MRI for radiotherapy simulation, planning and/or treatment guidance requires accurate motion assessment and real-time tumor monitoring. Clinical image-guided radiotherapy requires precise quality assurance of targeted tumor geometry and motion phase and amplitudes for both MRI and CT images. In various embodiments, the MRI-CT compatible phantom described herein is designed to validate the accuracy and performance of clinical procedures in both a 4D MRI sequence and 4D CT imaging, and to provide equivalent dynamic image contrast and quality for both imaging modalities. Additionally described is a PET compatible phantom.
