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Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields

In‐vivo dosimetry techniques are currently being applied only by a few Centers because they require time‐consuming implementation measurements, and workload for detector positioning and data analysis. The transit in‐vivo dosimetry performed by the electronic portal imaging device (EPID) avoids the p...

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Autores principales: Cilla, Savino, Fidanzio, Andrea, Greco, Francesca, Sabatino, Domenico, Russo, Aniello, Gargiulo, Laura, Azario, Luigi, Piermattei, Angelo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718589/
https://www.ncbi.nlm.nih.gov/pubmed/21330974
http://dx.doi.org/10.1120/jacmp.v12i1.3279
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author Cilla, Savino
Fidanzio, Andrea
Greco, Francesca
Sabatino, Domenico
Russo, Aniello
Gargiulo, Laura
Azario, Luigi
Piermattei, Angelo
author_facet Cilla, Savino
Fidanzio, Andrea
Greco, Francesca
Sabatino, Domenico
Russo, Aniello
Gargiulo, Laura
Azario, Luigi
Piermattei, Angelo
author_sort Cilla, Savino
collection PubMed
description In‐vivo dosimetry techniques are currently being applied only by a few Centers because they require time‐consuming implementation measurements, and workload for detector positioning and data analysis. The transit in‐vivo dosimetry performed by the electronic portal imaging device (EPID) avoids the problem of solid‐state detector positioning on the patient. Moreover, the dosimetric characterization of the recent Elekta aSi EPIDs in terms of signal stability and linearity make these detectors useful for the transit in‐vivo dosimetry with 6, 10 and 15 MV photon beams. However, the implementation of the EPID transit dosimetry requires several measurements. Recently, the present authors have developed an in‐vivo dosimetry method for 3D CRT based on correlation functions defined by the ratios between the transit signal, [Formula: see text] , by the EPID and the phantom midplane dose, [Formula: see text] , at the source to axis distance (SAD) as a function of the phantom thickness, w, and the square field dimensions, L. When the phantom midplane was positioned at distance, d, from the SAD, the ratios [Formula: see text] were used to take into account the variation of the scattered photon contributions on the EPID as a function of d and L. The aim of this paper is the implementation of a procedure that uses generalized correlation functions obtained by nine Elekta Precise linac beams. The procedure can be used by other Elekta Precise linacs equipped with the same aSi EPIDs, assuming the stabilities of the beam output factors and the EPID signals. The procedure here reported avoids measurements in solid water equivalent phantoms needed to implement the in‐vivo dosimetry method in the radiotherapy department. A tolerance level ranging between [Formula: see text] and [Formula: see text] (depending on the type of tumor) was estimated for the comparison between the reconstructed isocenter dose, [Formula: see text] , and the computed dose, [Formula: see text] , by the treatment planning system (TPS). PACS number: 87.55.Qr; 87.56.Fc
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spelling pubmed-57185892018-04-02 Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields Cilla, Savino Fidanzio, Andrea Greco, Francesca Sabatino, Domenico Russo, Aniello Gargiulo, Laura Azario, Luigi Piermattei, Angelo J Appl Clin Med Phys Radiation Measurements In‐vivo dosimetry techniques are currently being applied only by a few Centers because they require time‐consuming implementation measurements, and workload for detector positioning and data analysis. The transit in‐vivo dosimetry performed by the electronic portal imaging device (EPID) avoids the problem of solid‐state detector positioning on the patient. Moreover, the dosimetric characterization of the recent Elekta aSi EPIDs in terms of signal stability and linearity make these detectors useful for the transit in‐vivo dosimetry with 6, 10 and 15 MV photon beams. However, the implementation of the EPID transit dosimetry requires several measurements. Recently, the present authors have developed an in‐vivo dosimetry method for 3D CRT based on correlation functions defined by the ratios between the transit signal, [Formula: see text] , by the EPID and the phantom midplane dose, [Formula: see text] , at the source to axis distance (SAD) as a function of the phantom thickness, w, and the square field dimensions, L. When the phantom midplane was positioned at distance, d, from the SAD, the ratios [Formula: see text] were used to take into account the variation of the scattered photon contributions on the EPID as a function of d and L. The aim of this paper is the implementation of a procedure that uses generalized correlation functions obtained by nine Elekta Precise linac beams. The procedure can be used by other Elekta Precise linacs equipped with the same aSi EPIDs, assuming the stabilities of the beam output factors and the EPID signals. The procedure here reported avoids measurements in solid water equivalent phantoms needed to implement the in‐vivo dosimetry method in the radiotherapy department. A tolerance level ranging between [Formula: see text] and [Formula: see text] (depending on the type of tumor) was estimated for the comparison between the reconstructed isocenter dose, [Formula: see text] , and the computed dose, [Formula: see text] , by the treatment planning system (TPS). PACS number: 87.55.Qr; 87.56.Fc John Wiley and Sons Inc. 2010-10-27 /pmc/articles/PMC5718589/ /pubmed/21330974 http://dx.doi.org/10.1120/jacmp.v12i1.3279 Text en © 2011 The Authors. This is an open access article under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/3.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Radiation Measurements
Cilla, Savino
Fidanzio, Andrea
Greco, Francesca
Sabatino, Domenico
Russo, Aniello
Gargiulo, Laura
Azario, Luigi
Piermattei, Angelo
Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields
title Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields
title_full Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields
title_fullStr Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields
title_full_unstemmed Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields
title_short Correlation functions for Elekta aSi EPIDs used as transit dosimeter for open fields
title_sort correlation functions for elekta asi epids used as transit dosimeter for open fields
topic Radiation Measurements
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718589/
https://www.ncbi.nlm.nih.gov/pubmed/21330974
http://dx.doi.org/10.1120/jacmp.v12i1.3279
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