CT AND MRI: A UNIQUE PHANTOM FOR QUALITY CONTROLS

Introduction: Computed tomography (CT) and magnetic resonance imaging (MRI) are highly sophisticated imaging modalities, based on acquisition and correct evaluation of high-resolution images. To guarantee the maintenance of consistent image quality over the lifetime of the radiological equipment, it is necessary to establish and actively maintain regular and adequate quality-assurance (QA) procedures, including quality control tests (QCs), playing a key role within the QA procedure because they enable complete evaluation of system status and image quality. To perform QCs it is necessary to use dedicated phantoms, often one for each image parameter. These phantoms are different in CT and MRI and require a specific QC protocol for each diagnostic device. To simplify and provide a versatile and unique procedure we developed a phantom, which can be used indifferently on both CT and MRI scanners. Materials and Methods: The new phantom consists of a polymethyl methacrylate (PMMA) empty box of parallelepiped form. It is divided into three sections, each of them is dedicated to the measurement of one or more parameters of QCs. The sections can be filled with distilled water, during TC measurements, and for MRI assessment, water could be replaced with a MRI liquid solution. The phantom images were acquired using standard head and body protocols for each devices, and then processed to obtain QC parameters. Results: The obtained images were compared with those acquired using traditional phantoms proposed and produced by professional groups (AAPM, NEMA). The reliability of this innovative phantom was evaluated with respect to previously validated procedures by conducting statistical analysis. Conclusions: In all cases there was no statistically significant variation between the QCs performed by the proposed phantom and those obtained the numerous traditional phantoms. In this manner, Medical Physicists can use only one phantom and one protocol, both in CT and MRI, to conduct QCs.