Surface and Buildup Region Dose Measurements with Markus Parallel-Plate Ionization Chamber, GafChromic EBT3 Film, and MOSFET Detector for High-Energy Photon Beams

Table 1

(a) Percentage depth doses (PDDs) obtained with a Markus chamber in a water equivalent RW3 phantom using 6 MV photon beams for different field sizes at SSD = 100 cm. (b) Percentage depth doses (PDDs) obtained with a Markus chamber in a water equivalent RW3 phantom using 15 MV photon beams for different field sizes at SSD = 100 cm.

(a)

Phantom depth (mm)	WET (mm)	PDD (%)
		5 × 5 cm^2	10 × 10 cm^2	20 × 20 cm^2
0	0.023	10.8 ± 0.8	16.6 ± 0.9	28.1 ± 0.8
0.067	0.07	14.6 ± 0.9	20.3 ± 0.9	31.4 ± 0.8
1	1.068	38.7 ± 0.8	43.4 ± 0.8	52.5 ± 0.7
2	2.113	57.1 ± 0.7	61.0 ± 0.6	68.2 ± 0.6
5	5.248	83.6 ± 0.6	85.9 ± 0.4	90.0 ± 0.4
10	10.473	97.8 ± 0.2	98.4 ± 0.2	99.2 ± 0.3
15	15.698	100.0 ± 0.1	100.0 ± 0.1	100.0 ± 0.2

(b)

Phantom depth (mm)	WET (mm)	PDD (%)
		5 × 5 cm^2	10 × 10 cm^2	20 × 20 cm^2
0	0.023	6.9 ± 0.9	13.7 ± 0.8	26.7 ± 0.8
0.067	0.07	8.0 ± 0.9	14.9 ± 0.8	27.9 ± 0.8
1	1.068	22.7 ± 0.8	29.6 ± 0.7	42.0 ± 0.8
2	2.113	34.8 ± 0.7	41.5 ± 0.6	53.5 ± 0.9
5	5.248	60.3 ± 0.8	65.8 ± 0.7	75.6 ± 0.8
10	10.473	81.3 ± 0.6	85.4 ± 0.5	92.1 ± 0.6
15	15.698	92.3 ± 0.4	94.8 ± 0.3	98.6 ± 0.4
20	20.923	97.1 ± 0.3	98.7 ± 0.3	101.0 ± 0.9
25	26.148	99.6 ± 0.3	100.1 ± 0.3	100.9 ± 0.7
30	31.373	100.0 ± 0.2	100.0 ± 0.2	100.0 ± 0.3