Validation of Deformable Dose Accumulation for Cervical Cancer Interstitial Brachytherapy

Accuracy of deformable dose accumulation is challenging in brachytherapy. The purpose of this study is to quantitatively analyze factors impacted on final dose in deformable dose accumulation. Six patients underwent brachytherapy were collected for dose accumulation. A biomechanical model-based registration algorithm was used. Dice similarity coefficient was introduced to quantify the deformable image registration accuracy. Deformable dose was calculated for bladder and rectum, respectively, and D0.1cc, D1cc, D2cc as dose-volume parameters were used to evaluated dose accumulation variation. When selected different image as reference, large dose variation was observed on bladder (34.7%) and rectum (32.7%) for individual patient. For bladder, dose accumulation result was much more strongly related to relative volume than dice similarity coefficient. The results indicate that registration algorithm performed differently on bladder and rectum. Strong negative correlation was found between relative volume and accumulation dose-volume parameters of D1cc and D2cc in bladder. However, DSC score is shown less notable correlated with these dose parameters. Our results suggest that bladder/rectum filling protocol should be used in clinical implementation to reduce variation in dosimetric result.