Fig. 7.

Linear plot of average normal brain isodose volumes per target versus increasing number of targets ($N$) for the four SRS modalities ($GK$ Gamma Knife Perfexion, $CK$ CyberKnife, $NOV$ Novalis, $FFF$ flattening filter free Truebeam). Note the significantly lower slope gradient and y-intercept values for the GK as compared with other linac-based modalities