Figure 11.

(A, B) T1‐weighted postcontrast and T2‐weighted transverse images of a 4th ventricle choroid plexus tumor. (C) Dog positioned in stereotactic thermoplastic head restraint. The VARIAN trueBEAM linear accelerator¹¹ is equipped with a 2.5‐mm leaf multileaf collimator, a couch with 0.1‐mm incremental movement, and on‐board Kv, MV and cone beam CT to allow precise stereotactic delivery of radiation. (D) BrainLab planning system¹⁰ showing the planned treatment trajectories to the tumor (magenta) sparing defined vital structures (eyes‐red/green, inner ears‐yellow/blue). (E) Transverse CT image with isodose planning superimposed (images courtesy of M. Kent, UC Davis).