Correlation of Dose-Volume Histogram Metrics with Radiobiological Indices in Cervical Cancer Patients Undergoing Brachytherapy

Dose-volume histogram (DVH) metrics are routinely used to evaluate brachytherapy plans for cervical cancer and their association with radiobiological outcomes is seldom verified for individual institutional datasets. This study presents a correlational analysis of DVH metrics with radiobiological indices of 45 cervical cancer patients undergoing brachytherapy at National Hospital, Abuja. CT-based treatment planning was used to contour the high-risk clinical target volume (HR-CTV), intermediate-risk clinical target volume (IR-CTV), bladder, and rectum. DVH metrics (HR-CTV D90, D98 and EQD2-converted D2cc for bladder and rectum) were extracted from the treatment planning system (TPS). Tumor Control Probability (TCP) was computed using linear-quadratic (LQ) model, while Normal Tissue Complication Probability (NTCP) was estimated using Lyman-Kutcher-Burman (LKB) model. Pearson correlation analysis was performed using Python to determine the strength and significance of associations between DVH metrics and radiobiological indices. From the results, the mean ± SD doses were found to be 5.78 ± 0.35 Gy (HR-CTV D90) and 4.24 ± 0.29 Gy (IR-CTV D90). TCP modeling yielded high control probabilities for HR-CTV (99.97% for D90; 99.99% for D98) and lower values for IR-CTV (85.38% and 92.04%, respectively). NTCP remained negligible (0.0004%) for both bladder and rectum, with all D2cc values below the 90 Gy EQD2 GEC-ESTRO constraint. Strong positive correlations were observed between TCP and HR-CTV D90 EQD2 (r = +0.889, p < 0.001). In contrast, TCP correlated weakly and non-significantly with HR-CTV D98 (r = +0.239, p = 0.1143). For organs at risk, rectum D2cc showed a strong correlation with NTCP (r = +0.836),