A standard Fricke dosimeter compared to an ionization chamber used for dosimetric characterization of ⁶⁰Co photon beam

The main objective of this study was to investigate the Fricke dosimeter water equivalent system for measurement of dosimetric parameters for photon beam. The parameters measured with the Fricke dosimeter were compared to those obtained with an ionization chamber. In this work characteristics for ⁶⁰Co γ-rays of field sizes ranging from 5 × 5 cm² to 20 × 20 cm² are reported. The measurements were carried out in the secondary standard dosimetry laboratory using a collimated ⁶⁰Co gamma source therapy unit. The ⁶⁰Co beam output in terms of absorbed dose to water was obtained as per IAEA TRS 398 recommendations using cylindrical ionization chamber, whose N_D,w has been supplied by the IAEA's reference laboratory. Specific quantities measured include: output factors, peak scatter factor, lateral beam profiles and percentage depth dose. The Fricke dosimeters were irradiated in a water phantom using the suitable poly (methyl methacrylate), PMMA stand. Our results demonstrate that Fricke dosimeter and ionization chamber agree with each other.