UNASSIGNED: The purpose of this research is to develop a 4DCBCT-based dose assessment method for calculating actual delivered dose for @entity1 with significant respiratory motion or anatomical changes during the course of SBRT. To address the limitation of 4DCT-based dose assessment, we propose to calculate the delivered dose using time-varying ('fluoroscopic') 3D @entity1 images generated from a 4DCBCT-based motion model. The method includes four steps: (1) before each treatment, 4DCBCT data is acquired with the @entity1 in treatment position, based on which a @entity1 -specific motion model is created using a principal components analysis algorithm. (2) During treatment, 2D time-varying kV projection images are continuously acquired, from which time-varying 'fluoroscopic' 3D images of the @entity1 are reconstructed using the motion model. (3) Lateral truncation artifacts are corrected using planning 4DCT images. (4) The 3D dose distribution is computed for each timepoint in the set of 3D fluoroscopic images, from which the total effective 3D delivered dose is calculated by accumulating deformed dose distributions. This approach is validated using six modified @entity2 and different respiratory motions derived from @entity1 data. The estimated doses are compared to that calculated using ground-truth XCAT phantoms. For each XCAT phantom, the calculated delivered @entity5 dose values generally follow the same trend as that of the ground truth and at most timepoints the difference is less than 5%. For the overall delivered dose, the normalized error of calculated 3D dose distribution is generally less than 3% and the @entity5 D95 error is less than 1.5%. XCAT phantom studies indicate the potential of the proposed method to accurately estimate 3D @entity5 dose distributions for SBRT lung treatment based on 4DCBCT imaging and motion modeling. Further research is necessary to investigate its performance for clinical @entity1 data.

4D cone beam CT-based dose assessment for XXXX treatment.

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity2 :: ('MESH:D008175', 'Disease') :: ['XCAT phantoms with lung tumors'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor']
@entity2 :: (MESH:D008175,Disease) :: ['SBRT lung cancer']
