Calculated and Measured Depth Dose Profiles in a Phantom Exposed to Neutron Radiation Fields PDF Download
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Languages : en
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An accurate evaluation of doses caused by external sources of neutron radiation depends on knowledge of the transport of radiation inside the human body. Health physicists use two primary methods for studying this radiation transport: computer calculations and measurements. Both computer calculations and measurements were performed under well controlled, nearly identical conditions to determine the extent of their agreement. A comparison of the dose profiles predicted by both measurements and calculations was thus possible. The measurements were performed in a cylindrical phantom made of tissue equivalent plastic. The phantom size, 61 cm high and 30 cm in diameter, was chosen to approximate the human torso and to match the dimensions of cylindrical phantoms used by previous calculations. Holes were drilled down through the phantom to accommodate small tissue equivalent proportional counters (TEPCs) at various depths in the phantom. These counters were used to measure the neutron dose inside the phantom when it was exposed to various sources of neutrons. The holes in the phantom could also accommodate miniature Geiger-Mueller detectors to measure the gamma component of the dose. Neutron and gamma dose profiles were measured for two different sources of neutrons: an unmoderated 252Cf source and a 733-keV neutron beam generated by a Van de Graaff accelerator. 14 refs., 13 figs., 11 tabs.
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Languages : en
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An accurate evaluation of doses caused by external sources of neutron radiation depends on knowledge of the transport of radiation inside the human body. Health physicists use two primary methods for studying this radiation transport: computer calculations and measurements. Both computer calculations and measurements were performed under well controlled, nearly identical conditions to determine the extent of their agreement. A comparison of the dose profiles predicted by both measurements and calculations was thus possible. The measurements were performed in a cylindrical phantom made of tissue equivalent plastic. The phantom size, 61 cm high and 30 cm in diameter, was chosen to approximate the human torso and to match the dimensions of cylindrical phantoms used by previous calculations. Holes were drilled down through the phantom to accommodate small tissue equivalent proportional counters (TEPCs) at various depths in the phantom. These counters were used to measure the neutron dose inside the phantom when it was exposed to various sources of neutrons. The holes in the phantom could also accommodate miniature Geiger-Mueller detectors to measure the gamma component of the dose. Neutron and gamma dose profiles were measured for two different sources of neutrons: an unmoderated 252Cf source and a 733-keV neutron beam generated by a Van de Graaff accelerator. 14 refs., 13 figs., 11 tabs.
Author: C. E. Clifford
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Category :
Languages : en
Pages : 9
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Fast-neutron and associated gamma dose distributions were measured in cylindrical, slab and spherical phantoms of tissue-equivalent material exposed to a broad beam of 2.95-MeV neutrons. The effect of different phantom geometries on the fast-neutron depth-dose distributions was small. In the cylinder and slab the distributions were about 15% less than that calculated by Snyder and Neufeld for an infinite slab exposed to 2.5-MeV neutrons and were in agreement with depth-dose calculations of Auxier, Snyder and Jones for a 30-cm diameter cylinder exposed to 2.5-MeV neutrons. The associated gamma-dose distributions however were highly dependent on the choice of phantom size and shape. At depths greater than 20 cm in a 36-cm diameter cylinder the gamma-contribution became the largest component of the total dose. The depth distributions of the associated gamma-dose were compared with the epithermal neutron distributions indicated by the response of a Cd-covered gamma-detector. (Author).
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Category : Power resources
Languages : en
Pages : 1332
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Author: Azadeh Tasbaz
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Category :
Languages : en
Pages :
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Since the beginning of space exploration in last century, several kinds of devices from passive and active dosimeters to radiation environment monitors have been used to measure radiation levels onboard different space crafts and shuttles allowing the space community to identify and quantify space radiation. The recent construction of several laboratories on the International Space Station (ISS) has confirmed that prolonged duration space missions are now becoming standard practice and as such, the need to better understand the potential risk of space radiation to Astronaut?s health, has become a priority for long mission planner. The complex internal radiation environment created within the ISS is due to high-energy particle interactions within the ISS shielded environment. As a result, a large number of secondary particles, that pose specific health risks, are created. Neutrons are one important component of this mixed radiation field due to their high LET. Therefore, the assessment of the neutron dose contribution has become an important part of the safety and monitoring program onboard the ISS. The need to determine whether neutron dose measured externally to the human body give an accurate and conservative estimate of the dose received internally is of paramount importance for long term manned space missions. This thesis presents a part of an ongoing large research program on radiation monitoring on ISS called Matroshka-R Project that was established to analyze the radiation exposure levels onboard the ISS using different radiation instruments and a spherical phantom to simulate human body. Monte Carlo transport code was used to simulate the interaction of high energy protons and neutrons with the spherical phantom currently onboard ISS. A Monte Carlo model of the phantom has been built, and it consists of seven spherical layers presenting different depths of the simulated tissue. The phantom has been exposed to individual proton energies and to a spectrum of neutrons. The flux of the created neutrons inside the phantom has been calculated. The internal to external neutron flux ratio was calculated and compared to the experimental data, recently, measured on three separate expeditions of the ISS. The results from the calculations showed that the value of the neutron fluxes inside and outside the phantom is different from the data recently measured with bubble detectors.
Author:
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Category : Nuclear energy
Languages : en
Pages : 1288
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Author: International Atomic Energy Agency
Publisher: IAEA
ISBN:
Category : Business & Economics
Languages : en
Pages : 704
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This publication is aimed at students and teachers involved in teaching programmes in field of medical radiation physics, and it covers the basic medical physics knowledge required in the form of a syllabus for modern radiation oncology. The information will be useful to those preparing for professional certification exams in radiation oncology, medical physics, dosimetry or radiotherapy technology.
Author: H. Ing
Publisher:
ISBN:
Category : Neutrons
Languages : en
Pages : 368
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Author:
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ISBN:
Category : Nuclear energy
Languages : en
Pages : 960
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Author:
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ISBN:
Category : Power resources
Languages : en
Pages : 1144
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![Neutron Depth Dose from ([alpha], N) and ([gamma], N) Sources in a Tissue-equivalent Phantom PDF](https://books.google.com/books/content/images/frontcover/IaPxgAYpjr0C?fife=w80-h100)
Author: Henry Aceto (Jr.)
Publisher:
ISBN:
Category : Fast neutrons
Languages : en
Pages : 44
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