Figure 4.

Sample IMRT QA report from LANTIS. (Note: patient identifiers and physicist's signatures were removed.) The QA method in this report is the 2D calculation using a ray trace through a solid water phantom. All SSDs and depths are calculated from intersections of each ray line with the phantom surface planes. This is done for each point on the $2\text{mm}\times 2\text{mm}$ grid on the coronal plane through isocenter. The resulting calculated “virtual film” (middle left) is compared against the corresponding $4\text{mm}\times 4\text{mm}$ Pinnacle calculation (top left) in order to determine the error (bottom left), distance to agreement (top right), and decision (middle right) maps. The calculated data were interpolated onto a common $1\text{mm}\times 1\text{mm}$ grid.