Table 1.

Average radiation penumbra (80%–20%) of different HDMLC defined square and circular fields measured at ${\mathrm{d}}_{\text{max}}$ for SRS6, 6, and 10 MV X‐rays.

	Average Penumbra in cm for Square and Circular Fields
	Parallel to Leaf Motion			Perpendicular to Leaf Motion
Field Size $({\mathit{\text{cm}}}^2)$	SRS6 MV	6 MV	10 MV	SRS6 MV	6 MV	10 MV	Circular Field Diameter (cm)	Parallel to Leaf Motion 6 MV
$1\times 1$	0.20	0.27	0.33	0.20	0.24	0.32	1	0.25
$2\times 2$	0.23	0.29	0.41	0.20	0.27	0.38	2	0.30
$3\times 3$	0.23	0.31	0.43	0.19	0.25	0.38	3	0.31
$4\times 4$	0.24	0.33	0.49	0.20	0.27	0.43	4	0.33
$5\times 5$	0.25	0.36	0.52	0.21	0.29	0.43	5	0.34
$10\times 10$	0.26	0.42	0.63	0.21	0.30	0.49	10	0.38
$15\times 15$	0.29	0.47	0.62	0.23	0.34	0.48	15	0.40
$20\times 20$		0.49	0.64		0.36	0.50