Additionally, eq. (5) was used to determine if the errors were within our tolerance. If eq. (5) was satisfied, the calculation result was acceptable.(5)ΔD=ΔTt2+ΔRr2<1,where t is a translational tolerance factor and r is a rotational tolerance factor. At our facility, setup tolerance is set at 2 mm. 19 Moreover, the angle corresponding to a 2‐mm displacement over 7.5 cm (one half of the maximum irradiation field) is 1.53°. Therefore, t=2 and r=1.53 were used in this study.