Stereotactic radiosurgery for Cushing's disease

Coronal section CT image through the sella turcica and anterior pituitary gland of a patient with Cushing's disease. The brown areas represent brain or other tissue; the black areas represent cerebrospinal fluid (eg, the upper center vertical space is the third ventricle) or air-filled sinuses (eg, the space just below center is the sphenoid sinus); the white areas represent bone (eg, the highest points represent the clinoid processes). A computer-assisted stereotactic "photon knife" treatment plan is superimposed on the CT image; it employs two isocenters of 15 Gy radiation delivered by a linear accelerator, one in each half of the anterior pituitary. Each concentric circle is an isorad 1 Gy less than the next inner circle. The optic chiasm will be exposed to less than 8 cGy of radiation.