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Title: SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting

Abstract

Purpose: In commissioning of volumetric modulated arc therapy (VMAT), it is necessary to evaluate the beam characteristics of various dose rate settings with potential to use. The aim of this study is to evaluate the beam characteristics of flattened and flattening filter free (FFF) including low dose rate setting. Methods: We used a Varian TrueBeam with Millennium 120 MLC. Both 6 and 10 MV beams with or without flattening filter were used for this study. To evaluate low-dose rate FFF beams, specially-designed leaf sequence files control out-of-field MLC leaf pair at constant dose rate ranging from 80 to 400 MU/min. For dose rate from 80 MU/min to the maximum usable value of all energies, beam output were measured using ionization chamber (CC04, IBA). The ionization chamber was inserted into water equivalent phantom (RT3000-New, R-tech), and the phantom was set with SAD of 100cm. The beam profiles were performed using the 2D diode array (Profiler2, Sun Nuclear). The SSD was set to 90cm and a combined 30cmx30cmx9cm phantom which consisted of solid water slabs was put on the device. All measurement were made using 100MU irradiation for 10cmx10cm jaw-defined field size with a gantry angle of 0°. Results: In all energies,more » the dose rate dependences with beam output and variation coefficient were within 0.2% and 0.07%, respectively. The flatness and symmetry exhibited small variations (flatness ≤0.1 point and symmetry≤0.3 point at absolute difference). Conclusion: We had studied the characteristics of flattened and FFF beam over the 80 MU/min. Our results indicated that the beam output and profiles of FFF of TrueBeam linac were highly stable at low dose rate setting.« less

Authors:
; ; ; ; ;  [1]; ; ;  [2]
  1. Kobe Minimally Invasive Cancer Center, Kobe, Hyogo (Japan)
  2. Kobe University Hospital, Kobe, Hyogo (Japan)
Publication Date:
OSTI Identifier:
22545270
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; BEAM PRODUCTION; BEAM PROFILES; BEAMS; COMMISSIONING; DOSE RATES; IONIZATION CHAMBERS; IRRADIATION; PHANTOMS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Uehara, K, Ogata, T, Nakayama, M, Shinji, T, Nishimura, H, Masutani, T, Ishihara, T, Ejima, Y, and Sasaki, R. SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting. United States: N. p., 2015. Web. doi:10.1118/1.4924507.
Uehara, K, Ogata, T, Nakayama, M, Shinji, T, Nishimura, H, Masutani, T, Ishihara, T, Ejima, Y, & Sasaki, R. SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting. United States. https://doi.org/10.1118/1.4924507
Uehara, K, Ogata, T, Nakayama, M, Shinji, T, Nishimura, H, Masutani, T, Ishihara, T, Ejima, Y, and Sasaki, R. 2015. "SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting". United States. https://doi.org/10.1118/1.4924507.
@article{osti_22545270,
title = {SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting},
author = {Uehara, K and Ogata, T and Nakayama, M and Shinji, T and Nishimura, H and Masutani, T and Ishihara, T and Ejima, Y and Sasaki, R},
abstractNote = {Purpose: In commissioning of volumetric modulated arc therapy (VMAT), it is necessary to evaluate the beam characteristics of various dose rate settings with potential to use. The aim of this study is to evaluate the beam characteristics of flattened and flattening filter free (FFF) including low dose rate setting. Methods: We used a Varian TrueBeam with Millennium 120 MLC. Both 6 and 10 MV beams with or without flattening filter were used for this study. To evaluate low-dose rate FFF beams, specially-designed leaf sequence files control out-of-field MLC leaf pair at constant dose rate ranging from 80 to 400 MU/min. For dose rate from 80 MU/min to the maximum usable value of all energies, beam output were measured using ionization chamber (CC04, IBA). The ionization chamber was inserted into water equivalent phantom (RT3000-New, R-tech), and the phantom was set with SAD of 100cm. The beam profiles were performed using the 2D diode array (Profiler2, Sun Nuclear). The SSD was set to 90cm and a combined 30cmx30cmx9cm phantom which consisted of solid water slabs was put on the device. All measurement were made using 100MU irradiation for 10cmx10cm jaw-defined field size with a gantry angle of 0°. Results: In all energies, the dose rate dependences with beam output and variation coefficient were within 0.2% and 0.07%, respectively. The flatness and symmetry exhibited small variations (flatness ≤0.1 point and symmetry≤0.3 point at absolute difference). Conclusion: We had studied the characteristics of flattened and FFF beam over the 80 MU/min. Our results indicated that the beam output and profiles of FFF of TrueBeam linac were highly stable at low dose rate setting.},
doi = {10.1118/1.4924507},
url = {https://www.osti.gov/biblio/22545270}, journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}