| 摘要 |
An X-ray image pick-up device includes an X-ray source for radiating X-rays onto an object including a region of interest, an image intensifier for converting to an optical image an X-ray image obtained when the X-rays radiated from the X-ray source are transmitted through the object, an image pick-up camera for converting to an image pick-up signal the optical image which is generated from the image intensifier, and an optical diaphragm arranged between the image intensifier and the image pick-up camera for adjusting an amount of optical image light incident on the image pick-up camera. The X-ray image pick-up device further includes an exposure controller for detecting both the maximum value of image pick-up signals from the pick-up camera and the average value of the image pick-up signals in the region of interest at a time of fluoroscopic examination, for calculating the density resolutions of the output pick-up signals from the image pick-up camera with respect to the various combinations of tube voltages, tube currents and optical diaphragm values, and for determining a tube voltage and a tube current of an X-ray source, along with an optical diaphragm value so as to provide a maximum density resolution which permits the device to always operate under optimal exposure conditions. |
