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

Autor: Ruiz-Arrebola S; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Fabregat-Borrás R; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Rodríguez E; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Fernández-Montes M; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Pérez-Macho M; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Ferri M; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., García A; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Cardenal J; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Pacheco MT; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Anchuelo J; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Tornero-López AM; Servicio de Radiofísica y Protección Radiológica, Hospital Universitario Dr. Negrín, Gran Canaria, Spain., Prada PJ; Marqués de Valdecilla University Hospital, Department of Radiation Oncology and Radiophysics, Santander, Spain., Guirado D; Instituto de Investigación Biosanitaria (ibs.GRANADA), Hospital Clínico Universitario San Cecilio, Unidad de Radiofísica, Granada, Spain.; CIBER de Epidemiología y Salud Pública (CIBERESP), Granada, Spain.
Jazyk: angličtina
Zdroj: Medical physics [Med Phys] 2020 Jun; Vol. 47 (5), pp. 2242-2253. Date of Electronic Publication: 2020 Mar 18.
DOI: 10.1002/mp.14080
Abstrakt: 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.
(© 2020 American Association of Physicists in Medicine.)
Databáze: MEDLINE
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