نتایج جستجو برای: air kerma strength

تعداد نتایج: 408460  

Journal: :Medical physics 2000
J F Williamson B M Coursey L A DeWerd W F Hanson R Nath M J Rivard G Ibbott

The National Institute of Standards and Technology (NIST) introduced a national standard for air kerma strength of the ThreaSeed Model 200 103Pd source (the only 103Pd seed available until 1999) in early 1999. Correct implementation of the NIST-99 standard requires the use of dose rate constants normalized to this same standard. Prior to the availability of this standard, the vendor's calibrati...

Journal: :The Review of scientific instruments 2014
J-E Groetz N Ounoughi C Mavon A Belafrites M Fromm

We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have be...

2015
Cristian Candela-Juan Facundo Ballester Jose Perez-Calatayud Javier Vijande

PURPOSE To provide a practical solution that can be adopted in clinical routine to fulfill the AAPM-ESTRO recommendations regarding quality assurance of seeds used in prostate permanent brachytherapy. The aim is to design a new insert for the well-ionization chamber SourceCheck(4π) 33005 (PTW, Germany) that allows evaluating the mean air-kerma strength of up to ten (125)I seeds with one single ...

2003
Stephen M. Seltzer Paul M. Bergstrom

Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from (60)Co, (137)Cs, and (192)Ir sources. The data developed for and from these calculations have also been used to refine a numbe...

Journal: :International journal of radiation oncology, biology, physics 2005
José Pérez-Calatayud Domingo Granero Facundo Ballester Vicente Puchades Emilio Casal Angela Soriano Vicente Crispín

PURPOSE To obtain the absolute dose-rate distribution in liquid water for all six cup-shaped Leipzig applicators by means of an experimentally validated Monte Carlo (MC) code. These six applicators were used in high-dose-rate (HDR) afterloaders with the "classic" and v2 (192)Ir sources. The applicators have an inner diameter of 1, 2, and 3 cm, with the source traveling parallel or perpendicular...

2004
Stephen M. Seltzer Paul J. Lamperti Robert Loevinger Michael G. Mitch James T. Weaver Bert M. Coursey

[This corrects the article on p. 337 in vol. 108.].

Journal: :Journal of radiological protection : official journal of the Society for Radiological Protection 2008
J A Cole D J Platten

Currently in the UK, shielding calculations for computed tomography (CT) systems are based on the BIR-IPEM (British Institute of Radiology and Institute of Physics in Engineering in Medicine) working group publication from 2000. Concerns have been raised internationally regarding the accuracy of the dose plots on which this method depends and the effect that new scanner technologies may have. A...

2015
Masahiro Hosoda Shinji Tokonami Yasutaka Omori Sarata Kumar Sahoo Suminori Akiba Atsuyuki Sorimachi Tetsuo Ishikawa Raghu Ram Nair Padmavathy Amma Jayalekshmi Paul Sebastian Kazuki Iwaoka Naofumi Akata Hiromi Kudo

A car-borne survey was carried out in Kerala, India to estimate external dose. Measurements were made with a 3-in × 3-in NaI(Tl) scintillation spectrometer from September 23 to 27, 2013. The routes were selected from 12 Panchayats in Karunagappally Taluk which were classified into high level, mid-level and low level high background radiation (HBR) areas. A heterogeneous distribution of air kerm...

2014
Tiago da Silva Jornada Teógenes Augusto da Silva

OBJECTIVE Aiming at contributing to the knowledge on doses in computed tomography (CT), this study has the objective of determining dosimetric quantities associated with pediatric abdominal CT scans, comparing the data with diagnostic reference levels (DRL). MATERIALS AND METHODS The study was developed with a Toshiba Asteion single-slice CT scanner and a GE BrightSpeed multi-slice CT unit in...

Journal: :Brazilian dental journal 2004
Andréa Gonçalves João Manuel Domingos de Almeida Rollo Marcelo Gonçalves Francisco Haiter Neto Frab Norberto Bóscolo

This study evaluated the performance of aluminum-copper alloy filtration, without the original aluminum filter, for dental radiography in terms of x-ray energy spectrum, air kerma rate and image quality. Comparisons of various thicknesses of aluminum-copper alloy in three different percentages were made with aluminum filtration. Tests were conducted on an intra-oral dental x-ray machine and wer...

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