STATISTICAL METHODS FOR ATTENUATION CORRECTION IN ECT

为了使发射计算机断层扫描（ECT）定量准确， 诊断有效，必须纠正光子的影响 吸收或衰减。 由于人体胸腔内的衰减 不均匀，每个患者的衰减校正因子（ACF）是 通过通常在放射性示踪剂之前的透射扫描计算 注射 用于该计算的常规方法是次优的，并且 因此，透射扫描非常长。 减少 传输扫描时间将大大提高临床实用性 正电子发射断层扫描（PET）。 我们建议开发，实施和调查改进的数据- 显著减少传输扫描时间的处理方法 通过更好地利用传输测量。 到 为了实现这一目标，我们将重点关注惩罚加权最小二乘 （PWLS）方法用于衰减图的统计分割。 通过 使用PWLS分割方法，我们可以直接处理传输 测量，而不是处理中间透射图像 这对于其它方法是必要的。 除了减少注射前透射扫描时间外，我们还将 研究将PWLS方法应用于注射后传输 胸部的测量。 与传统方法不同，PWLS 方法可以容纳由于放射性示踪剂排放的贡献 通过协方差调整。 一种有效的衰减方法 注射后透射测量的校正值为 具有显著的临床价值，特别是对于使用 延迟FDG扫描

For emission computed tomography (ECT) to be quantitatively accurate and diagnostically efficacious, one must correct for the effects of photon absorption or attenuation. Since attenuation within the human thorax is nonuniform, each patient's attenuation correction factors (ACFs) are computed from a transmission scan that usually precedes the radiotracer injection. conventional methods for this computation are suboptimal, and consequently the transmission scans are inordinately long. Reducing the transmission scan time will greatly enhance the clinical utility of positron emission tomography (PET). We propose to develop, implement, and investigate improved data- processing methods that significantly reduce the transmission scan time through better utilization of the transmission measurements. To accomplish this goal, we will focus on penalized, weighted least-squares (PWLS) methods for statistical segmentation of attenuation maps. By using PWLS segmentation methods, we can directly process the transmission measurements, rather than processing an intermediate transmission image as is necessary for other methods. In addition to reducing pre-injection transmission scan time, we will investigate applying the PWLS methods to post-injection transmission measurements of the thorax. Unlike conventional methods, the PWLS methods can accommodate the contributions due to radiotracer emissions through covariance adjustments. An effective method for attenuation correction from post-injection transmission measurements would be of significant clinical value, particularly for PET oncologic imaging using delayed FDG scans.