Cao Z, Tsui B M
Department of Biomedical Engineering, University of North Carolina, Chapel Hill 27599.
Med Phys. 1992 Sep-Oct;19(5):1205-12. doi: 10.1118/1.596752.
Transmission imaging is receiving increasing attention in SPECT due to the need to compensate for nonuniform attenuation in cardiac-chest SPECT. The quality of a transmission image has an important effect on the measured attenuation distribution. To improve image quality, knowledge of the performance characteristics of a transmission imaging system is essential. The characteristics, spatial resolution, detection efficiency, photon flux, and exposure to the object, of a transmission imaging system consisting of a gamma camera and a uniform sheet source have been studied. The results demonstrate that spatial resolution of a transmission imaging system can be improved by use of a high-resolution source collimator at the price of a moderate decrease in detection efficiency, in comparison to the uncollimated case. Also, the source collimator significantly reduces the photon flux and exposure to the object. This investigation suggests that a high-resolution collimator be used with an intense sheet source to improve spatial resolution and reduce statistical noise with low exposure to the patient. This research further suggests that the amount of source activity is determined by the requirement of image quality, detection geometry, and allowed absorbed dose to the patient.
由于需要补偿心脏胸部单光子发射计算机断层显像（SPECT）中的非均匀衰减，发射成像在SPECT中受到越来越多的关注。发射图像的质量对测量的衰减分布有重要影响。为了提高图像质量，了解发射成像系统的性能特征至关重要。已经研究了由伽马相机和均匀片状源组成的发射成像系统的特征、空间分辨率、探测效率、光子通量以及对物体的照射。结果表明，与无准直情况相比，使用高分辨率源准直器可以提高发射成像系统的空间分辨率，但代价是探测效率适度降低。此外，源准直器显著降低了光子通量和对物体的照射。这项研究表明，应将高分辨率准直器与强片状源一起使用，以提高空间分辨率并在低患者照射情况下降低统计噪声。这项研究进一步表明，源活度的量由图像质量要求、探测几何形状以及允许的患者吸收剂量决定。
