A method of tomographic imaging using a multiple pinhole-coded aperture.

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.