Shielding strategies for Gamma Knife surgery of pituitary adenomas.

OBJECT

The relative performances of two plugging strategies commonly used for pituitary adenoma dose plans were evaluated in terms of factors that influence dose plan quality.

METHODS

Dose plans and clinical treatment data were obtained in 108 patients treated with the Model C Gamma Knife at the University of Virginia. These data were analyzed to determine factors (including plugging strategy) influencing the quality of the dose plans in terms of beam time, conformity, dose to the optic apparatus, and plugging burden. For both secretory and nonsecretory adenomas, beam time (p(secretory) < 0.001, p(nonsecretory) = 0.015) and plugging burden (p(secretory) = 0.007, p(nonsecretory) = 0.038) were reduced when using the customized plugging strategy. The choice of plugging strategy was found to play no significant role in conformity or dose to the optic apparatus. Other factors found to play a significant role in adenoma dose plan quality included tumor volume, prescription dose, and distance from the target to the optic pathways.

CONCLUSIONS

While both plugging strategies were effective at providing the required protection to the optic pathways, the authors found that the customized plugging strategy provided more efficient performance in pituitary adenoma treatments.