Abstract
Purpose
The Bravos afterloader system was released by Varian Medical Systems in October of
2018 for high-dose-rate brachytherapy with 192Ir sources, containing new features such as the CamScale (a new device for daily quality
assurance and system recalibration), channel length verification, and different settings
for rigid and flexible applicators. This study mechanically evaluated the Bravos system
precision and accuracy for clinically relevant scenarios, using dummy sources.
Methods and Materials
The system was evaluated after three sets of experiments: (1) The CamScale was used to verify inter- and intra-channel dwelling variability and
system calibration; (2) A high-speed camera was used to verify the source simulation cable movement inside
a transparent quality assurance device, where dwell positions, dwell times, transit
times, speed profiles, and accelerations were measured; (3) The source movement inside clinical applicators was captured with an imaging panel
while being exposed to an external kV source. Measured and planned dwell positions
and times were compared.
Results
Maximum deviations between planned and measured dwell positions and times for the
source cable were 0.4 mm for the CamScale measurements and 0.07 seconds for the high-speed
camera measurements. Mean dwell position deviations inside clinical applicators were
below 1.2 mm for all applicators except the ring that required an offset correction
of 1 mm to achieve a mean deviation of 0.4 mm.
Conclusions
Features of the Bravos afterloader system provide a robust and precise treatment delivery.
All measurements were within manufacturer specifications.
Keywords
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References
- GammaMedplus™ iX instructions for use including the GammaMedplusTM 3/24 iX. Varian Medical Systems, Palo Alto, CA2018
- Bravos reference guide, version 1.0. Varian Medical Systems, Palo Alto, CA2018
- GammaMed, Plus, HDR, Carleton University Database. Version 2008-08-29.(Available at:)http://www.physics.carleton.ca/clrp/seed_database/Ir192_HDR/GammaMed_PlusDate accessed: January 15, 2019
- Dosimetry characteristics of the Plus and 12i Gammamed PDR 192Ir sources.Med Phys. 2001; 28: 2576-2585
- Comparative dosimetry of GammaMed Plus high-dose rate 192Ir brachytherapy source.J Med Phys. 2010; 35: 137-143
- Varisource afterloader features sheet. Varian Medical Systems, Palo Alto, CA2015
- Bravos instructions for use, version 1.0. Varian Medical Systems, Palo Alto, CA2018
- HDR 192Ir source speed measurements using a high speed video camera.Med Phys. 2015; 42: 412-415
- Varian brachytherapy applicators and accessories. Varian Medical Systems, Palo Alto, CA2011
- Technical note: Monte-Carlo dosimetry of the HDR 12i and Plus 192Ir sources.Med Phys. 2001; 28: 2586-2591
- Algorithm Reference Guide, version 1.0.Varian Medical systems, Palo Alto, CA2011
- Impact of source position on high-dose-rate skin surface applicator dosimetry.Brachytherapy. 2016; 15: 650-660
- A novel rectal applicator for contact radiotherapy with HDR 192Ir sources.Brachytherapy. 2018; 17: 1037-1044
- Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detector.Med Phys. 2010; 37: 5407-5411
- Comparison of the transit dose components and source kinematics of three high dose rate afterloading systems.Med Dosimetry. 1999; 24: 61-65
- The contribution from transit dose for 192Ir HDR brachytherapy treatments.Phys Med Biol. 2014; 59: 1831-1844
- Review of clinical brachytherapy uncertainties: Analysis guidelines of GEC-ESTRO and the AAPM.Radiother Oncol. 2014; 110: 199-212
- Dwell position inaccuracy in the Varian GammaMed HDR ring applicator.J Appl Clin Med Phys. 2010; 11: 291-296
- Direct reconstruction and associated uncertainties of 192Ir source dwell positions in ring applicators using gafchromic film in the treatment planning of HDR brachytherapy cervix patients.Phys Med Biol. 2013; 58: 3207-3225
- Determination of the accuracy of implant reconstruction and dose delivery in brachytherapy in The Netherlands and Belgium.Radiother Oncol. 2001; 59: 297-306
- A quality assurance tool for high-dose-rate brachytherapy.Med Phys. 2010; 37: 2525-2532
Article info
Publication history
Published online: July 18, 2019
Accepted:
June 20,
2019
Received in revised form:
June 12,
2019
Received:
April 17,
2019
Footnotes
Financial disclosure: There are no conflicts of interest to disclose. This study was funded and commissioned by Varian Medical Systems; however, the scope of work, experimental design, and reported results were formulated by the authors and not constrained by Varian.
Identification
Copyright
© 2019 Published by Elsevier Inc. on behalf of American Brachytherapy Society.
