A novel treatment-planning module to account for lung modulation effects in particle therapy of lung cancer patients

• Applicant: Dr. Kilian-Simon Baumann
• Subject Area: Medical Physics, Biomedical Technology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 511593530

Lung cancer is the deadliest cancer worldwide. Particle therapy is a promising alternative since it allows for a highly conformal dose deposition in the target whereas an excellent sparing of surrounding healthy tissue is possible. However, the heterogeneous structure of the lung tissue leads to a modulation of the dose distribution and, especially, a broadening of the Bragg peak, potentially resulting in an underdosage of the target volume. Unfortunately, the structure of the lung tissue is not sufficiently resolved in clinical treatment-planning CT-images and, hence, these lung modulation effects are not being considered at all. In order to describe lung modulation effects, our working group has introduced the parameter “modulation power” which quantifies the broadening of the Bragg peak. In preliminary studies, a method was proposed to determine the modulation power of lung tissue patient-individually and spatially resolved on the basis of clinical CT-images. Using the concept of modulation power, a Monte Carlo-based solution was proposed to reproduce lung modulation effects on clinical CT-data, enabling, for the first time, a quantification of the underdosage of the target volume for clinical treatment plans. The goal of the proposed research project is the modification of the freely available treatment-planning system matRad to automatically identify and compensate for lung modulation effects patient-individually, thus granting a more accurate dose calculation in particle therapy of lung cancer patients. Hence, our method of determining the modulation power of lung tissue patient-individually and spatially resolved on the basis of clinical CT-images will be implemented in matRad. A method to account for lung modulation effects on the stage of physical dose calculation is already available for matRad. A method to consider lung modulation effects on the biological dose of carbon ions will be developed in this project and implemented in matRad. The complete treatment-planning workflow with the modified matRad will be validated in an experimental setup. Furthermore, modulation powers of human lung tissue will be determined for a large patient collective and the impact of frequent comorbidities like COPD on the modulation power will be investigated. With the help of a treatment-planning study, a guideline will be derived on how to treat lung cancer patients with particles to minimize dose uncertainties due to lung modulation effects. This guideline serves all particle therapy centers not able to utilize the treatment-planning system matRad modified in this study due to legal restrictions.

• DFG Programme: Research Grants