What dose and planning techniques would you use for LINAC based SRS of a craniopharyngioma with reasonable distance from critical optics and brainstem OARs?

I would recommend a single fraction of 12 Gy, taking into consideration the optical structures. Our early experience using GammaKnife in 14 patients treated for craniopharyngioma ranged from 11 to 20 Gy with a median of 14 Gy in a single fraction; Amendola et al Pediatric Blood and Cancer August 2003. A recent review by Jung et al including data from Japan was reported in "Applied Radiation Oncology" in June 2015 recommending doses 11.5 Gy for children and in South Korea reported similar doses. ...