New LMRI-CIEMAT primary standard for 137Cs air-kerma

The results of development of the national primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2011 in 2019 are presented according to the recommendations of the ICRU Report No. 90 “Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications”. The following changes are made to the equations for the units determination with the standard: in the field of X-rays, new correction coefficients of the free-air ionization chambers are introduced and the relative standard uncertainty of the average energy to create an ion pair in air is changed; in the field of gamma radiation, the product of the average energy to create an ion pair in air and the electron stopping-power graphite to air ratio for the cavity ionization chambers is changed. More accurate values of the units reproduced by GET 8-2019 are obtained and new metrological characteristics of the standard are stated.

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GET 8–2019 State Primary Standard of Units of Air Kerma, Air Kerma Rate, Exposure, Exposure Rate, and Energy Flux of X-Radiation and Gamma Radiation

Measurement Techniques ◽

10.1007/s11018-020-01828-7 ◽

2020 ◽

Vol 63 (8) ◽

pp. 597-601

Author(s):

A. V. Oborin ◽

A. Yu. Villevalde ◽

S. G. Trofimchuk

Keyword(s):

Gamma Radiation ◽

Energy Flux ◽

Primary Standard ◽

State Primary Standard ◽

Exposure Rate ◽

Air Kerma ◽

Air Kerma Rate

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RE-EVALUATION OF THE AIR KERMA PRIMARY STANDARD OF THE SMU IN 60Co AND 137Cs GAMMA RAY BEAMS

Radiation Protection Dosimetry ◽

10.1093/rpd/ncz210 ◽

2019 ◽

Vol 186 (2-3) ◽

pp. 235-238

Author(s):

Norman Durný

Keyword(s):

Gamma Ray ◽

Primary Standard ◽

National Standard ◽

Key Comparisons ◽

Main Role ◽

Correction Factors ◽

Active Volume ◽

Air Kerma ◽

60Co Gamma

Abstract The primary standard for air kerma of the Slovak Institute of Metrology (SMU) as a part of national standard of dosimetric quantities of gamma radiation NE028/02, based on cylindrical graphite walled cavity ionization chamber was established in 2002 for the 60Co gamma ray beams. Since then the main role of SMU was to continuously maintain, develop and refurbish the standard with related accessory to ensure international equivalence. Since 2002, a re-evaluation of the active volume of the ionizing chamber, correction factors, the key data, due to adoption of ICRU Report 90(1), and changes of the calibrations methods and corrections of the equipment were made to obtain improved parameters. The range was extended for 137Cs gamma ray beams and key comparisons with the Bureau International des Poids et Mesures (BIPM) were performed. ICRU Report 90(1) implementation led to a decrease of the Gray of −0.84% for 60Co and −0.80% for 137Cs.

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Direct calibration of a reference standard against the air kerma strength primary standard, at192Ir HDR energy

Physics in Medicine and Biology ◽

10.1088/0031-9155/47/7/304 ◽

2002 ◽

Vol 47 (7) ◽

pp. 1047-1058 ◽

Cited By ~ 6

Author(s):

K N Govinda Rajan ◽

T Palani Selvam ◽

B C Bhatt ◽

M Vijayam ◽

V S Patki ◽

...

Keyword(s):

Primary Standard ◽

Reference Standard ◽

Air Kerma

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New LNHB primary standard for60Co air kerma

Metrologia ◽

10.1088/0026-1394/47/6/004 ◽

2010 ◽

Vol 47 (6) ◽

pp. 652-658 ◽

Cited By ~ 3

Author(s):

F Delaunay ◽

M Donois ◽

J Gouriou ◽

E Leroy ◽

A Ostrowsky

Keyword(s):

Primary Standard ◽

Air Kerma

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Revised correction factor for the UK national primary standard for air kerma for137Cs and60Co gamma-rays

Metrologia ◽

10.1088/0026-1394/46/5/n03 ◽

2009 ◽

Vol 46 (5) ◽

pp. L26-L26 ◽

Cited By ~ 1

Author(s):

Julia Pearce ◽

Graham Bass ◽

Simon Duane ◽

Rebecca Nutbrown ◽

David Shipley

Keyword(s):

Correction Factor ◽

Gamma Rays ◽

Primary Standard ◽

National Primary Standard ◽

Air Kerma ◽

The Uk

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Recombination Parameters of some Fabricated Ionization Chambers

Bangladesh Journal of Medical Physics ◽

10.3329/bjmp.v4i1.14694 ◽

2013 ◽

Vol 4 (1) ◽

pp. 101-106

Author(s):

Afia Begum ◽

Nobuhisa Takata

Keyword(s):

Ionization Chamber ◽

Medical Physics ◽

Primary Standard ◽

Ionization Chambers ◽

Spherical Type ◽

Air Kerma ◽

Parameter Values ◽

Recombination Parameter ◽

Industrial Science

Some pancake and spherical type ionization chambers of various size have been designed and fabricated for absolute air kerma measurement in 60Co and 137Cs ?-ray fields at the Primary Standard Dosimetry Laboratory (PSDL), National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Japan. Values of recombination parameters A and m2g of these ionization chambers are obtained using a method proposed by De Almeida and Niatel and adopted by Boutillon. For absolute air kerma measurement, it is important to obtain accurate signal currents by correcting it for ion losses using the values of A and m2g of each of the ionization chambers. It has been observed from the measurements that the recombination parameters for pancake ionization chamber are smaller than spherical ionization chambers and for spherical type ionization chamber recombination parameter values depend on the dimensions of the electrodes and also the size of the chambers. DOI: http://dx.doi.org/10.3329/bjmp.v4i1.14694 Bangladesh Journal of Medical Physics Vol.4 No.1 2011 101-106

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Evaluation of Wall Correction Factor of INER's Air-Kerma Primary Standard Chamber and Dose Variation by Source Displacement for HDR192Ir Brachytherapy

BioMed Research International ◽

10.1155/2013/436979 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8

Author(s):

J. H. Lee ◽

J. N. Wang ◽

T. T. Huang ◽

S. H. Su ◽

B. J. Chang ◽

...

Keyword(s):

Monte Carlo ◽

Monte Carlo Method ◽

Treatment Plan ◽

Primary Standard ◽

National Physical Laboratory ◽

High Dose Rate ◽

High Dose ◽

Air Kerma ◽

The Monte Carlo Method ◽

Wall Correction Factor

The aim of the present study was to estimate the wall effect of the self-made spherical graphite-walled cavity chamber with the Monte Carlo method for establishing the air-kerma primary standard of high-dose-rate (HDR)192Ir brachytherapy sources at the Institute of Nuclear Energy Research (INER, Taiwan). The Monte Carlo method established in this paper was also employed to respectively simulate wall correction factors of the192Ir air-kerma standard chambers used at the National Institute of Standards and Technology (NIST, USA) and the National Physical Laboratory (NPL, UK) for comparisons and verification. The chamber wall correction calculation results will be incorporated into INER's HDR192Ir primary standard in the future. For the brachytherapy treatment in the esophagus or in the bronchi, the position of the isotope may have displacement in the cavity. Thus the delivered dose would differ from the prescribed dose in the treatment plan. We also tried assessing dose distribution due to the position displacement of HDR192Ir brachytherapy source in a phantom with a central cavity by the Monte Carlo method. The calculated results could offer a clinical reference for the brachytherapy within the human organs with cavity.

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