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Prediction of stopping-power ratios in flattening-filter free beams.

Ceberg, Crister LU ; Johnsson, Stefan; Dalaryd, Mårten LU and Knöös, Tommy LU (2010) In Medical Physics 37(3). p.1164-1168
Abstract
PURPOSE: In recent years, there has been an increasing interest in flattening-filter free (FFF) beams. However, since the removal of the flattening filter will affect both the mean and the variance of the energy spectrum, current beam-quality specifiers may not be adequate for reference dosimetry in such beams. The purpose of this work was to investigate an alternative, more general beam-quality specifier. METHODS: The beam-quality specifier used in this work was a combination of the kerma-weighted mean and the coefficient of variation of the linear attenuation coefficient in water. These parameters can in theory be determined from narrow-beam transmission measurements using a miniphantom "in-air," which is a measurement condition well... (More)
PURPOSE: In recent years, there has been an increasing interest in flattening-filter free (FFF) beams. However, since the removal of the flattening filter will affect both the mean and the variance of the energy spectrum, current beam-quality specifiers may not be adequate for reference dosimetry in such beams. The purpose of this work was to investigate an alternative, more general beam-quality specifier. METHODS: The beam-quality specifier used in this work was a combination of the kerma-weighted mean and the coefficient of variation of the linear attenuation coefficient in water. These parameters can in theory be determined from narrow-beam transmission measurements using a miniphantom "in-air," which is a measurement condition well suited also to small and nonstandard fields. The relation between the Spencer-Attix stopping-power ratios and this novel beam-quality specifier was described by a simple polynomial. For reference, the authors used Monte Carlo calculated spectra and stopping-power data for nine different beams, with and without flattening filter. RESULTS: The polynomial coefficients were obtained by least-squares optimization. For all beams included in this investigation, the average of the differences between the predicted and the Monte Carlo calculated stopping-power ratios was 0.02 +/- 0.17% (1 SD) (including TomoTherapy and CyberKnife example beams). CONCLUSIONS: An alternative dual-parameter beam-quality specifier was investigated. The evaluation suggests that it can be used successfully to predict stopping-power ratios in FFF as well as conventional beams, regardless of filtration. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
dosimetry, phantoms, Monte Carlo methods, radiation therapy
in
Medical Physics
volume
37
issue
3
pages
1164 - 1168
publisher
American Association of Physicists in Medicine
external identifiers
  • wos:000275160300023
  • pmid:20384253
  • scopus:77749292384
ISSN
0094-2405
DOI
10.1118/1.3314074
language
English
LU publication?
yes
id
29cdd76c-10fa-47d3-a4b0-f04f3cf4c47c (old id 1595370)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/20384253?dopt=Abstract
date added to LUP
2010-05-04 22:25:47
date last changed
2018-05-29 09:22:24
@article{29cdd76c-10fa-47d3-a4b0-f04f3cf4c47c,
  abstract     = {PURPOSE: In recent years, there has been an increasing interest in flattening-filter free (FFF) beams. However, since the removal of the flattening filter will affect both the mean and the variance of the energy spectrum, current beam-quality specifiers may not be adequate for reference dosimetry in such beams. The purpose of this work was to investigate an alternative, more general beam-quality specifier. METHODS: The beam-quality specifier used in this work was a combination of the kerma-weighted mean and the coefficient of variation of the linear attenuation coefficient in water. These parameters can in theory be determined from narrow-beam transmission measurements using a miniphantom "in-air," which is a measurement condition well suited also to small and nonstandard fields. The relation between the Spencer-Attix stopping-power ratios and this novel beam-quality specifier was described by a simple polynomial. For reference, the authors used Monte Carlo calculated spectra and stopping-power data for nine different beams, with and without flattening filter. RESULTS: The polynomial coefficients were obtained by least-squares optimization. For all beams included in this investigation, the average of the differences between the predicted and the Monte Carlo calculated stopping-power ratios was 0.02 +/- 0.17% (1 SD) (including TomoTherapy and CyberKnife example beams). CONCLUSIONS: An alternative dual-parameter beam-quality specifier was investigated. The evaluation suggests that it can be used successfully to predict stopping-power ratios in FFF as well as conventional beams, regardless of filtration.},
  author       = {Ceberg, Crister and Johnsson, Stefan and Dalaryd, Mårten and Knöös, Tommy},
  issn         = {0094-2405},
  keyword      = {dosimetry,phantoms,Monte Carlo methods,radiation therapy},
  language     = {eng},
  number       = {3},
  pages        = {1164--1168},
  publisher    = {American Association of Physicists in Medicine},
  series       = {Medical Physics},
  title        = {Prediction of stopping-power ratios in flattening-filter free beams.},
  url          = {http://dx.doi.org/10.1118/1.3314074},
  volume       = {37},
  year         = {2010},
}