Analysis of Volumetric Dosimetry of Target Volumes and Organs at Risk on ICRU Point-Based Dose Planning in CT-Guided HDR Intracavitary Brachytherapy to Carcinoma Cervix

Introduction Intracavitary brachytherapy (ICBT) has been historically planned based on orthogonal X-rays with point A as prescription point and surrogate rectal and bladder points to determine the approximate dose to organs at risk. This was standardized based on ICRU report 38. However, with the availability of better imaging modalities (CT, MRI), it became obvious that those points were poor surrogates for the tumor or the organ at risk. The current study analyzes the volumetric dose distribution to tumor volume and risk organs, from CT image-guided point-based planning done for intracavitary high-dose-rate brachytherapy using Fletcher–Suit–Delclos applicator in locally advanced carcinoma cervix patients. Materials and Methods Fifty-one patients with locally advanced carcinoma cervix who were treated with ICBT were included. Point A-based dose planning was done based on CT images, on Oncentra™ treatment planning software. The doses to bladder point and rectal point were determined and were used for the purpose of dose prescription and optimization. Relevant target volumes and risk organ volumes were determined over the same plans, and dose measurements are taken. They were then analyzed for correlation and linear regression model using IBM SPSS Statistics version 23. Results The point A-based prescription dose did not adequately cover the target volume. CTV 90 obtained only 53.23% (95% CI 49.21–57.25) of the prescribed dose. The bladder point dose correlated well with all sub-volumes, especially D2cc bladder dose ( r = 0.525, p =