Figure 3: (a) The PDD curves calculated and measured in 4 cm × 4 cm, 10 cm × 10 cm, and 20 cm × 20 cm field sizes (to avoid overlapping them, PDD values for 4 cm × 4 cm, 10 cm × 10 cm, and 20 cm × 20 cm field sizes have been multiplied by 0.8, 1, and 1.2, respectively). (b) Gamma index values for evaluating the agreement between calculated and measured PDDs in 4 cm × 4 cm, 10 cm × 10 cm, and 20 cm × 20 cm field sizes. PDD: Percentage depth dose