Analysis of the correction factor for the effect of the volumetric average using thermoluminescent dosimeters
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2024
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INTERNATIONAL SYMPOSIA ON RADIATION PHYSICS, 19th
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Resumo
Among the dosimetry complexities of making use of small fields, the volume average correction
factor is an essential factor for analysis. This factor is defined as the ratio between the dose absorbed in
water at the reference point of the water phantom in the absence of the detector and the average dose
absorbed over the sensitive volume of the detector (still in the absence of the detector). This occurs
because the detector has a significant volume, having the potential to influence dosimetry depending on
the region that has a high dose gradient or the size of the field that is intended to be measured (1,2,3).
The objective of this work was to analyze the volumetric mean factor using TLDs (LiF:Mg,Ti; µLiF:Mg,Ti;
CaSO4:Dy). To develop the effect of the volumetric average, some parameters are necessary, such as: the
dimensions of the dosimeters and the profiles of the radiation beam. Due to the geometry of the
dosimeters or detector used, it is necessary to take into account the weight function, w(x,y)(2). This
parameter should approximate the dosimeter to a detector shape, such as: line, cylinder, cylinder with
central electrode or a circular shape. In this work, the dosimeters were approximated to a detector with a
circular shape like the diode, due to the face of the dosimeter facing the central beam of the linear
accelerator. To be used the beam profiles were approximated to a Gaussian distribution that was obtained
by the graphics program origin, in version 9.0. To calculate the volumetric average, a code developed by
Cunha, 2019 using the Scilab software, version 6.0, was used. The fields analyzed were 2 x2 cm2
; 1 x 1 cm2 and 0,5 x 0,5 cm2. The results obtained demonstrated that the µLiF was the dosimeter that had the
least influence on the fields, showing an influence of only 2% in the 0.5 x 0.5 cm2
field, being considered the best detector for small field dosimetry. The LiF:Mg,Ti dosimeter showed a significant influence of
8% in the 1 x 1 cm2 field. CaSO4:Dy had an influence of 60% and is not recommended for use in fields smaller than 1 x 1 cm2.
Como referenciar
ALMEIDA, S.B.; CUNHA, A. P. V.; SAMPAIO, C. C.; CAMPOS, L.L. Analysis of the correction factor for the effect of the volumetric average using thermoluminescent dosimeters. In: PESSANHA, SOFIA (ed.); MANSO, MARTA (ed.). In: INTERNATIONAL SYMPOSIA ON RADIATION PHYSICS, 19th, September 1-5, 2024, Lisbon, Portugal. Abstract... Lisbon: Universidade Nova de Lisboa - Faculdade de Ciências e Tecnologia, Lisboa, 2024. p. 49-49. Disponível em: https://repositorio.ipen.br/handle/123456789/48965. Acesso em: 30 Dec 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.