Photoneutron and capture gamma dose calculations for a radiotherapy room made of high density concrete

Neutron and capture gamma ray dose equivalent along the maze and entrance door of a radiation therapy room made of high density concrete was calculated using analytical and Monte Carlo methods. The room geometry and the 18 MV photon beam of a Varian 2100C/D linac were simulated using MCNPX MC code. Four analytical methods including Kersey, French, McCall, and Wu-McGinley methods were used in the current study. Average difference of 13-30% was seen between analytical and MC methods along the maze for photoneutron calculations. The difference between Wu-McGinley and MC methods was about 17% for capture gamma ray calculations. It was concluded that the analytical methods overestimate both neutron and capture gamma ray dose equivalents compared to MC. Moreover, it was shown that the analytical methods can be used as conservative estimators for neutron and capture gamma calculations.

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Gantry orientation effect on the neutron and capture gamma ray dose equivalent at the maze entrance door in radiation therapy

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp1201070g ◽

2012 ◽

Vol 27 (1) ◽

pp. 70-74 ◽

Cited By ~ 3

Author(s):

Hosein Ghiasi ◽

Asghar Mesbahi

Keyword(s):

Monte Carlo ◽

Radiation Therapy ◽

Gamma Ray ◽

Mean Value ◽

Gamma Dose ◽

Monte Carlo Code ◽

Dose Calculations ◽

Entrance Door ◽

Therapy Room ◽

Gantry Angle

In the present study, the effect of gantry orientation on the photoneutron and capture gamma dose calculations for maze entrance door was evaluated. A typical radiation therapy room made of ordinary concrete was simulated using MCNPX Monte Carlo code. Gantry rotation was simulated at eight different angles around the isocenter. Both neutron and capture gamma dose vary considerably with gantry angle. The ratios of the maximum to the minimum values for neutron and capture gamma dose equivalents were 1.9 and 1.4, respectively. On the other hand, comparison of the Monte Carlo calculated mean value over all orientations with Monte Carlo calculated neutron and gamma dose showed that the Wu-McGinley method differed by 5% and 2%, respectively. However, for more conservative shielding calculations, factors of 1.6 and 1.3 should be applied to the calculated neutron and capture gamma doses at downward irradiation. Finally, it can be concluded that the gantry angle influences neutron and capture gamma dose at the maze entrance door and it should be taken into account in shielding considerations.

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Mathematical models of Gauss – Kruger projection for calculation of meridians conversion on the plane and scale of the image

Geodesy and Cartography ◽

10.22389/0016-7126-2018-934-4-2-7 ◽

2018 ◽

Vol 934 (4) ◽

pp. 2-7

Author(s):

P.A. Medvedev ◽

M.V. Novgorodskaya

Keyword(s):

Mathematical Models ◽

Analytical Methods ◽

Theoretical Studies ◽

Spherical Trigonometry ◽

Cylindrical Projection ◽

Rectangular Coordinates ◽

In Series ◽

Observational Errors ◽

The Difference

This work contains continued research carried out on improving mathematical models of the Gauss-Krueger projection in accordance with the parameters of any ellipsoid with the removal of points from the axial meridian to l ≤ 6° . In terms of formulae earlier derived by the authors with improved convergence for the calculation of planar rectangular coordinates by geodesic coordinates, the algorithms for determining the convergence of meridians on the plane and the scale of the image are obtained. The improvement of the formulae represented in the form of series in powers of the difference in longitudes was accomplished by separating spherical terms in series and then replacing their approximate sums by exact expressions using the formulae of spherical trigonometry. As in previous works published in this journal [7, 8], determining the sums of the spherical terms was carried out according to the laws of the transverse-cylindrical projection of the sphere on the plane. Theoretical studies are given and formulae are proposed for estimating the observational errors in the results of the derived algorithms. The maximum of observational errors of convergence of meridians and scale, proceeding from the specified accuracy of the determined quantities was established through analytical methods.

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NMR contribution in sub-horizontal well for porosity-permeability heterogeneity characterization in limestones: implications for 3D reservoir prediction and flow simulation in a world class geothermal aquifer

10.5194/egusphere-egu21-1101 ◽

2021 ◽

Author(s):

Maxime Catinat ◽

Benjamin Brigaud ◽

Marc Fleury ◽

Miklos Antics ◽

Pierre Ungemach ◽

...

Keyword(s):

Geothermal Energy ◽

Horizontal Well ◽

Gamma Ray ◽

Flow Simulation ◽

High Density ◽

Reservoir Prediction ◽

Nmr Data ◽

Geothermal Potential ◽

Facies Associations ◽

Deep Geothermal Energy

With around 50 heating networks today operating, the aera around Paris is the European region which concentrates the most heating network production units in terms of deep geothermal energy. In France, the energy-climate strategy plans to produce 6.4TWh in 2023, compared to 1.5TWh produced in 2016. Despite an exceptional geothermal potential, the current average development rate of 70MWh/year will not allow this objective to be achieved, it would be necessary to reach a rate of 6 to 10 times higher. The optimization of the use of deep geothermal energy is a major challenge for France, and in Ile-de-France, which has a population of nearly 12 million inhabitants. This project aims to reconstruct and simulate heat flows in the Paris Basin using an innovative methodology (1) to characterize, predict and model the properties of reservoirs (facies, porosity, permeability) and (2) simulate future circulations and predict the performance at a given location (sedimentary basin) on its geothermal potential. This study focuses on a high density area of well infrastructures around Cachan, (8 doublets, 1 triplet in 56 km2). A new sub-horizontal doublet concept has been recently (2017) drilled at Cachan to enhance heat exchange in medium to low permeability formations. Nuclear Magnetic Resonance (NMR T2) logs have been recorded in the sub-horizontal well (GCAH2) providing information on pore size distribution and permeability. We integrated all logging data (gamma ray, density, resistivity, sonic, NRM T2) of the 19 wells in the area and 120 thin section observations from cuttings to derive a combined electrofacies-sedimentary facies description. A total of 10 facies is grouped into 5 facies associations coded in all the 19 wells according to depths and 10 3rd order stratigraphic sequences are recognized. The cell size of the 3D grid was set to 50 m x 50 m for the XY dimensions. The Z-size depends on the thickness of the sub-zones, averaging 5 m. The resulting 3D grid is composed of a total of nearly 8.105cells. After upscaled, facies and stratigraphic surfaces are used to create a reliable model using the &#8220;Truncated Gaussian With Trends&#8221; algorithm. The petrophysical distribution &#8220;Gaussian Random Function Simulation&#8221; is used to populate the entire grid with properties, included 2000 NMR data, considering each facies independently. The best reservoir is mainly located in the shoal deposits oolitic grainstones with average porosity of 12.5% and permeability of 100 mD. Finally, hydrodynamic and thermal simulations have been performed using Pumaflow to give information on the potential risk of interference between the doublets in the area and advices are given in the well trajectory to optimize the connectivity and the lifetime of the system. NMR data, especially permeability, allow to greater improve the simulations, defining time probabilities of thermal breakthrough in an area of high density wells.

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The Estimation of Small Percentages of Rubber in Fibrous Materials

Rubber Chemistry and Technology ◽

10.5254/1.3543153 ◽

1942 ◽

Vol 15 (3) ◽

pp. 672-677

Author(s):

C. M. Blow

Keyword(s):

Analytical Methods ◽

Organic Material ◽

Fibrous Materials ◽

Inorganic Substances ◽

The Difference

Abstract Rubber is being used in increasing quantity in fibrous materials of all types as a binder or to impart particular and special properties. The percentage of rubber employed varies from 3 to 15 or 20 per cent, and it is becoming of interest and importance to, have analytical methods to estimate with some degree of accuracy the percentage present. This estimation has several difficulties, and no one method can be adopted on account of the difference in behavior of various fibres. The fibre may consist of protein, such as silk, wool and other animal fibre, leather, or cellulose, such as jute, cotton, rayon, paper, kapok, etc. The rubber may be vulcanized or unvulcanized, and partly or completely in the oxidized state. In addition, there may be organic material, such as protein, soap (added as stabilizer for the latex), fats, oils, waxes, dyestuffs and inorganic substances from the fibre, fillers and pigments, coagulants, and so forth—to name only a few possible compositions. The problem appears complex, but may be simplified in some cases by knowing, from the process of manufacture, the definite absence or presence of certain of these likely ingredients.

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Improvement of a high speed and high density data acquisition system for multiple gamma-ray detection

2007 IEEE Nuclear Science Symposium Conference Record ◽

10.1109/nssmic.2007.4436372 ◽

2007 ◽

Author(s):

Atsushi Kimura ◽

Yosuke Toh ◽

Mitsuo Koizumi ◽

Kazuyoshi Furutaka ◽

Tadahiro Kin ◽

...

Keyword(s):

Data Acquisition ◽

High Speed ◽

Gamma Ray ◽

Data Acquisition System ◽

High Density ◽

Acquisition System ◽

Density Data

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LEAKAGE RADIATION FROM A 10MV MEDICAL LINEAR ACCELERATOR : III NEUTRON AND X-RAY DOSE EQUIVALENT DISTRIBUTION IN THE MAZE AND OUTSIDE OF THE ENTRANCE DOOR OF A TREATMENT ROOM

Japanese Journal of Radiological Technology ◽

10.6009/jjrt.kj00003173951 ◽

1984 ◽

Vol 40 (2) ◽

pp. 219-226

Author(s):

SHIGEATSU YAMAGUCHI ◽

KATSUHIKO ABE ◽

HARUYOSHI SHIMIZU

Keyword(s):

Linear Accelerator ◽

Dose Equivalent ◽

X Ray ◽

Medical Linear Accelerator ◽

Treatment Room ◽

Entrance Door ◽

Leakage Radiation

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Variation of class I HLA antigen expression among platelet density cohorts: a possible index of platelet age?

Blood ◽

10.1182/blood.v71.2.516.bloodjournal712516 ◽

1988 ◽

Vol 71 (2) ◽

pp. 516-519

Author(s):

J Pereira ◽

C Cretney ◽

RH Aster

Keyword(s):

Hla Antigens ◽

Antigen Expression ◽

High Density ◽

Class I ◽

Surface Markers ◽

Low Density ◽

Hla Antigen ◽

The Difference ◽

Hla Molecules

Platelet alloantigens and other surface markers were studied in platelet cohorts of different mean density, using monoclonal and polyclonal probes. High density (HD) platelets expressed 12% more P1A1 molecules (46,942) than low density (LD) platelets (41,892). However, LD platelets carried 42% more HLA-A2 molecules (6,267 +/- 184) than HD platelets (4,406 +/- 232) (P less than .01) and 55% more class I HLA antigens (17,034 +/- 2,062 v 11,007 +/- 2,190) (P = .05). The platelet subpopulations did not differ in their content of glycoprotein (GP)IIb/IIIa complex or Baka antigen. The difference in expression of class I HLA antigens on HD and LD platelets is consistent with two possibilities: either class I HLA molecules are acquired from plasma or they are released into plasma as platelets age in circulation. Accordingly, class I HLA molecules may provide a useful marker of platelet age.

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Assessment of radiological risk in the area around surface disposal at Al -Tuwaitha site

Iraqi Journal of Physics (IJP) ◽

10.30723/ijp.v14i30.204 ◽

2019 ◽

Vol 14 (30) ◽

pp. 90-97

Author(s):

Asia H. Al-Mashhadani

Keyword(s):

Health Risk ◽

Hpge Detector ◽

Specific Activity ◽

Gamma Dose ◽

Dose Equivalent ◽

Radiological Risk ◽

Dose Rates ◽

Gamma Dose Rates ◽

Specific Activities

The gamma dose rates and specific activity of 137Cs, 60Co and 40K insamples of soil taken from places near the landfill radiation at Al-Tuwaitha site were measured using a portable NaI(Tl) detector. Theresults of gamma dose rates in samples were ranged from 52.6nGy.h-1 to 131nGy.h-1. Then the specific activity of 137Cs, 60Co and40K in soil were determined using high pure germanium (HPGe)detector. The specific activities were varied from 1.9 to 115500 Bq.kg-1 for 137Cs, from 6.37 to 616.5 Bq. kg-1 for 60Co, and from 3 to839.5 Bq. kg-1 for 40K. The corresponding health risk for the annualeffective dose equivalent varied from 1.85×10-14 to 15.7mSv/y. Theresults were compared with various international recommendations.

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