Studies on the computer processing of the radioisotope images, 1

In order to improve the quality of radioisotope (RI) images, several trials of the mathematical data processing of RI images obtained from a scintiscanner and a scinticamera and their clinical application were attempted. Images from the scinticamera were divided into a 40 x 40 matrix and the counts in each element were transferred onto the 7 track digital magnetic tape recorder (TM-7). Pulses from a scanning area of 1 mm length obtained during scanning of the scintiscanner were stored in each channel of the 1600 word memory successively. After the scanning of each line, the data were transferred onto the TM-7. Present data processing involves the followings: data smoothing in order to reduce the statistical fluctuation of the data, image enhancement to improve spatial resolution, correction for spatial distortion of the images and graded image display. Both the iterative approximation (IA) method and the Fourier transform (FT) method were tried and compared in order to improve the spatial resolution of the image. The IA method was superior to the latter in the stability of the reconstructed images. Correction of the field non-uniformity of the scinticamera was performed by multiplying the counts in each element by the correction coefficients obtained from the flat field phantom studies. When the short half-life nuclides were used, images obtained with a scintiscanner might be affected by the decay of the nuclide. However, the true distribution of the radioactivity could be reproduced by correcting the image by a decay factor matched with the scan speed. It was concluded that the computer processing of RI images was clinically useful by significantly improving the details of scan display. (Saito, K.)