Die Wirkung der Strahlendosis auf das optische System und die gefährdeten Organe bei Patient*Innen mit radiochirurgisch behandelten Hypophysenadenomen

Gamma Knife radiosurgery is commonly used in the multimodal management of patients with pituitary adenomas. Regarding the radiation exposure of risk structures such as the optic nerve or the optic chiasm, a safety distance of two millimeters is often considered as crucial in treatment planning. Moreover, varying levels of radiation tolerance have been reported in the literature for organs at risk in close proximity to the pituitary adenoma. The aim of this study is to evaluate the effect of different radiation doses on the critical structures via the endocrinological, ophthalmological and neurological outcome.

A retrospective analysis of 139 patients with pituitary adenomas, who underwent at least one Gamma Knife radiosurgical treatment between 2000 and 2022, was performed. The radiation dose to the defined critical structures as well as the minimal distance between the pituitary adenoma and these structures were measured with the Elekta Planning System.

The majority of the study population (134/139, 96%) underwent a previous surgical removal of the pituitary adenoma. The pituitary adenomas were hormone-active in 92/139 (66%) patients. The median treatment volume was 4.6 cm3 (0.5-16.7). In 3/139 (2%) patients, a compression of the optic chiasm or optic nerve could be observed.

Of 130/139 (94%) with available pre-radiosurgical planning data, the maximal radiation doses on the optic chiasm were 6.2 Gy (1.5-16.3). After Gamma Knife radiosurgical treatment, the majority of patients (95%) with radiological follow-up had a decreased tumor volume. Furthermore, the majority of the patients (96%) did not have any worsening of the ophthalmological deficits.

Radiosurgical treatment is a safe therapy option for pituitary adenoma patients without worsening of ophthalmological deficits.