| 摘要 |
PURPOSE:To find the place where a compensating filter is inserted for a wide- contrast object by connecting additionally a video level indicator which consists of a peak holding circuit and a display device for a peak value to a video signal path. CONSTITUTION:An operator presses the ''test exposure'' button on the panel surface of a video processor 12 before original blood-vessel hematopoietics photographing after an examination position of an object is put in the visual field of an image intensifier by X-ray fluoroscopy. Then, a system controller 14 indicates X-ray exposure in a specific frame period to the video processor 12. Then, a TV camera 10 outputs the video signal corresponding to the object image and its is branched and inputted to a video level indicator 32. The peak holding circuit 34 has a time constant set so that it does not sense too steep a peak. Then, the operator determines optimum photographic condition by selecting a display value which is smaller than maximum values of an A/D converter 18 and a camera and yet sufficiently large. |
