Hybrid MV-kV 3D respiratory motion tracking during radiation therapy with low imaging dose.

摘要: A novel real-time adaptive MV-kV imaging framework for image-guided radiation therapy is developed to reduce the thoracic and abdominal tumor targeting uncertainty caused by respiration-induced intrafraction motion with ultra-low patient dose. In our method, continuous stereoscopic used at beginning of a delivery several seconds measure implanted marker positions. After this period, kV imager switched off except times when no fiducial detected in cine-MV images. The 3D time-varying positions are estimated combining MV 2D projection data correlations between directional components established from period updated afterwards; particular, most likely position assumed be on line that has shortest distance first principal component segment constructed previous trajectory points. An windowed auto-regressive prediction utilized predict short time later (310 ms 460 ms study) allow tracking system latency. To demonstrate feasibility evaluate accuracy proposed computer simulations were performed both arc fixed-gantry deliveries using 66 h retrospective 42 patients treated or cancers. reveal hybrid approach, smaller than 1.2 mm 1.5 mm root-mean-square error can achieved latency 310 ms 460 ms, respectively. Because only extra dose reduced an order magnitude compared imaging, while clinical cancers maintained. Furthermore, additional hardware required method.