This dataset includes scans of a dynamic anthropomorphic thorax phantom, acquired on both 4D Computed Tomography (4DCT, Siemens SOMATOM Definition Drive CT scanner, Siemens Healthineers AG, Forcheim, Germany) and Cone Beam Computed Tomography (CBCT, Varian Halcyon equipped with HyperSight, Varian Medical Systems, Inc. Palo Alto, CA, USA). The scans were performed for different patient-specific breathing traces, acquired with the RPM Respiratory Gating System (Varian Medical Systems, Inc. Palo Alto, CA, USA).