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Sensitivity analysis of the relative biological effectiveness predicted by the local effect model
T Friedrich1, R Grün, U Scholz
1GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.
Physics in Medicine and Biology
|September 13, 2013
Summary
The Local Effect Model (LEM) predicts relative biological effectiveness (RBE) in particle therapy. Sensitivity analysis shows RBE changes are typically smaller than input parameter changes, aiding treatment plan uncertainty estimation.
Area of Science:
- Particle radiobiology
- Radiation oncology
- Biophysics
Background:
- Relative biological effectiveness (RBE) is crucial for particle radiobiology and therapy.
- The Local Effect Model (LEM) is a key tool for predicting RBE.
- Understanding RBE's dependence on input parameters is vital for accurate predictions.
Purpose of the Study:
- To elucidate the sensitivity of RBE predictions from the LEM to its input parameters.
- To analyze the theoretical basis and practical implications of each LEM parameter.
- To assess the impact of parameter variations on RBE for different irradiation scenarios.
Main Methods:
- Systematic sensitivity analysis of LEM input parameters.
- Theoretical considerations of parameter influence on RBE.
- Simulations for fictitious cell lines with varying alpha/beta ratios (2 Gy and 10 Gy).
- Evaluation under both track segment and spread-out Bragg peak irradiation conditions.
Main Results:
- Changes in most LEM parameters result in equal or smaller relative changes in predicted RBE values.
- The threshold dose (Dt) can be a free fit parameter for high LET dose response curves.
- Sensitivity analysis provides insights into the theoretical meaning of each parameter.
Conclusions:
- The LEM is robust, with RBE predictions showing limited sensitivity to individual parameter variations.
- Findings support the use of LEM for treatment plan assessment and uncertainty quantification in particle therapy.
- This work enhances the understanding and application of the LEM in radiobiology.
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