The authors present a new method for using the Leksell γ knife. To obtain isodose curves that are best suited to the target volumes, they propose, for a given shot, combining on the same helmet collimators of different sizes (4, 8, 14, and 18 mm), as well as plugs. The method for optimizing the positions of the collimators and of the plugs on the helmets is described. Tests were carried out on fictitious volumes to compare conventional treatment plans with those obtained after optimization. The collimator combination method demonstrates an increase in dose plan quality as measured by the conventional dose quality indexes found in the literature, as well as savings of irradiation and patient positioning time. The authors demonstrate that it is thus possible to achieve a considerable improvement in γ-knife performance, without changing its main technical characteristics.