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Updated: Jul 17, 2025
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Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
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A spot-specific range uncertainty framework for robust optimization of proton therapy treatments
Marie Cohilis1, Kevin Souris1, Gregory Buti1
1Institute of Experimental and Clinical Research, UCLouvain, MIRO Lab, Brussels, Belgium.
Medical Physics
|September 7, 2023
Summary
Proton therapy range uncertainties were reduced using a novel spot-specific range uncertainty (SSRU) framework. This method improves organ-at-risk sparing and robust treatment planning in proton therapy.
Area of Science:
- Medical Physics
- Radiation Oncology
- Biomedical Engineering
Background:
- Proton therapy requires accurate range uncertainty estimation for robust treatment planning.
- Current methods recommend a 2.4% range uncertainty, largely based on mean excitation energy.
- Recent advancements allow tissue characterization using water and "dry" material mixtures, potentially reducing uncertainties.
Purpose of the Study:
- To develop an adapted framework for pencil beam scanning robust optimization.
- To implement spot-specific range uncertainty (SSRU) determination.
- To utilize a water-based formalism for reduced range uncertainties and improved organ-at-risk (OAR) sparing.
Main Methods:
- Adapted stoichiometric calibration for molecular decomposition of CT voxels.
- Implemented SSRU calculation in MCsquare Monte Carlo dose engine.
- Assessed the method on three head-and-neck patients comparing SSRU plans with classical flat range uncertainty (FRU) plans.
Main Results:
- Median SSRU was 1.04%, a significant reduction from the 2.4% FRU.
- SSRU plans demonstrated good robustness and superior OAR sparing (e.g., 15.7% mean dose reduction in left parotid).
- Classical plans showed higher, yet unnecessary, robustness levels.
Conclusions:
- The SSRU framework shows promising results for head-and-neck proton therapy.
- Further patient studies are warranted to validate the findings.
- The approach may benefit other tumor sites and generalize to other uncertainties for patient-specific treatments.
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