Table 3.

Depth of dose maximum (d_max) values (cm) in the presence of air gaps between different thicknesses of gel bolus and water surface of radiation field analyzer- (RFA- 300), obtained from central axis depth dose curve of 6 MV clinical photon beam for different field sizes

Bolus thickness (cm)	Field size (cm2)	Air gap (cm)				Shift of “Dmax”*
		0	1.0	2.0	3.0
No bolus	5 × 5	1.4	-	-	-	-
	10 × 10	1.4	-	-	-	-
	15 × 15	1.4	-	-	-	-
	20 × 20	1.2	-	-	-	-
	25 × 25	1.2	-	-	-	-
0.5	5 × 5	1.2	1.2	1.2	1.3	0.1
	10 × 10	1.2	1.2	1.3	1.3	0.1
	15 × 15	1.1	1.1	1.2	1.2	0.1
	20 × 20	1.0	1.0	1.1	1.1	0.1
	25 × 25	0.8	0.9	0.9	1.0	0.2
1.0	5 × 5	0.4	0.4	0.6	0.8	0.4
	10 × 10	0.4	0.4	0.4	0.6	0.2
	15 × 15	0.0	0.4	0.4	0.4	0.4
	20 × 20	0.0	0.2	0.4	0.4	0.4
	25 × 25	0.0	0.2	0.2	0.3	0.3
1.5	5 × 5	0.0	0.2	0.4	0.6	0.6
	10 × 10	0.0	0.2	0.4	0.4	0.4
	15 × 15	0.0	0.2	0.2	0.3	0.3
	20 × 20	0.0	0.2	0.2	0.3	0.3
	25 × 25	0.0	0.2	0.3	0.3	0.3

*Shift of d_max value obtained by subtracting the value of d_max without (0.0 cm) and with (3.0 cm) air gap