HDR后装治疗CT图像至IMRT CT图像变形配准算法研究

摘要

Objective To study a novel method for the high-dose-rate brachytherapy (HDR) CT image to the intensity modulated radiation therapy (IMRT) CT image deformable image registration and dose accumulation.Methods The applicator in the HDR CT image is first segmented and removed,then a deflation step is performed on the applicator-free HDR CT image by solving the Navier-Stokes equation.Demons algorithm is utilized to register the deflated HDR CT image to the IMRT CT image,along with the HDR dose.The deformed HDR dose is then added on the IMRT dose and yield the final accumulated dose.Results The HDR CT image and IMRT CT image,as well as the corresponding dose distribution,from five cervical cancer patients are used for evaluation of the proposed algorithm,the results show that the proposed method can effectively get rid of the influence of the applicator and produce an accurate accumulated dose.Conclusions Dose accumulation and supervision is an important step in adaptive radiotherapy for accurate dose delivery and treatment plan re-optimization.The proposed method in this study can effectively accumulate the HDR dose to the IMRT dose domain,and the accuracy is proved to be sufficient for clinical needs.%目的 研究将高剂量率(HDR)后装治疗CT图像至IMRT的CT图像变形配准及剂量叠加的方法.方法 对含施源器的HDR CT图像进行分割,通过求解Navier-Stokes方程实现对施源器区域收缩变形以去除施源器;然后再利用基于Demons的图像变形配准方法,将去除施源器后的CTHDR图像及其剂量变形至CTIMRT图像域,完成HDR-IMRT CT图像变形配准及剂量累加.结果 利用5例宫颈癌患者放疗期间CTHDR和CTIMRT图像和相应剂量分布图像对算法进行验证,结果表明相对于一般变形配准算法,本算法能有效消除HDR CT图像中施源器对变形配准影响,得到精确的HDR-IMRT累加剂量分布.结论 ART中对总剂量监测和评价可让医生根据患者实际受量,重新优化放疗计划,以实现放射剂量的精确投照.本算法可有效实现宫颈癌患者HDR-IMRT剂量的精确累加,其精度能满足实际临床的需要.