Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with 192 Ir

Autor: Eduardo José Fernández Rodríguez, María Ferri, Manuel Fernández‐Montes, Damián Guirado, María T. Pacheco, Ana M. Tornero-López, Javier Anchuelo, Rosa Fabregat‐Borrás, Juan Cardenal, Mercedes Pérez‐Macho, Ana Domínguez García, Pedro J. Prada, S. Ruiz-Arrebola
Rok vydání: 2020
Předmět:
Zdroj: Medical Physics. 47:2242-2253
ISSN: 2473-4209
0094-2405
Popis: PURPOSE The objective of this study was to characterize the Best Medical Canada microMOSFET detectors for their application in in vivo dosimetry for high-dose-rate brachytherapy (HDRBT) with 192 Ir. We also developed a mathematical model to correct dependencies under the measurement conditions of these detectors. METHODS We analyzed the linearity, reproducibility, and interdetector variability and studied the microMOSFET response dependence on temperature, source-detector distance, and angular orientation of the receptor with respect to the source. The correction model was applied to 19 measurements corresponding to five simulated treatments in a custom phantom specifically designed for this purpose. RESULTS The detectors (high bias applied in all measurements) showed excellent linearity up to 160 Gy. The response dependence on source-detector distance varied by (8.65 ± 0.06)% (k = 1) for distances between 1 and 7 cm, and the variation with temperature was (2.24 ± 0.05)% (k = 1) between 294 and 310 K. The response difference due to angular dependence can reach (10.3 ± 1.3)% (k = 1). For the set of measurements analyzed, regarding angular dependences, the mean difference between administered and measured doses was -4.17% (standard deviation of 3.4%); after application of the proposed correction model, the mean difference was -0.1% (standard deviation of 2.2%). For the treatments analyzed, the average difference between calculations and measures was 4.7% when only the calibration coefficient was used, but it is reduced to 0.9% when the correction model is applied. CONCLUSION Important response dependencies of microMOSFET detectors used for in vivo dosimetry in HDRBT treatments, especially the angular dependence, can be adequately characterized by a correction model that increases the accuracy of this system in clinical applications.
Databáze: OpenAIRE
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