A combined PET/CT scanner for clinical oncology.

TLDR

Accurate co‑registration of whole‑body PET and CT images is crucial for diagnosing, staging, and monitoring malignant disease, yet alignment across scanners is difficult outside the brain, prompting the design of a combined PET/CT tomograph that can acquire precisely aligned functional and anatomical images for any body region. The system integrates a Siemens Somatom AR.SP spiral CT with a partial‑ring ECAT ART PET scanner mounted on a common gantry, allowing separate or simultaneous acquisition; in combined mode CT data correct PET for scatter and attenuation, and the device can perform transmission scans with dual 137Cs sources, enabling whole‑body imaging of over 110 patients across multiple cancer types. The combined PET/CT scanner delivers fully quantitative whole‑body images over 100 cm in under an hour, has been successfully operated in a clinical setting, and its first performance measurements and illustrative cancer studies demonstrate its practical effectiveness.

Abstract

The availability of accurately aligned, whole-body anatomical (CT) and functional (PET) images could have a significant impact on diagnosing and staging malignant disease and on identifying and localizing metastases. Computer algorithms to align CT and PET images acquired on different scanners are generally successful for the brain, whereas image alignment in other regions of the body is more problematic.A combined PET/CT tomograph with the unique capability of acquiring accurately aligned functional and anatomical images for any part of the human body has been designed and built. The PET/CT scanner was developed as a combination of a Siemens Somatom AR.SP spiral CT and a partial-ring, rotating ECAT ART PET scanner. All components are mounted on a common rotational support within a single gantry. The PET and CT components can be operated either separately, or in combined mode. In combined mode, the CT images are used to correct the PET data for scatter and attenuation. Fully quantitative whole-body images are obtained for an axial extent of 100 cm in an imaging time of less than 1 h. When operated in PET mode alone, transmission scans are acquired with dual 137Cs sources.The scanner is fully operational and the combined device has been operated successfully in a clinical environment. Over 110 patients have been imaged, covering a range of different cancers, including lung, esophageal, head and neck, melanoma, lymphoma, pancreas, and renal cell. The aligned PET and CT images are used both for diagnosing and staging disease and for evaluating response to therapy. We report the first performance measurements from the scanner and present some illustrative clinical studies acquired in cancer patients.A combined PET and CT scanner is a practical and effective approach to acquiring co-registered anatomical and functional images in a single scanning session.