METHODOLOGY FOR ONCOLOGY IMAGING WITH A PET/CT SCANNER

我们最近开发了一种PET和CT联合扫描仪，它可以 首次允许获取配准的CT和PET图像 在单个设备中按顺序排列，克服了由于内部 器官运动、扫描仪床面的变化以及患者的体位 进行扫描。PET/CT结合了西门子Somtom AR.SP螺旋CT扫描仪 配有旋转的EVAT ART PET扫描仪。到目前为止，PET/CT扫描仪已经使用 对60多名癌症患者进行研究。这一竞争性延续的目标是 是扩展基于CT的衰减的开发和验证 校正并执行新的采集和图像重建 涉及患者床位持续运动的程序。 为了获得良好的信噪比(SNR)来成像 正文中，提出了既要改进基于CT的衰减校正 程序和PET发射扫描中噪声结构的均匀性。 基于CT的衰减校正提供了几乎无噪声的校正因子。 然而，基于CT的衰减在许多方面已经出现 校正率可能会有显著的提高。这些措施包括核算 呼吸运动、截断CT视野、波束的影响 硬化和静脉注射造影剂。此外，对 将通过比较重建的发射扫描来执行基于CT的校正 利用基于CT的因子重建得到的因子的图像 来自标准的PET传输扫描。为此，PET/CT扫描仪是 配备在单人模式下工作的准直铯点源。 通过实施连续床，还可以进一步提高SNR 用于PET发射扫描的运动采集。这样的方法避免了 需要获取可导致轴向变化的SNR和 整体效率较低。连续床面运动的一个特点是使用 列表模式数据采集，这也提供了直接 在扫描过程中纠正病人的移动。建议中的发展 方法学将进一步提高PET/CT研究的图像质量。

We have recently developed a combined PET and CT scanner which allows, for the first time, registered CT and PET images to be acquired sequentially in a single device, overcoming alignment problems due to internal organ movement, variations in scanner bed profile, and positing of the patient for the scan. The PET/CT combines a Siemens Somatom AR.SP spiral CT scanner with a rotating EVAT ART PET scanner. To date, the PET/CT scanner has been used to study over sixty cancer patients. The aims of this competitive continuation are to extend the development and validation of the CT-based attenuation correction and to implement a new acquisition and image reconstruction procedures involving continuous patient bed motion. In order to achieve good signal-to-noise (SNR) for imaging any region of the body, it is proposed to improve both the CT-based attenuation correction procedure and the uniformity of the noise structure in the PET emission scan. CT-based attenuation correction provides almost noiseless correction factors. However, a number of aspects have emerged in which CT-based attenuation correction could be significantly improved. These include accounting for the effects of respiratory motion, truncation of the CT field-of-view, beam hardening, and intravenous contrast agents. In addition, validation of the CT-based correction will be performed by comparing emission scans reconstructed with CT-based factors to emission images reconstructed with factors obtained from standard PET transmission scans. For this purpose, the PET/CT scanner is equipped with collimated cesium point sources operating in singles mode. Further improvement in SNR can also be achieved by implementing continuous bed motion acquisition for the PET emission scan. Such an approach obviates the need to acquire overlapping bed positions that lead to axially varying SNR and lower overall efficiency. A feature of continuous bed motion will be the use of list mode data acquisition, which also offers the possibility of directly correcting for patient movement during the scan. The proposed developments in methodology will further improve the image quality of PET/CT studies.