| 摘要 |
PURPOSE:To capture the timing immediately before appearance of contrast medium and facilitate to start a hold operation of a maximum and minimum values from that timing by providing a frame memory to hold the maximum and minimum values of each picture element of a video signal of a radiant ray transparent image, and an operating means to be operated when it is judged that the contrast medium has come to visual field. CONSTITUTION:The maximum value of before one period is stored in the frame memory 17. Subtraction of a minimum value hold image of current period from a maximum value hold image of before one period is done in a subtracter 41. It is output through an enhancement circuit 42 and D/A converter 43. When the contrast medium reaches the visual field, through it is not take in the maximum value hold image, its image appears in the minimum value hold image. An observer can see the fact that the contrast medium reached the visual field finally after its image has grown gradually, and can press a button at that time.
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