| 摘要 |
PURPOSE: To maximize a rate of a signal to a noise by multiplying a difference image by a coefficient corresponding to a way that concentration is changing according to a time as weight, and forming a sum. CONSTITUTION: A series of difference image data before contrasting, difference image data at the time of contrasting, and difference image data after contrasting stored in a video disk 7 are multiplied by each coefficient stored in an ROM 90 by multiplier 96. The coefficient by which the difference mage data at the time of contrasting is multiplied is proportional to the projective intensity of the medicine lump of a contrast medium in a time substantially matched with the difference image at the time of contrasting, and selected one coefficient is applied to a corresponding picture at the time of contrasting including the maximum contrast medium. Also, the coefficients applied to the difference image before contrasting and the difference image after contrasting are selected so that the sum of all the coefficients can be equal to almost zero. Then, a series of results obtained by the multiplication of the difference image data by the coefficients are added, and a set of data indicating the contrast medium in a blood vessel can be generated. Thus, the rate of a signal corresponding to the X-ray contrast medium in the blood vessel to a noise in a blood vessel picture can be increased.
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