The Management of Pituitary Adenomas by Yttrium-90 Interstitial Irradiation

Publisher Summary This chapter describes the management of pituitary adenomas by yttrium-90 interstitial irradiation. The main landmark showing the position of the midline of the pituitary fossa that is visible on posteroanterior screening during the implantation procedure is the dorsum sellae. It is found that this structure must be visible on a preliminary 25–30° anteroposterior coned view of the pituitary fossa. A less satisfactory but feasible landmark indicating the midline is the fossa floor, and this is often seen on a straight AP film. It is found that when the clinician specifies the dose as being so many centigrays, the intention is to give that dose to each of the needle holes in the anterior wall of the fossa and also to the expected anatomical position of the diaphragma sellae at its hottest point. The relevant length of the fossa is in the plane of the proposed yttrium seed. This plane is obtained by laying a ruler on a lateral skull radiograph, running from the proposed point of the needle entry through the nostril to the mid-depth of the fossa, which is taken perpendicular to the center of the incoming yttrium seed.