Figure 2.

An example of the measured (data points) and fitted (straight lines) dose ratios for closed multileaf collimator $(R_{\text{cMLC}})$ with and without a cone for the 6‐MV 6EX linear accelerator. Measurements were made in air with the cone (filled triangle), in air without the cone (filled cross), and in solid water at depth $d_{\text{max}}$ without the cone (solid circle). Ionization chambers A12 and TDC100 were used. The discrepancy between the two sets of data without the cone (solid cross and solid circle) is within the accuracy of the method.