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Rahimi, S A, Hashemi, B, Mahdavi, S R. (1397). Estimation of Dosimetric Parameters based on KNR and KNCSF Correction Factors for Small Field Radiation Therapy at 6 and 18 MV Linac Energies using Monte Carlo Simulation Methods. سامانه مدیریت نشریات علمی, 9(1), 37-50. doi: 10.31661/jbpe.v9i1Feb.414
S A Rahimi; B Hashemi; S R Mahdavi. "Estimation of Dosimetric Parameters based on KNR and KNCSF Correction Factors for Small Field Radiation Therapy at 6 and 18 MV Linac Energies using Monte Carlo Simulation Methods". سامانه مدیریت نشریات علمی, 9, 1, 1397, 37-50. doi: 10.31661/jbpe.v9i1Feb.414
Rahimi, S A, Hashemi, B, Mahdavi, S R. (1397). 'Estimation of Dosimetric Parameters based on KNR and KNCSF Correction Factors for Small Field Radiation Therapy at 6 and 18 MV Linac Energies using Monte Carlo Simulation Methods', سامانه مدیریت نشریات علمی, 9(1), pp. 37-50. doi: 10.31661/jbpe.v9i1Feb.414
Rahimi, S A, Hashemi, B, Mahdavi, S R. Estimation of Dosimetric Parameters based on KNR and KNCSF Correction Factors for Small Field Radiation Therapy at 6 and 18 MV Linac Energies using Monte Carlo Simulation Methods. سامانه مدیریت نشریات علمی, 1397; 9(1): 37-50. doi: 10.31661/jbpe.v9i1Feb.414

Estimation of Dosimetric Parameters based on KNR and KNCSF Correction Factors for Small Field Radiation Therapy at 6 and 18 MV Linac Energies using Monte Carlo Simulation Methods

Journal of Biomedical Physics and Engineering
مقاله 5، دوره 9، شماره 1، فروردین و اردیبهشت 2019، صفحه 37-50    اصل مقاله (902.41 K)
نوع مقاله: Original Research
شناسه دیجیتال (DOI): 10.31661/jbpe.v9i1Feb.414
نویسندگان
S A Rahimi1، 2؛ B Hashemi* 3؛ S R Mahdavi4
1PhD Candidate, Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
2Assistant Professor, Department of Basic Sciences, Faculty of Health Sciences, Mazandaran University of Medical Sciences, Sari, Iran
3Associate Professor, Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
4Associate Professor, Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
چکیده
Background: Estimating dosimetric parameters for small fields under non-reference conditions leads to significant errors if done based on conventional protocols used for large fields in reference conditions. Hence, further correction factors have been introduced to take into account the influence of spectral quality changes when various detectors are used in non-reference conditions at different depths and field sizes.
Objective: Determining correction factors (KNR and KNCSF) recommended recently for small field dosimetry formalism by American Association of Physicists in Medicine (AAPM) for different detectors at 6 and 18 MV photon beams.
Methods: EGSnrc Monte Carlo code was used to calculate the doses measured with different detectors located in a slab phantom and the recommended KNR and KNCSF correction factors for various circular small field sizes ranging from 5-30 mm diameters. KNR and KNCSF correction factors were determined for different active detectors (a pinpoint chamber, EDP-20 and EDP-10 diodes) in a homogeneous phantom irradiated to 6 and 18 MV photon beams of a Varian linac (2100C/D).
Results: KNR correction factor estimated for the highest small circular field size of 30 mm diameter for the pinpoint chamber, EDP-20 and EDP-10 diodes were 0.993, 1.020 and 1.054; and 0.992, 1.054 and 1.005 for the 6 and 18 MV beams, respectively. The KNCSF correction factor estimated for the lowest circular field size of 5 mm for the pinpoint chamber, EDP-20 and EDP-10 diodes were 0.994, 1.023, and 1.040; and 1.000, 1.014, and 1.022 for the 6 and 18 MV photon beams, respectively.
Conclusion: Comparing the results obtained for the detectors used in this study reveals that the unshielded diodes (EDP-20 and EDP-10) can confidently be recommended for small field dosimetry as their correction factors (KNR and KNCSF) was close to 1.0 for all small field sizes investigated and are mainly independent from the electron beam spot size.
کلیدواژه‌ها
Small field radiotherapy؛ Correction factors؛ TG155؛ Monte Carlo؛ Pinpoint chamber؛ Diode dosimeter
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