Angular dependence of an intercomparison system in low and medium energies of X-rays beams
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2004
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INTERNATIONAL CONGRESS OF THE INTERNATIONAL RADIATION PROTECTION ASSOCIATION, 11th
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Resumo
Ionization chambers are radiation detectors widely used for Xrays measurements and quality control tests in diagnostic radiology. In radiotherapy, the
ionization chambers are used for determining the absorbed dose delivered to the patient.
An ionization chamber can take many forms, but the principle of operation is similar for
all chambers. It is based on the collection of charges created by the passage of radiation,
with a proper voltage maintained between the wall of the chamber and the central
electrode. In this work, the dependence of detector response on angle of incident
radiation was evaluated for three ionization chambers used as an intercomparison
standard system in low and medium x-ray beams. The ionization chambers tested are
Victoreen guarded electrode with an approximately air equivalent wall, models 415,
415A and 415B. The guarded electrode construction permits direct current measurement
with a minimum amount of drift. The irradiations were carried out using two different
systems: a) Rigaku Denki generator, model Geigerflex, with a Philips tube model
PW/2184/00 (tungsten target and beryllium window, 60 kV), and b) Pantak model HF
320 (tungsten target and beryllium window, 320 kV). All measurements were carried
out in reference conditions. The variation of the response for the chamber model 415A,
was verified in function of the plane of the entrance window tilted by ±5° from its
reference position, perpendicular to the axis of the radiation beam, according to
international recommendations. The tests were performed measuring the chamber
response, at tilt angles of 1° apart. For models 415 and 415B respectively, the chambers
were rotated around their central axis from – 180° to +180° in steps of 30°. The
responses of the chambers were normalized to the reference position (0°), and the
results obtained meet the international recommendations, i.e., the limits of variation of
response are within ±1.0%.
Como referenciar
ROCHA, F.D.G.; ALVAREZ, O.T.B.; CALDAS, L.V.E. Angular dependence of an intercomparison system in low and medium energies of X-rays beams. In: INTERNATIONAL CONGRESS OF THE INTERNATIONAL RADIATION PROTECTION ASSOCIATION, 11th, 23-28 May, 2004, Madrid, Spain. Disponível em: http://repositorio.ipen.br/handle/123456789/19910. Acesso em: 27 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.