found to be added to the conductivity above ≈ 1 MHz.
Źródło:
Acta Physica Polonica A; 2014, 126, 4; 971-974
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Nd³⁺ doping on magnetic and dielectric properties of SrFe₁₂O₁₉ hexaferrite synthesized by coprecipitation method
Autorzy:
Hilczer, A.
Pasińska, K.
Markiewicz, E.
Pietraszko, A.
Andrzejewski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1047614.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.60.Ej
75.75.+a
81.20.Fw
Opis:
Magnetic and dielectric properties of hexagonal ferrites important for applications in microwave absorbers are strongly determined by the processing conditions. We studied dielectric and magnetic response of Sr_{1-x}Nd_{x}Fe₁₂O₁₉ (x=0, 0.03, 0.05, 0.07, 0.09) solid solutions obtained by coprecipitation method. The structure of the samples was controlled by X-ray diffraction and scanning electron microscope images revealed that the powder is a mixture of small nanograins and crystallites of 500 nm-1 μm in size. Nd³⁺ doping was found to result in an increase in the coercive field which we would like to relate to the domain wall pinning. The doping-induced changes are monotonous with x up to 0.07. The observed dispersion of permittivity was found to be correlated with the frequency behaviour of electric conductivity of the samples.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 669-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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