FIG. 4.

Comparison of perspective correction factor, c’, of Cherenkov-to-dose in vertical and horizontal directions for right anterior oblique (RAO), left anterior oblique (LAO), and anterior–posterior (AP): (a) Schematics of the experimental setup that shows the positions of RAO, LAO, and AP board in the TSE stand and location of the Cherenkov camera, the isocenter, and their corresponding coordinates from the top view. (b) CF in vertical direction. (c) CF in horizontal directions. The dose was determined by optical stimulated luminescent dosimeter and verified by diode measurements in all three polyvinyl chloride (PVC) board orientations (Table I). “CF fit dual” in Fig. 4b is obtained by fitting the perspective correction factor in Fig. 3e for the dual fields. The inverse square factor, ${\text{CDD}}_0^2/{\text{CDD}}^2$, for AP, RAO, LAO in the vertical positions are the same (INV) in Fig. 4a and in the horizontal positions (AP INV, RAO INV, and LAO INV) in Fig. 4b. All profiles have been smoothed with a median filter. [Color figure can be viewed at wileyonlinelibrary.com]