Comparison of IAEA absorbed dose protocols TRS 277 and TRS 398 for different photon energies

OBJECTIVES: In this study, calculation of absorbed doses according to three different IAEA protocols for Co-60, 6 MV, 25 MV photon energies are compared. METHODS: Absorbed dose measurements are made at SSD=SAD distance, 10x10 cm field size and referance depth. Photon energies are measured with five different cylindirical chambers. Polarity and recombination effects are measured for all ionization chambers and energies. RESULTS: After the measurements, calculations are made according to two different protocols and absorbe dose calculated according to TRS 398 protocol is maximum 0.32% bigger than TRS 277’s dose for Co-60, and 0.57% bigger for 6 MV and 1.53% bigger for 25 MV. CONCLUSION: As a result, TRS 398 protocol enables us to calculate much more accurate absorbe dose.