Target-volume-based prescription selection for specified adverse-effect levels in automated stereotactic radiosurgery

Automated stereotactic radiosurgery (SRS) planning produced consistent dose falloff, enabling adverse-effect-relevant isodose volumes ( $\mathrm{IDV}$ ) to be estimated before plan generation. We derived a direct isoeffect prescription dose ( $D_{\mathrm{RX}}$ ) model from previously validated target-volume ( $V_{\text{target}}$ ) power laws for single-isocenter automated SRS. $\mathrm{IDV}$ coefficients and exponents were modelled as continuous functions of relative isodose level ( $\mathrm{RIL}$ ), allowing $D_{\mathrm{RX}}$ to be solved from $V_{\text{target}}$ , desired $\mathrm{IDV}$ , and HyTEC brain adverse-effect dose thresholds. Across held-out levels, target-level $\mathrm{IDV}$ residuals had a median of 0.2%, an interquartile range of [-5.2%, +7.0%], and a 95% interval of [-12.8%, +27.0%].