Dust radius as a function of bolometric luminosity (R − L_bol relation). OI measured sizes are shown in red and RM measured sizes are shown in blue. The typical 0.3 dex uncertainty in L_bol is indicated in the right corner. The solid lines show our best-fit results, with the shaded regions showing the 1σ uncertainties of the fittings, while the dotted lines represent the fitting results with the slopes m fixed to 0.5. Our best-fitting R − L_bol relations are consistent with the slope of 0.5 within 1σ. The bottom panel shows the dust radius residuals from the fitted relation with fixed slopes of 0.5.