Dosimetric evaluation of Gafchromic EBT2 film for breast intraoperative electron radiotherapy verification

Background: Before treatment planning and dose delivery, quality assurance of multi-leaf collimator (MLC) has an important role in intensity-modulated radiation therapy (IMRT) due to the creation of multiple segments from optimization process.Objective: The purpose of this study is to assess the quality control of MLC leaves using EBT3 Gafchromic films.Material and Methods: Leaf Position accuracy and leaf gap reproducibility were checked with Garden fence test. The garden fence test consists of 5 thin bands A) 0.2 Cm width spaced at 2 Cm intervals and B) 1 Cm width spaced at 1 Cm intervals. Each leaf accuracy was analyzed with measuring the full-width half-maximum (FWHM). Maximum and average leaf transmission were measured with gafchromic EBT3 films from Ashland for both 6 MV and 18 MV beams.Results: Leaf positions were found to be in a range between 1.78 – 2.53 mm, instead of nominal 2 mm for the test A and between 9.09 – 10.36 mm, instead of nominal 10 mm for the test B. The Average radiation transmission of the MLC was noted 1.79% and 1.98% of the open 10x10 Cm2 field at isocenter for 6 MV and 18 MV beams, respectively. Maximum radiation transmission was noted 4.1% and 4.4% for 6 MV and 18 MV beams, respectively.Conclusion: In this study, application of gafchromic EBT3 films for the quality assurance of Euromechanics multileaf collimator was studied. Our results showed that the average leaf leakage and positional accuracy of this type of MLC were in the acceptance level based on the Protocols.

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“…Net optical densities (Net OD) and the standard deviations (σ) were determined according to the equations (1-2) [12,20,21]:…”

Section: Methodsmentioning

confidence: 99%

Physical and Dosimetric Aspect of Euromechanics Add-on Multileaf Collimator on Varian Clinac 2100 C/D

et al. 2019

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“…2B and analyzed at the red and green channels using the ImageJ program (image J, 64 bit 1.6.0 version; National Institutes of Health, Bethesda, MD, USA). To calculate the standard deviation of fitting coefficient, OriginPro software (Originlab Corporation, Northampton, MA, USA) was used 1) and the dose calibration curves were calculated.…”

Section: Dose Profile Measurement By Ebt3 and Ebt-xd Filmsmentioning

confidence: 99%

Validation of Gamma Knife Perfexion Dose Profile Distribution by a Modified Variable Ellipsoid Modeling Technique

Hur

Jin

Kim

et al. 2021

J Korean Neurosurg Soc

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“…Due to the both energy and dose rate independent response of EBT2 film [15], employed films were calibrated by 9 MeV electron beam of a Varian 2100C/D external radiotherapy accelerator and its dose-response curve was extracted at the red channel [24].…”

Section: Film Dosimetrymentioning

confidence: 99%

“…One of the other important issues in IOERT is the lack of an imagebased treatment planning procedure [15]. Treatment planning calculations in IOERT is mainly based on the acquired percentage depth doses (PDDs) along the clinical axis of employed applicators at different energies.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the performance characteristics of some ion chamber dosimeters in high dose per pulse intraoperative electron beam radiation therapy

et al. 2019

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Introduction: Employing routine dosimetry protocols for intraoperative electron beam needs further refinements to obtain reliable results. In this regard, the performance of some cylindrical and parallel plate ion chambers for both relative and absolute dosimetry of intraoperative electron beam has been evaluated. Materials and methods: Four different ion chambers including Semiflex and PinPoint cylindrical chambers as well as Advanced Markus and Roos parallel plate ones were employed for PDD measurement and dose rate determination in reference condition of the electron beam produced by LIAC intraoperative accelerator. The results of PDD measurements were compared with those of Gafchromic EBT2 film. Specific recommendations were followed to determine the chamber correction factors including k s and k Q,Q0 for absolute dosimetry in intraoperative reference condition. Results: There was good agreement between PDDs measured by employed chambers and EBT2 film at all nominal energies. Nevertheless, Advanced Markus chamber had the best performance based on the gamma analysis results. Obtained k Q,Q0 and k s for studied ion chambers largely differed from expected values by TRS-398 protocol. The difference of measured dose rates at 12 MeV energy by investigated chambers was less than 1.1% and Advanced Markus had the best accordance with pre-set dose rate by manufacture. Conclusion: Results showed that ignoring the specific recommended procedures in determining the chamber correction factors causes the overestimation of the measured dose. Therefore, dedicated dosimetry protocol should be developed for high dose per pulse intraoperative electron dosimetry including all of the updated correction factors and deviations from routine ionometric electron dosimetry formalisms. According to the recommendations of TRS-398 and TG-51 protocols,

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Dosimetric evaluation of Gafchromic EBT2 film for breast intraoperative electron radiotherapy verification

Cited by 34 publications

References 18 publications

Physical and Dosimetric Aspect of Euromechanics Add-on Multileaf Collimator on Varian Clinac 2100 C/D

Physical and Dosimetric Aspect of Euromechanics Add-on Multileaf Collimator on Varian Clinac 2100 C/D

Validation of Gamma Knife Perfexion Dose Profile Distribution by a Modified Variable Ellipsoid Modeling Technique

Evaluating the performance characteristics of some ion chamber dosimeters in high dose per pulse intraoperative electron beam radiation therapy

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