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. 2009 Nov 17;36(12):5622–5632. doi: 10.1118/1.3259729

Figure 2.

Figure 2

Full width at half maximum (FWHM) of profile under the spot size camera as a function of distance between the target and the detector. Squares: 6 MV, inplane; circles: 6 MV, crossplane; triangles: 18 MV, inplane; diamonds: 18 MV, crossplane. Open circles are simulated results using a 14 MeV photon beam with a spot size of 1.5 mm FWHM. Lines are fits to Eq. 2. Solid lines, 6 MV; dashed lines, 18 MV; dotted line, simulated results. The left inset shows a schematic drawing of a single slit of the spot camera. The right inset shows the variables used in the determination of the position of the beam spot at the x-ray target.