5.1.2.2. Measurement of penumbral width using GafChromic®EBT2 film
The lowest penumbral width is 2.19 mm obtained at depth of 1.5 cm and field size of 11 cm2 and the highest one is 3.09 mm showed at depth of 20 cm and field size of 33 cm2and the maximum SD appears at depth of 20 cm and field size of 33 cm2as presented in Table 5.1.4. The penumbral width increase when depths and field sizes increase. In Figure 5.1.3 (a), at field size of 11 cm2, when depth increases, the penumbral width goes up slightly. In contrast, at field size of 33 cm2, penumbral width rises sharply when depth increases. At the same observation, in Figure 5.1.3 (b), the penumbral width has small changes when field size increases at depth of 1.5 cm but it alters substantially when field size increases at depth of 20 cm. Moreover theincreasing gradient of penumbral width is the same for both in Figure 5.1.3 (a) and (b).