The field output factor (|${\varOmega}_{Q_{\mathrm{clin}},{Q}_{\mathrm{msr}}}^{f_{\mathrm{clin}},{f}_{\mathrm{msr}}}$|) of TrueBeam STx plotted against the square field sizes (insets) and the relative difference of each value from the |${\varOmega}_{Q_{\mathrm{clin}},{Q}_{\mathrm{msr}}}^{f_{\mathrm{clin}},{f}_{\mathrm{msr}}}$| of the microDiamond detector. OFdet values are plotted only for the microSilicon detector.