Table 2.

Average radiation penumbra (80%–20%) width of $1\times 20\hspace{0.17em}{\text{cm}}^2$ field measured at different off‐axis distances for 6 MV X‐rays at 1.5 cm and 10 cm depth.

	Average Beam Penumbra (SD) in cm at Off‐axis Distances
Depth of Measurement	0 cm	4 cm	8 cm	12 cm
1.5 cm	0.17 (0.01)	0.16 (0.01)	0.16 (0.01)	0.16 (0.01)
10 cm	0.37 (0.03)	0.39 (0.04)	0.38 (0.03)	0.38 (0.03)