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| DOI | 10.1002/MP.13920 | ||||
| Año | 2020 | ||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
Purpose To evaluate the use of the absorbed depth-dose as a surrogate of the half-value layer in the calibration of a high-dose-rate electronic brachytherapy (eBT) equipment. The effect of the manufacturing tolerances and the absorbed depth-dose measurement uncertainties in the calibration process are also addressed. Methods The eBT system Esteya (R) (Elekta Brachytherapy, Veenendaal, The Netherlands) has been chosen as a proof-of-concept to illustrate the feasibility of the proposed method, using its 10 mm diameter applicator. Two calibration protocols recommended by the AAPM (TG-61) and the IAEA (TRS-398) for low-energy photon beams were evaluated. The required Monte Carlo (MC) simulations were carried out using PENELOPE2014. Several MC simulations were performed modifying the flattening filter thickness and the x-ray tube potential, generating one absorbed depth-dose curve and a complete set of parameters required in the beam calibration (i.e., HVL, backscatter factor (B-w), and mass energy-absorption coefficient ratios (mu(en)/rho)(water,air)), for each configuration. Fits between each parameter and some absorbed dose-ratios calculated from the absorbed depth-dose curves were established. The effect of the manufacturing tolerances and the absorbed dose-ratio uncertainties over the calibration process were evaluated by propagating their values over the fitting function, comparing the overall calibration uncertainties against reference values. We proposed four scenarios of uncertainty (from 0% to 10%) in the dose-ratio determination to evaluate its effect in the calibration process. Results The manufacturing tolerance of the flattening filter (+/- 0.035 mm) produces a change of 1.4% in the calculated HVL and a negligible effect over the B-w, (mu(en)/rho)(water,air), and the overall calibration uncertainty. A potential variation of 14% of the electron energies due to manufacturing tolerances in the x-ray tube (69.5 +/- similar to 10 keV) generates a variation of 10% in the HVL. However, this change has a negligible effect over the B-w and (mu(en)/rho)(water,air), adding 0.1% to the overall calibration uncertainty. The fitting functions reproduce the data with an uncertainty (k = 2) below 1%, 0.5%, and 0.4% for the HVL, B-w, and (mu(en)/rho)(water,air), respectively. The four studied absorbed dose-ratio uncertainty scenarios add, in the worst-case scenario, 0.2% to the overall uncertainty of the calibration process. Conclusions This work shows the feasibility of using the absorbed depth-dose curve in the calibration of an eBT system with minimal loss of precision.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| 1 | VALDES-CORTEZ, CHRISTIAN NELSON | Hombre |
Univ Valencia - España
Ctr Oncol Norte - Chile University of Valencia - España Centro Oncológico del Norte - Chile Universitat de València - España |
| 2 | Niatsetski, Yury | Hombre |
R&D Elekta Brachytherapy - Países Bajos
Elekta Brachytherapy - Países Bajos |
| 3 | Ballester, Facundo | Hombre |
Univ Valencia - España
IIS La Fe UV - España University of Valencia - España Instituto de Investigación Sanitaria La Fe - España Universitat de València - España |
| 4 | Vijande, Javier | Hombre |
Univ Valencia - España
IIS La Fe UV - España University of Valencia - España Instituto de Investigación Sanitaria La Fe - España Universitat de València - España |
| 5 | Candela-Juan, Cristian | Hombre |
Inst Nacl Gest Sanitaria - España
Instituto Nacional de Gestión Sanitaria - España |
| 6 | Perez-Calatayud, Jose | Hombre |
IIS La Fe UV - España
La Fe Hosp - España Instituto de Investigación Sanitaria La Fe - España Hospital Universitari i Politècnic La Fe - España |
| Fuente |
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| European Regional Development Fund |
| Generalitat Valenciana |
| Ministerio de Economía, Industria y Competitividad, Gobierno de España |
| EU FEDER |
| Ministerio de Economia, Industria y Competitividad (Spain) |
| Ministerio de Asuntos Económicos y Transformación Digital, Gobierno de España |
| Agradecimiento |
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| This work has been partially funded by Ministerio de Economia, Industria y Competitividad (Spain) and EU FEDER under Contract PGC2018-101302, and by Generalitat Valenciana through the project AICO/2019/132. |
| This work has been partially funded by Ministerio de Economía, Industria y Competitividad (Spain) and EU FEDER under Contract PGC2018‐101302, and by Generalitat Valenciana through the project AICO/2019/132. |