Figure 1.

Intraobserver reproducibility for test-retest of interfractional shifts for daily image guided alignments. Offline alignments to the planning computed tomography were made twice each (test and retest) by 2 radiation oncologists (observers 1 and 2) for each set of daily images for kV orthogonal imaging with fiducial markers and soft-tissue cone beam computed tomography. The test and retest shift (in millimeters) for each image in each axis were plotted against one another so that correlations could be calculated (Table 3).