Hypersight CBCT Preserves CT-like Radiomic Biomarkers Better Than Conventional CBCT In Pelvic Radiotherapy
Abstract
Purpose
Radiomics-enabled adaptive radiotherapy depends on on-treatment imaging that maintains CT-like quantitative biomarkers. We evaluated whether HyperSight CBCT preserves planning-CT radiomic biomarkers more faithfully than conventional CBCT in pelvic radiotherapy.
Methods
Ten pelvic cancer patients with planning CT, HyperSight CBCT, and conventional CBCT were retrospectively analyzed (first on-treatment scan for each modality). HyperSight and conventional CBCT images were rigidly registered to planning CT using a multi-resolution, intensity-based framework with mutual information. All images were standardized by resampling to 1-mm isotropic voxels. Radiomic features were extracted within the CTV and femur using PyRadiomics (v3.0.1). Statistical analyses were performed in R (v4.5.2) using three complementary radiomic fidelity endpoints: (1) feature-wise CT variance preservation by comparing inter-subject standard deviation ratios relative to CT (to identify variance compression vs. inflation), (2) agreement with CT using intraclass correlation coefficient (ICC), and (3) feature-wise deviation from CT using a scale-robust normalized difference metric with paired one-sided Wilcoxon signed-rank tests (HyperSight < CBCT), controlling multiple comparisons with Benjamini-Hochberg FDR. A CT-defined PCA space was used to assess patient-level Euclidean distance to CT and distributional overlap.
Results
HyperSight improved agreement with planning CT (ICC) for 87/94 CTV features (92.6%) and 70/93 femur features (75.3%). Top-30 median ICC was 0.951 vs 0.773 (CTV) and 0.878 vs 0.586 (femur) for CT vs HyperSight vs CT vs conventional CBCT. In CT-trained PCA space (4 PCs), HyperSight reduced distance to CT by 56.6% in CTV (median 2.17 vs 5.01; p=0.001953; 9/9 closer) and 90.5% in femur (median 6.81 vs 71.98; p=0.001953; 9/10 closer). HyperSight also reduced variance distortion and normalized deviation from CT, with FDR-significant features in both ROIs.
Conclusion
HyperSight CBCT improves radiomic fidelity relative to conventional CBCT at the initial IGRT time point, supporting its use for quantitative imaging and radiomics-driven adaptive radiotherapy workflows.