Advanced

Influence of dose calculation algorithms on the predicted dose distributions and NTCP values for NSCLC patients

Nielsen, Tine B.; Wieslander, Elinore LU ; Fogliata, Antonella; Nielsen, Morten; Hansen, Olfred and Brink, Carsten (2011) In Medical Physics 38(5). p.2412-2418
Abstract
Purpose: To investigate differences in calculated doses and normal tissue complication probability (NTCP) values between different dose algorithms. Methods: Six dose algorithms from four different treatment planning systems were investigated: Eclipse AAA, Oncentra MasterPlan Collapsed Cone and Pencil Beam, Pinnacle Collapsed Cone and XiO Multigrid Superposition, and Fast Fourier Transform Convolution. Twenty NSCLC patients treated in the period 2001-2006 at the same accelerator were included and the accelerator used for treatments were modeled in the different systems. The treatment plans were recalculated with the same number of monitor units and beam arrangements across the dose algorithms. Dose volume histograms of the GTV, PTV,... (More)
Purpose: To investigate differences in calculated doses and normal tissue complication probability (NTCP) values between different dose algorithms. Methods: Six dose algorithms from four different treatment planning systems were investigated: Eclipse AAA, Oncentra MasterPlan Collapsed Cone and Pencil Beam, Pinnacle Collapsed Cone and XiO Multigrid Superposition, and Fast Fourier Transform Convolution. Twenty NSCLC patients treated in the period 2001-2006 at the same accelerator were included and the accelerator used for treatments were modeled in the different systems. The treatment plans were recalculated with the same number of monitor units and beam arrangements across the dose algorithms. Dose volume histograms of the GTV, PTV, combined lungs (excluding the GTV), and heart were exported and evaluated. NTCP values for heart and lungs were calculated using the relative seriality model and the LKB model, respectively. Furthermore, NTCP for the lungs were calculated from two different model parameter sets. Calculations and evaluations were performed both including and excluding density corrections. Results: There are found statistical significant differences between the calculated dose to heart, lung, and targets across the algorithms. Mean lung dose and V-20 are not very sensitive to change between the investigated dose calculation algorithms. However, the different dose levels for the PTV averaged over the patient population are varying up to 11%. The predicted NTCP values for pneumonitis vary between 0.20 and 0.24 or 0.35 and 0.48 across the investigated dose algorithms depending on the chosen model parameter set. The influence of the use of density correction in the dose calculation on the predicted NTCP values depends on the specific dose calculation algorithm and the model parameter set. For fixed values of these, the changes in NTCP can be up to 45%. Conclusions: Calculated NTCP values for pneumonitis are more sensitive to the choice of algorithm than mean lung dose and V-20 which are also commonly used for plan evaluation. The NTCP values for heart complication are, in this study, not very sensitive to the choice of algorithm. Dose calculations based on density corrections result in quite different NTCP values than calculations without density corrections. It is therefore important when working with NTCP planning to use NTCP parameter values based on calculations and treatments similar to those for which the NTCP is of interest. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3575418] (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
dose calculation algorithm, dose, NTCP, NSCLC, density correction
in
Medical Physics
volume
38
issue
5
pages
2412 - 2418
publisher
American Association of Physicists in Medicine
external identifiers
  • wos:000290625700014
  • scopus:79959555893
ISSN
0094-2405
DOI
10.1118/1.3575418
language
English
LU publication?
yes
id
3eaff424-fd98-4304-84d6-47c0570d6081 (old id 1986303)
date added to LUP
2011-07-01 09:08:50
date last changed
2017-02-05 03:51:28
@article{3eaff424-fd98-4304-84d6-47c0570d6081,
  abstract     = {Purpose: To investigate differences in calculated doses and normal tissue complication probability (NTCP) values between different dose algorithms. Methods: Six dose algorithms from four different treatment planning systems were investigated: Eclipse AAA, Oncentra MasterPlan Collapsed Cone and Pencil Beam, Pinnacle Collapsed Cone and XiO Multigrid Superposition, and Fast Fourier Transform Convolution. Twenty NSCLC patients treated in the period 2001-2006 at the same accelerator were included and the accelerator used for treatments were modeled in the different systems. The treatment plans were recalculated with the same number of monitor units and beam arrangements across the dose algorithms. Dose volume histograms of the GTV, PTV, combined lungs (excluding the GTV), and heart were exported and evaluated. NTCP values for heart and lungs were calculated using the relative seriality model and the LKB model, respectively. Furthermore, NTCP for the lungs were calculated from two different model parameter sets. Calculations and evaluations were performed both including and excluding density corrections. Results: There are found statistical significant differences between the calculated dose to heart, lung, and targets across the algorithms. Mean lung dose and V-20 are not very sensitive to change between the investigated dose calculation algorithms. However, the different dose levels for the PTV averaged over the patient population are varying up to 11%. The predicted NTCP values for pneumonitis vary between 0.20 and 0.24 or 0.35 and 0.48 across the investigated dose algorithms depending on the chosen model parameter set. The influence of the use of density correction in the dose calculation on the predicted NTCP values depends on the specific dose calculation algorithm and the model parameter set. For fixed values of these, the changes in NTCP can be up to 45%. Conclusions: Calculated NTCP values for pneumonitis are more sensitive to the choice of algorithm than mean lung dose and V-20 which are also commonly used for plan evaluation. The NTCP values for heart complication are, in this study, not very sensitive to the choice of algorithm. Dose calculations based on density corrections result in quite different NTCP values than calculations without density corrections. It is therefore important when working with NTCP planning to use NTCP parameter values based on calculations and treatments similar to those for which the NTCP is of interest. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3575418]},
  author       = {Nielsen, Tine B. and Wieslander, Elinore and Fogliata, Antonella and Nielsen, Morten and Hansen, Olfred and Brink, Carsten},
  issn         = {0094-2405},
  keyword      = {dose calculation algorithm,dose,NTCP,NSCLC,density correction},
  language     = {eng},
  number       = {5},
  pages        = {2412--2418},
  publisher    = {American Association of Physicists in Medicine},
  series       = {Medical Physics},
  title        = {Influence of dose calculation algorithms on the predicted dose distributions and NTCP values for NSCLC patients},
  url          = {http://dx.doi.org/10.1118/1.3575418},
  volume       = {38},
  year         = {2011},
}