Table 1.

Basic characteristics of Leksell Gamma Knife units used for the irradiation of cells. Because the irradiation of cells was performed over a 10 day period, range of days from the last reloading and range of dose rates are given in parenthesis. For further analysis and data reporting in this study, the average dose rate over this 10 day irradiation period was used.

Leksell Gamma Knife Unit	Dose Rate at Reloading [Gy/min]	Time Since Reloading [days]	Experimental Dose Rate [Gy/min]
U	3.759	4396 (4392-4401)	0.770 (0.771-0.768)
4C	3.577	1823 (1819-1828)	1.853 (1.856-1.850)
Perfexion	3.633	589 (585-594)	2.937 (2.942-2.932)