Pituitary Gland

A small gland in the sella turcica of the sphenoid bone, just below the optic chiasm.

A small gland that makes hormones controlling growth, the thyroid, the adrenal glands and the reproductive glands, often called the body's master gland.

Radiation can cause hypopituitarism — reduced hormone production that may appear years after treatment. It matters mainly for nasopharynx and sinonasal cancers, where the target can extend into or near the sphenoid sinus. In brain treatment it matters for targets near the sella and the base of the frontal and temporal lobes.

Brouwer 2015 notes the gland is very small and generally hard to see on CT; the inner part of the sella turcica can be used as a bony surrogate, and its borders are easiest to set on the sagittal view. The EPTN 2018 atlas adds:

• Oval, up to 12 mm from top to bottom, sitting in the sella turcica.
• The cavernous sinuses border it at the sides (well seen with IV contrast); the brain lies just above it, connected by the pituitary stalk to the hypothalamus.

Because it is so small, Brouwer 2015 suggests expanding it by 5 mm when calculating DVH data, to make the numbers more consistent (while avoiding overlap with the PTV), and recommends a contrast CT with slices of 2 mm or less.