Maeda H, Takeda K, Matsumura K, Nakagawa T, Kitano T, Ejiri K, Kondou T, Takeuchi A, Toyama H, Takeshita G
Department of Radiological Technology, Fujita Health University School of Hygiene.
Kaku Igaku. 1991 Jan;28(1):27-34.
Image quality of dynamic single photon emission computed tomography (SPECT) using a rotating gamma camera is dependent on the time activity variation of the tracer such as accumulation and excretion in the object's organ. Especially at the early time after injection of radionuclide, artifacts may occur strongly in the SPECT images. Simulated and experimental projection data of line sources and Jaszczak phantom were altered by sequentially weighting the projections with a function that varied linearly with time. With a variation of object activity given by linearly decaying functions, the main effect observed on the SPECT images obtained from simulated line sources was an elliptical deformation on the object. If the changing rate (R (t + 1)-R(t))/R(t) x 100 remained within 20% during acquisition, this deformation of SPECT images of line sources was not noticeable visually and resolution (FWHM) of line sources scarcely was degraded. In renal dynamic SPECT study using 99mTc-DTPA, the image quality of the first scan (30 sec) was considerably degraded. However, the changing rates after the third scan were less than 20% on the mean of 10 kidneys and the image quality was not noticeable visually.
使用旋转伽马相机的动态单光子发射计算机断层扫描（SPECT）的图像质量取决于示踪剂的时间活性变化，例如在物体器官中的积聚和排泄。特别是在注射放射性核素后的早期，SPECT图像中可能会强烈出现伪影。通过用随时间线性变化的函数依次对投影进行加权，改变了线源和贾斯扎克体模的模拟和实验投影数据。对于由线性衰减函数给出的物体活性变化，从模拟线源获得的SPECT图像上观察到的主要影响是物体上的椭圆形变形。如果在采集过程中变化率（R（t + 1）-R（t））/R（t）×100保持在20%以内，线源SPECT图像的这种变形在视觉上并不明显，并且线源的分辨率（半高宽）几乎没有降低。在使用99mTc-DTPA的肾脏动态SPECT研究中，第一次扫描（30秒）的图像质量明显下降。然而，在10个肾脏的平均值上，第三次扫描后的变化率小于20%，并且图像质量在视觉上并不明显。
