1977 Volume 26 Issue 8 Pages 541-546
Tumor imaging with 197HgCl2 and the subtraction image with 197HgCl2 and 99mTchuman serum albumin were performed for the diagnosis of lung cancer, using a scintillation camera coupling to a small digital computer. The positional pulses from the scintillation camera were fed into 4096 words memory through materix input controller, and transferred from computer to magnetic tape recorder. The tumor imaging was obtained using 197HgCl2, and patient remaining in the same position was given 99mTc-HSA for subtraction which distributed in blood pool. Matrix images of magnetic tape were fed into the small digital computer and these images were displayed on the graphic display device. The location for subtraction was selected by the cursor on the image of 99mTc-HSA, and this positional information was transferred from the graphic display device to the computer in order to calculate count ratio (subtraction ratio) between the two images. Counts on the matrix image of 99mTc-HSA were multiplied by the subtraction ratio. This normalized image was subtracted from the tumor image. By this procedure, the image quality of the subtraction image was more enhanced than that of the conventional tumor image with 197HgCl2. Especially, it seemed to be valuable for detecting the lesion in the mediastinum and hilar region so that the part of non-specific concentration of 197HgCl2 on the tumor image was erased. These images were displayed as smoothed image with 25 points weighted average in order to eliminate the noise, these images were more useful to enhance the image quality than the smoothed image with 25 points simple average.
