Monte Carlo study of photon fields from a flattening filter-free clinical accelerator
Abstract
In conventional clinical linear accelerators, the flattening filter scatters and absorbs a large fraction of primary photons. Increasing the beam-on time, which also increases the out-of-field exposure to patients, compensates for the reduction in photon fluence. In recent years, intensity modulated radiation therapy has been introduced, yielding better dose distributions than conventional three-dimensional conformal therapy. The drawback of this method is the further increase in beam-on time. An accelerator with the flattening filter removed, which would increase photon fluence greatly, could deliver considerably higher dose rates. The objective of the present study is to investigate the dosimetric properties of 6 and 18 MV photon beams from an accelerator without a flattening filter. The dosimetric data were generated using the Monte Carlo programs BEAMnrc and DOSXYZnrc. The accelerator model was based on the Varian Clinac 2100 design. We compared depth doses, dose rates, lateral profiles, doses outside collimation, total and collimator scatter factors for an accelerator with and without a flatteneing filter. The study showed that removing the filter increased the dose rate on the central axis by a factor of 2.31 (6 MV) and 5.45 (18 MV) at a given target current. Because the flattening filter is a major sourcemore »
- Authors:
-
- University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)
- Publication Date:
- OSTI Identifier:
- 20775121
- Resource Type:
- Journal Article
- Journal Name:
- Medical Physics
- Additional Journal Information:
- Journal Volume: 33; Journal Issue: 4; Other Information: DOI: 10.1118/1.2174720; (c) 2006 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:
- 61 RADIATION PROTECTION AND DOSIMETRY; COLLIMATORS; DEPTH DOSE DISTRIBUTIONS; DOSE RATES; DOSIMETRY; FILTERS; LINEAR ACCELERATORS; MONTE CARLO METHOD; PATIENTS; PHOTON BEAMS; PHOTONS; RADIATION DOSES; RADIOTHERAPY
Citation Formats
Vassiliev, Oleg N, Titt, Uwe, Kry, Stephen F, Poenisch, Falk, Gillin, Michael T, and Mohan, Radhe. Monte Carlo study of photon fields from a flattening filter-free clinical accelerator. United States: N. p., 2006.
Web. doi:10.1118/1.2174720.
Vassiliev, Oleg N, Titt, Uwe, Kry, Stephen F, Poenisch, Falk, Gillin, Michael T, & Mohan, Radhe. Monte Carlo study of photon fields from a flattening filter-free clinical accelerator. United States. https://doi.org/10.1118/1.2174720
Vassiliev, Oleg N, Titt, Uwe, Kry, Stephen F, Poenisch, Falk, Gillin, Michael T, and Mohan, Radhe. 2006.
"Monte Carlo study of photon fields from a flattening filter-free clinical accelerator". United States. https://doi.org/10.1118/1.2174720.
@article{osti_20775121,
title = {Monte Carlo study of photon fields from a flattening filter-free clinical accelerator},
author = {Vassiliev, Oleg N and Titt, Uwe and Kry, Stephen F and Poenisch, Falk and Gillin, Michael T and Mohan, Radhe},
abstractNote = {In conventional clinical linear accelerators, the flattening filter scatters and absorbs a large fraction of primary photons. Increasing the beam-on time, which also increases the out-of-field exposure to patients, compensates for the reduction in photon fluence. In recent years, intensity modulated radiation therapy has been introduced, yielding better dose distributions than conventional three-dimensional conformal therapy. The drawback of this method is the further increase in beam-on time. An accelerator with the flattening filter removed, which would increase photon fluence greatly, could deliver considerably higher dose rates. The objective of the present study is to investigate the dosimetric properties of 6 and 18 MV photon beams from an accelerator without a flattening filter. The dosimetric data were generated using the Monte Carlo programs BEAMnrc and DOSXYZnrc. The accelerator model was based on the Varian Clinac 2100 design. We compared depth doses, dose rates, lateral profiles, doses outside collimation, total and collimator scatter factors for an accelerator with and without a flatteneing filter. The study showed that removing the filter increased the dose rate on the central axis by a factor of 2.31 (6 MV) and 5.45 (18 MV) at a given target current. Because the flattening filter is a major source of head scatter photons, its removal from the beam line could reduce the out-of-field dose.},
doi = {10.1118/1.2174720},
url = {https://www.osti.gov/biblio/20775121},
journal = {Medical Physics},
issn = {0094-2405},
number = 4,
volume = 33,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}