This study introduces a novel approach for screening bone alterations in the femoral head and neck (H&N) of prostate cancer (PCa) and rectal cancer (RCa) patients during helical tomotherapy (HT) using megavoltage computed tomography (MVCT) images. The goal is to identify robust radiomic features (RFs) with the highest percentage changes during treatment and examine their correlation with the administered dose.

Reproducible RFs were identified through a test-retest analysis using a cheese phantom. This study involved 20 male patients (10 PCa, 10 RCa). The left and right femoral H&N regions were segmented on MVCT images from the initial, middle, and final HT sessions. Absolute RF values and relative percentage changes were analyzed using repeated measures analysis of variance (ANOVA). The Pearson correlation coefficient with Benjamini-Hochberg adjustment (q < 0.05) was used to evaluate the relationship between altered RFs and the dose (Gy).

The femoral H&N had the highest relative percentage changes (RPCs) for intensity-histogram (IH) and intensity-based (IB) RFs, respectively, with texture-based RFs providing insights into radiotherapy-induced changes. Strong correlations (r ~ -0.7) were observed between changes in H&N RFs and dose (Gy) in PCa. For RCa, IB features, including the IB_Coefficient_of_Variation (r = 0.54) for the neck, and IH RFs, such as IH_Minimum_Histogram_Gradient (r = -0.51) and IB_Robust_Mean_Absolute_Deviation (r = 0.55) for the head, showed significant correlations.

Among robust RFs, the most highly correlated with dose alterations were IB, IH, and gray-level co-occurrence matrix (GLCM)-based RFs. The RFs at mid- and end-treatment varied with dose fractionation. Percentage changes in robust MVCT features during HT may serve as early markers.