Vector Analysis of Prostate Patient Setup With Image-Guided Radiation Therapy via kV Cone Beam Computed Tomography

Daily imaging is recommended for prostate cancer IMRT patients in order to know the 3D (vector) position of the CTV and to ensure that it is always within the PTV margin. Correcting the data set by the average shift from the first 5 days reduces the overall number of outlier days but does not eliminate them completely.