Determination of the Absorbed Dose to Water for Medium-Energy X-ray Beams Using Fricke Dosimetry.

PURPOSE For X-ray beams in the low and medium energy range, reference dosimetry is established in terms of air kerma. Fricke dosimetry has shown great potential in the absolute measurements of the absorbed dose to water for high energy ranges. Therefore, the main purpose of this work was to compare the absorbed dose to water for medium-energy X-ray beams obtained through Fricke dosimetry with that obtained from the air kerma rate. METHODS To determine the absorbed dose to water using Fricke dosimetry the polyethylene bags methodology was chosen. Fricke solution was irradiated at four different beam qualities. The absorbed dose to water values obtained using Fricke dosimetry were compared to those obtained using the standard protocol, using the Z-score. RESULTS Values of the Z-score were less than 2 for all measurements of absorbed dose to water, which means that the values obtained using Fricke dosimetry are equivalent to those obtained using the reference protocol. The combined standard uncertainty for the absorbed dose to water obtained by Fricke dosimetry was lower than that obtained with the ionization chamber. CONCLUSION Chemical dosimetry using a standard FeSO4 solution has been demonstrated to be a potential option as a standard for the quantity absorbed dose to water for medium kV X-ray qualities.