Hasegawa T, Hashiba H, Akagi K, Fujino T, Kobayashi A, Matsuda M
Radioisotopes. 1978 Jun;27(6):311-7. doi: 10.3769/radioisotopes.27.6_311.
High energy collimators in use today are limited with respect to resolution and efficiency. The multiple pinhole coded aperture (hereafter abbreviated as MPCA) is a method being considered to improve the above. In our study we conducted basic experiments with an MPCA using an Anger-type gamma-camera. Using this method, we were able to perform radioisotope imaging and radioisotope tomographic effect. We have studied the resolution, detection efficiency, and tomographic effects of the MPCA. We found that, in the MPCA, detection efficiency is proportional to the number of pinholes and resolution is dependent upon the pinhole diameter. This tomographic effect is of the same principle as the stretching-type tomography, images on both side of the desired image appearing as noise images, affecting the depth resolution. Using an MPCA with a pinhole diameter of 3 mm and 3 pinholes positioned in an equilateral triangular pattern measuring 7.8 cm on each side, we attained a depth resolution of 3 cm. Because the MPCA method involves complicated image processing, the resulting image contains a factor of 2n-2 (where n is the number of pinhole) of noise, affecting the depth resolution.
目前使用的高能准直器在分辨率和效率方面存在局限性。多重针孔编码孔径（以下简称为MPCA）是一种被认为可以改善上述问题的方法。在我们的研究中，我们使用安格型γ相机对MPCA进行了基础实验。通过这种方法，我们能够进行放射性同位素成像和放射性同位素断层成像效果研究。我们研究了MPCA的分辨率、探测效率和断层成像效果。我们发现，在MPCA中，探测效率与针孔数量成正比，分辨率取决于针孔直径。这种断层成像效果与拉伸型断层成像原理相同，所需图像两侧的图像会呈现为噪声图像，影响深度分辨率。使用针孔直径为3毫米、3个针孔呈等边三角形排列且每条边长7.8厘米的MPCA，我们获得了3厘米的深度分辨率。由于MPCA方法涉及复杂的图像处理，生成的图像包含2的n - 2次方（其中n是针孔数量）的噪声因子，影响深度分辨率。
