Table 1.

Penumbra, amplitude, and planar dose difference of the multileaf collimator (MLC)‐80, MLC‐120, dual‐layer micro‐MLC (DmMLC) and Cerrobend ^a blocks

		80%–20% Isodose line penumbra	50% Isodose line amplitude	Planar dose difference range at field edge ($\pm 2.5\mathrm{\%}$)
Collimation device	Leaf width (mm) at isocenter lever	[mm ($\pm 0.25$ mm)] at 45‐degree angle	[mm ($\pm 0.25$ mm)] at 45‐degree angle	against blocks	against DmMLC
MLC‐80	10	9.0	5.5	$52.5\mathrm{\%}$	$52.5\mathrm{\%}$
MLC‐120	5	5.0	2.0	$35.0\mathrm{\%}$	$35.5\mathrm{\%}$
DmMLC	3.2	3.0	0.5	20.0%	—
Cerrobend block	—	2.0	0	—	—

^aCerro Metal Products, Bellefonte, PA.