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Wyświetlanie 1-4 z 4
Tytuł:
A study of the photoneutron dose equivalent resulting from a Saturne 20 medical linac using Monte Carlo method
Autorzy:
Hashemi, F.
Hashemi-Malayeri, B.
Raisali, G.
Shokrani, P.
Sharafi, A.
Powiązania:
https://bibliotekanauki.pl/articles/148191.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
photoneutron
linac
Monte Carlo method
MCNP4C
dose equivalent
Opis:
High energy linacs have several advantages including lower skin dose and higher dose rate at deep sighted tumors. But, at higher energies photonuclear reactions produce neutron contamination. Photoneutron contamination has been investigated from the early days of modern linacs. However, more studies have become possible using Monte Carlo codes developed in recent years. The aim of this study was to investigate the photoneutron spectrum and dose equivalent produced by an 18 MV Saturne linac at different points of a treatment room and its maze. The MCNP4C code was used to simulate the transport of photoneutrons produced by a typical 18 MV Saturne linac. The treatment room of a radiotherapy facility in which a Saturne 20 linac is installed was modeled. Neutron dose equivalent was calculated and its variations at various distances from the center of the X-ray beam was studied. It was noted that by increasing the distance from the center of the beam, fast neutrons decrease rapidly, but thermal neutrons do not change significantly. In addition, the photoneutron dose equivalent was lower for smaller fields. The fast photoneutrons were not recorded in the maze. It can be concluded that the fast photoneutrons are highly attenuated by concrete barrier, while the slow photoneutrons are increased. In addition, increasing the X-ray field size increases the photoneutron dose equivalent around the treatment room and maze. It seems that the walls play an effective role in increasing the photoneutron dose equivalent.
Źródło:
Nukleonika; 2007, 52, 1; 39-43
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neutronic analysis for core conversion (HEU–LEU) of the low power research reactor using the MCNP4C code
Autorzy:
Aldawahra, S.
Khattab, K.
Gorge, S.
Powiązania:
https://bibliotekanauki.pl/articles/971506.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
MNSR reactor
HEU fuel
LEU fuel
MCNP4C code
safety parameters
Opis:
Comparative studies for conversion of the fuel from HEU to LEU in the miniature neutron source reactor (MNSR) have been performed using the MCNP4C code. The HEU fuel (UAl4-Al, 90% enriched with Al clad) and LEU (UO2 12.6% enriched with zircaloy-4 alloy clad) cores have been analyzed in this study. The existing HEU core of MNSR was analyzed to validate the neutronic model of reactor, while the LEU core was studied to prove the possibility of fuel conversion of the existing HEU core. The proposed LEU core contained the same number of fuel pins as the HEU core. All other structure materials and dimensions of HEU and LEU cores were the same except the increase in the radius of control rod material from 0.195 to 0.205 cm and keeping the outer diameter of the control rod unchanged in the LEU core. The effective multiplication factor (κ eff), excess reactivity (ρ ex), control rod worth (CRW), shutdown margin (SDM), safety reactivity factor (SRF), delayed neutron fraction (β eff) and the neutron fl uxes in the irradiation tubes for the existing and the potential LEU fuel were investigated. The results showed that the safety parameters and the neutron fl uxes in the irradiation tubes of the LEU fuels were in good agreements with the HEU results. Therefore, the LEU fuel was validated to be a suitable choice for fuel conversion of the MNSR in the future.
Źródło:
Nukleonika; 2015, 60, 2; 367-371
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of dosimetry parameters of ADVANTAGETM 103Pd brachytherapy seed using MCNP4C computer code
Autorzy:
Ataeinia, V.
Raisali, G.
Sadeghi, M.
Powiązania:
https://bibliotekanauki.pl/articles/148136.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
brachytherapy
103Pd source
dosimetry parameters
MCNP4C
ADVANTAGE TM 103Pd
Opis:
The IsoAid LLC Inc. has been introduced ADVANTAGETM 103Pd brachytherapy seed in 2006. The aim of this work is to determine the dosimetric characteristics of this seed according to AAPM’s recommendation in TG43-U1 using MCNP4C computer code. The dose rate constant has been determined to be 0.694š0.001 cGy.h–1.U–1. The radial dose function has been calculated at distances from 0.25 to 7 cm. Two-dimensional anisotropy function have been calculated at distances from 0.25 to 7 cm and at angles from 0 to 90 degrees centigrade at 10 degrees centigrade increments. The one-dimensional anisotropy function and anisotropy constant have been also calculated. The anisotropy constant in water has been calculated as 0.872š0.001. The results of this investigation are compared with the results of Meigooni et al. obtained by PTRAN code in 2006 and Sowards results obtained by PTRAN code in 2007. The comparison of the dose rate constant and the one-dimensional anisotropy function obtained from the two codes shows good agreement; also the radial dose function at distances lower than 3 cm and the two-dimensional anisotropy function at angles greater than 20 degrees centigrade are in good agreement. But, for the calculated radial dose function at distances beyond 3 cm, we observed differences between our values and Meigooni et al. and Sowards results. Also, differences between the calculated two-dimensional anisotropy function using the two codes for angles smaller than 20 degrees centigrade are considerable. The differences between the results of MCNP4C and PTRAN codes could be related to the different cross-section data libraries used in these two codes.
Źródło:
Nukleonika; 2009, 54, 3; 181-187
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biokinetics and radiation dosimetry for [4-14C] cholesterol in humans
Autorzy:
Marcato, L. A.
Hamada, M. M.
de Mesquita, C. H.
Powiązania:
https://bibliotekanauki.pl/articles/146882.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
[4-14C]-cholesterol
internal dosimetry
dosimetric model
medical internal radiation dose (MIRD)
Opis:
This study proposes a biokinetic model for using in the assessment of the internal dose received by human subjects administered intravenously or orally with [4-14C]-cholesterol. The proposed model includes three systemic pools representing the short-term (T1/2 = 1 d), intermediate-term (T1/2 = 16 d) and long-term (T1/2 = 78 d) physiological exchanges and two excretion pathways: urine and feces. To validate the model, the predicted excretion and absorption of cholesterol was compared with that described in the literature. The radiometric doses were calculated in function of the phantom body mass (M) applying MIRD (medical internal radiation dose) protocol with ANACOMP software. The effective dose coefficients for oral administration were: 2.93×10–10 Sv.Bq–1 (73.3 kg); 3.84×10–10 Sv.Bq–1 (56.8 kg); 6.74 × 10–10 Sv.Bq–1 (33.2 kg) and 7.72 × 10–10 Sv.Bq–1 (19.8 kg). To determinate the dose for intermediate body mass M the polynomial interpolation can be used: Sv.Bq–1 (kg) = 6 × 10–15M3 – 8 × 10–13M2 + 2 × 10–11M + 6 × 10–10 (R2 ≅ 1). In the same way, for intravenous administration were: 3.72 × 10–10 Sv.Bq–1 (73.3 kg); 4.87 × 10–10 Sv.Bq–1 (56.8 kg); 8.49 × 10–10 Sv.Bq–1 (33.2 kg); 1.26 × 10–9 Sv.Bq–1 (19.8 kg). Similarly, for any M body mass: Sv.Bq–1 (kg) = –4 × 10–15M3 + 9 × 10–13M2 – 7 × 10–11M + 2 × 10–9 can be used.
Źródło:
Nukleonika; 2012, 57, 4; 607-613
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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