Dosimetric evaluation of an epitaxial silicon diode as an online dosimeter for orthovoltage photon beam radiotherapy
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2021
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INTERNATIONAL SYMPOSIUM ON RADIATION PHYSICS, 15th
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The response of a dosimetry system based on an epitaxial silicon diode as an online
dosimeter for orthovoltage photon beam radiotherapy has been investigated in this work. To
be used as a dosimeter, each diode is housed in a light-tight probe, and its readout electrode is
directly connected to the Keithley 6517B electrometer. All current measurements are carried
out in short-circuit mode with the diode unbiased and its backplane grounded. The data
acquired by the electrometer are directly sent to a personal computer via a GBIP interface
controlled by software developed in LabView to analyze the current signals. A Pantak/Seifert
X-ray tube is used to irradiate the diode, placed 50.0 cm away in a radiation field of 8 cm,
with 10, 25, 30, and 50 kV photons. The dose rate response is investigated for the 50 kV
beam by varying the current tube from 2 to 20 mA. As expected, the induced current is
linearly dependent on the dose rate within the range of 0.8 and 8.05 mGy/s. The current
signals are quite stable, with a repeatability parameter of less than 0.2%. The dose-responses
assessed offline by integrating the current signals are linear between 0.5 and 3.0 Gy despite
being slightly dependent on the photon energy. However, in this dose range, no dose rate
dependence is observed. These results are theoretically supported by dose and dose rate
calculations performed assuming the diode is thin compared with the standard values of the
minority carrier diffusion lengths in the epitaxial layer. Good agreement is found between
calculations and experimental data. Investigations of possible radiation damage produced in
the diode through dynamic measurements of dark current and capacitance as a function of the
accumulated dose are currently in progress.
Como referenciar
BUENO, C.C.; GONCALVES, J.A.C.; MANGIAROTTI, A. Dosimetric evaluation of an epitaxial silicon diode as an online dosimeter for orthovoltage photon beam radiotherapy. In: INTERNATIONAL SYMPOSIUM ON RADIATION PHYSICS, 15th, December 6-10, 2021, Kuala Lumpur, Malaysia. Abstract... Disponível em: http://repositorio.ipen.br/handle/123456789/33682. Acesso em: 16 Mar 2025.
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.