Assessment of uncertainties in treatment planning for scanned ion beam therapy of moving tumors.
OBJECTIVE
To provide methods for quantification of uncertainties in 4-dimensional (4D) treatment during treatment planning.


METHODS
Uncertainty information was generated by multiple 4D treatment simulations with varying parameters. Sampled data were analyzed using uncertainty visualization methods that have been added to common treatment plan evaluation methods (eg, dose-volume histogram and dose distribution analysis). To illustrate the potential of the introduced methods, uncertainty analysis was completed for a single lung cancer case using 3 motion mitigation techniques: gating, slice-by-slice rescanning, and breath-controlled rescanning.


RESULTS
By repeating 4D dose calculations with varying parameters, we were able to show local uncertainties in dose distributions and to evaluate the stability of treatment setups. The new methods were found suitable for uncertainty evaluation in 4D treatment planning of moving tumors. Calculation time of the uncertainty base data was time consuming but contrivable overnight.


CONCLUSIONS
Uncertainty analysis and visualization for 4D treatment planning provide an important tool in the decision process for an optimal treatment approach.
Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.
Sebastian
S
Hild
Marco
M
Durante
Christoph
C
Bert
D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005240:Feasibility Studies; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D009068:Movement; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D012119:Respiration; D035501:Uncertainty