Survey of the CT-TO-ED curve for CBCT

In order to take advantage of Cone-Beam Computed Tomography (CBCT) used in IGRT for estimating the dose delivered to patients, it was studied a way of converting CBCT values into ED of a kV-CBCT Elekta XVI System by using the CatPhan® - a simulator object with known densities. It was obtained HU values with differences up to 36.7% when changing the CBCT image acquisition parameters, making the establishment of protocols a fundamental step. Although the applied method was validated with percentage deviations of less than 0.23%, even higher differences were observed in between the curves of the reference CT and CBCT, highlighting the need of studying correction strategies before its implementation in routine. (author)