Different size of an image influences the quality of the image. With regard to this subject, basic experimental studies were carried out, and the following results were obtained ; 1) The effect of the minification of the radionuclide image was well appreciated at 500 and 2,000 counts/cm^2 of the background (count density). In addition, it appeared to be the best to take image as 1/6 of the life size and to obtain 6 flames on an 8"×10" film in practical use (Format 6 on an 8"×10" film). 2) The effect minimizing the image was not appreciated at 10,000 counts/cm^2 of the background. In general, the background is usually in yields of 1,000 to 3,000 counts/cm^2 at the routine imaging in Nuclear Medicine, since the routine study has to be as short in time as possible in a busy department and the given dose of the radiopharmaceuticals is limited in clinical use. Therefor, it is desirable to obtain Format 6 on an 8"×10" film.
