  Introduction: Lung cancer is a leading cause of cancer-related mortality, and
stereotactic body radiotherapy (SBRT) has become a standard treatment for
early-stage lung cancer. However, the heterogeneous response to radiation at
the tumor level poses challenges. Currently, standardized dosage regimens lack
adaptation based on individual patient or tumor characteristics. Thus, we
explore the potential of delta radiomics from on-treatment magnetic resonance
(MR) imaging to track radiation dose response, inform personalized radiotherapy
dosing, and predict outcomes. Methods: A retrospective study of 47 MR-guided
lung SBRT treatments for 39 patients was conducted. Radiomic features were
extracted using Pyradiomics, and stability was evaluated temporally and
spatially. Delta radiomics were correlated with radiation dose delivery and
assessed for associations with tumor control and survival with Cox regressions.
Results: Among 107 features, 49 demonstrated temporal stability, and 57 showed
spatial stability. Fifteen stable and non-collinear features were analyzed.
Median Skewness and surface to volume ratio decreased with radiation dose
fraction delivery, while coarseness and 90th percentile values increased.
Skewness had the largest relative median absolute changes (22%-45%) per
fraction from baseline and was associated with locoregional failure (p=0.012)
by analysis of covariance. Skewness, Elongation, and Flatness were
significantly associated with local recurrence-free survival, while tumor
diameter and volume were not. Conclusions: Our study establishes the
feasibility and stability of delta radiomics analysis for MR-guided lung SBRT.
Findings suggest that MR delta radiomics can capture short-term radiographic
manifestations of intra-tumoral radiation effect.
