A full quantitative analysis of 18 MV photon beam from 2100 C/D-Varian clinical linear accelerator with and without flattening filter

Authors

  • M. Allahverdi Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
  • M. Hoseini-Ghahfarokhi Department of Radiology and Nuclear Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
  • M. Shahriari Department of Nuclear Engineering, Shahid Beheshti University, Tehran, Iran
  • M. Zabihzadeh Cancer, Environmental and Petroleum Pollutants Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
  • M.R. Ay Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
  • S.R. Mahdavi Department of Medical Physics, Iran University of Medical Sciences, Tehran, Iran
Abstract:

Background: During intensity modulated radiation therapy (IMRT) technique, theoretically, presence of flattening filter (FF) across the beamline of clinical linear accelerator (linac) is not essential to obtain uniform lateral profiles due to intensity modulation of photon beams by multileaf collimators (MLCs). The aim of this study was to investigate the dosimetrical properties of 18 MV photon beam-Varian linac with and without FF. Materials and Methods: All dose measurements were performed on 18 MV, FF mode-Varian 2100C/D linac. The FF and flattening filter free (FFF) modes of linac were modeled by MCNPX 2.4. code. The photon and contaminant electrons spectra, dose rate, present depth doses (PDD), lateral dose profiles, total and collimator scatter factors and out of field doses were calculated and compared with and without FF. Results: Removing the FF increased the photon and contaminant electron fluences by factors of 5.48 and 3.94 for a 5 × 5 cm2 field size, respectively. The surface dose increased up to 155%. The flatness of dose profile was disturbed and deteriorated with increase of field size. Despite the dependence of the total scattering factor on field size, the variation of collimator scattering factors was neglected. The out-of-field dose decreased about 81.5 % for a 5 × 5 cm2 field size. Conclusion: Removing FF from the linac head increases the dose rate and decreases the out-of-field dose, but the increased skin dose and deteriorated flatness of lateral dose profile are the main disadvantages of the FFF mode.

Upgrade to premium to download articles

Sign up to access the full text

Already have an account?login

similar resources

Beam Characterization of 10-MV Photon Beam from Medical Linear Accelerator without Flattening Filter

AIM This work investigated the dosimetric properties of a 10-MV photon beam emitted from a medical linear accelerator (linac) with no flattening filter (FF). The aim of this study is to analyze the radiation fluence and energy emitted from the flattening filter free (FFF) linac using Monte Carlo (MC) simulations. MATERIALS AND METHODS The FFF linac was created by removing the FF from a linac ...

full text

Investigation of Neutron Contamination of Flattening Filter and Flattening Filter-Free 10-MV Photon Beams in Elekta InfinityTM Accelerator

Introduction: This study aimed to measure the neutron contamination of flattening filter (FF) and flattening filter-free (FFF) 10-MV photon beams delivered by the Elekta InfinityTM accelerator. Material and Methods: The photoneutron spectrum produced by the Linac head was evaluated using a Monte Carlo (MC) simulation. The geometry ...

full text

Advantages and disadvantages of removed flattening filter Linac: A Monte Carlo study on full quantitative dosimetric data of 18 MV-Varian Linac

Introduction: During intensity modulated radiation therapy (IMRT) technique, theoretically, presence of flattening filter (FF) across the beamline of clinical linear accelerator (linac) is not essential to obtain uniform lateral profiles due to intensity modulation of photon beams by multileaf collimators (MLCs). The aim of this study was to investigate the dosimetrical propert...

full text

Investigations of parameters affecting the photon energy spectra of an 18 MV Varian 2100C/D linear accelerator

Radiotherapy using linear accelerators is known as an effective modality for cancer treatment. The photons energy of treatment beams significantly affect the dose distribution. Therefore, it is important to accurately evaluate the photon energy spectra. In this study, MCNPX Monte Carlo code (version 2.6.0) was used to simulate an 18 MV photon beam of a Varian 2100C/D linear accelerator. By matc...

full text

Monte Carlo estimation of electron contamination in a 18 MV clinical photon beam

Background: The electron contamination may reduce or even diminish the skin sparing property of the megavoltage beam. The detailed characteristics of contaminant electrons are presented for different field sizes and cases. Materials and Methods: The Monte Carlo code, MCNPX, has been used to simulate 18 MV photon beam from a Varian Linac-2300 accelerator. All dose measurements were car...

full text

Commissioning of TrueBeamTM Medical Linear Accelerator: Quantitative and Qualitative Dosimetric Analysis and Comparison of Flattening Filter (FF) and Flattening Filter Free (FFF) Beam

Motive of the study is to present quantitative and qualitative analysis and comparison of beam data measurement with FF (flattening filter) and FFF (flattening filter free) beam in a Varian TrueBeamTM Medical Linear Accelerator. Critique of beam characterization and evolution of dosimetric properties for 6 MV, 10 MV, 15 MV FF beam and 6 MVFFF, 10 MVFFF FFF beam has been carried out. We performe...

full text

My Resources

Save resource for easier access later

Save to my library Already added to my library

{@ msg_add @}


Journal title

volume 17  issue 1

pages  137- 146

publication date 2019-01

By following a journal you will be notified via email when a new issue of this journal is published.

Keywords

Hosted on Doprax cloud platform doprax.com

copyright © 2015-2023