CHAPTER VI
CONCLUSION
Penumbral widths for field size of 11, 22, and 33 cm2at depths of 1.5, 10, and 20 cm were measured at the small field conditions. Films (EDR2 and EBT2) were used as a reference penumbral width measurement to compare with diodes detectors (PFD, EDGE, and SFD).
EDR2 has slightly energy dependence compared with EBT2 film. It obtained wider penumbral width than EBT2 however there is no significant difference between them. PFD has wider penumbral width when compared with other diodes. EDGE obtain comparable penumbra width and SFD show the thinnest penumbra width. When compare all types of diodes with EBT2 radiochromic film. Over all, the result found that they are different with in ± 0.5mm.
Yin et al mentioned that SFD and the mini-ion-chamberare reliable and suitable for small field dosimetry because their detector sizes are smaller than measured field size larger than 5 mm by using Monte Carlo simulation suggested by Bjarngardet al. Our smallest field size is 11 cm2 therefore our dedicated diodes (SFD and EDGE detectors) are considered the appropriate detectors of choice for penumbral width measurement in our measured small field sizes ranged between 11 and 33 cm2.
All in all, the absolute maximum significant difference is less than 0.5 mm occurred at field size of 33 cm2 and depth of 1.5 cm compared between EBT2 film and SFD detector.