Subproject 6: Development of adaptive dose escalation strategies for MR guided radiotherapy of NSCLC

The aim of this subproject S6 is to develop strategies for personalized, adaptive MR-guided dose escalation strategies for patients with non-small cell lung cancer. To achieve this, diffusion-weighted (DW) MRI is acquired for all patients in the PUMA Trial (S1) before, during and after radiotherapy (RT, Figure 1). In addition, if possible DW-MRI data will be acquired on MR-Linac systems sequentially during MR-guided RT (MRgRT).

In a first work package, acquisition and analysis techniques of DW-MRI in NSCLC patients on the 1.5 T MR-Linac will be optimized using diagnostic DW-MRI as a reference. The potential of DW-MRI as biomarker to identify more aggressive parts of the tumor will be investigated and DW-MRI will be compared to [18F]-FDG PET/CT.

In a second work package, different response adaptive dose escalation strategies will be compared using in silico trials. Finally, automatic planning strategies considering planning CT, MRI and functional target volumes defined by DW-MRI will be developed for future response adaptive MRgRT dose escalation.

Figure 1: Imaging data set of a NSCLC patient before the start of radiotherapy: (A) T2-weighted MRI acquired at the 1.5 T MR-Linac in RT treatment position including delineation of gross tumor volume (GTV) in yellow, (B) diffusion-weighted imaging derived from DW-MRI acquired at the 1.5 T MRI, (C) radiation dose distribution based on clinical target volume (CTV) in red including esophagus as major organ at risk in yellow, (D) [18F]-FDG PET.
Figure 1: Imaging data set of a NSCLC patient before the start of radiotherapy: (A) T2-weighted MRI acquired at the 1.5 T MR-Linac in RT treatment position including delineation of gross tumor volume (GTV) in yellow, (B) diffusion-weighted imaging derived from DW-MRI acquired at the 1.5 T MRI, (C) radiation dose distribution based on clinical target volume (CTV) in red including esophagus as major organ at risk in yellow, (D) [18F]-FDG PET.