Table 1.

Comparison of Agility and MLCi heads. Field sizes are defined at isocenter. In the ranges of travel, a negative value indicates the direction of insertion and a positive value indicates the direction of withdrawal.

Characteristic	Agility Head	MLCi Head
Maximum field size (cm)	$40\times 40$	$40\times 40$
Leaf pitch (cm)	0.5	1.0
X a collimator range with respect to central axis (cm)	Not applicable	$-12.5$ to 20
Leaf guide range with respect to central axis (cm)	5 to 20	Not applicable
MLC leaf range with respect to guide (cm)	$-20\hspace{0.17em}\text{to}\hspace{0.17em}0$	Not applicable
MLC range with respect to central axis (cm)	$-15\hspace{0.17em}\text{to}\hspace{0.17em}20$	$-12.5\hspace{0.17em}\text{to}\hspace{0.17em}20$
Y a collimator range with respect to central axis (cm)	$-12\hspace{0.17em}\text{to}\hspace{0.17em}20$	0 to 20
Focus – MLC distance (cm)	31.8	29.8
MLC thickness (cm)	9.0	7.5
Maximum MLC leaf speed (${\text{cms}}^{-1}$)	3.5	2.0
Maximum X a collimator / leaf guide speed (${\text{cms}}^{-1}$)	3.0	2.0
Maximum Y a collimator speed (${\text{cms}}^{-1}$)	9.0	1.5

^aIEC61217 convention.