Microstructural modelling based on diffusion weighted imaging to guide dose painting in carbon ions for large sacral
Giovanni Parrella1, Letizia Morelli1, Giuseppe Magro2
1Politecnico di Milano, Department of Electronics, Information and Bioengineering, Milano, Italy.
Physics and Imaging in Radiation Oncology
|January 5, 2026
Summary
Dose painting in carbon ion radiotherapy improves tumor control probability by adapting radiation dose based on microstructural imaging. This strategy enhances treatment efficacy while sparing healthy tissues.
Area of Science:
- Radiation Oncology
- Medical Imaging
- Biophysics
Background:
- Dose Painting (DP) addresses tumor heterogeneity in radiotherapy.
- Carbon Ion Radiotherapy (CIRT) offers potential for targeted cancer treatment.
- Diffusion-weighted Magnetic Resonance Imaging (DWI) provides microstructural insights.
Purpose of the Study:
- To evaluate a DP approach in CIRT using DWI-derived cell count estimates.
- To optimize DP strategies for sacral chordoma (SC) treatment.
- To assess the impact of DP on tumor control probability (TCP) and organ at risk (OAR) sparing.
Main Methods:
- Analysis of 37 large sacral chordoma patients.
- Voxel-wise cell count estimation from DWI using a microstructural model.
- DP optimization guided by a Poisson-based TCP model and tested with dose redistribution (DR) and dose escalation (DE) strategies.
Main Results:
- DE plans significantly increased TCP from 75.5% to 83.3% (p < 0.001).
- DR plans showed a modest TCP gain of 1.8%.
- Both DE and DR plans met clinical acceptability criteria with no significant OAR dose or LETd increase.
Conclusions:
- DP in CIRT, guided by microstructural modeling, shows promise for improving TCP.
- This approach can potentially spare OARs effectively.
- Microstructural modeling aids in biologically targeted radiotherapy planning.
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