| 摘要 |
PURPOSE: To decease cumulative exposure of a living body to X-rays by observing shadow of the X-rays of the living body for a specified period in frame scanning period by a fluorescent through-view camera and catching the frame of an image sample by a frame filling device. CONSTITUTION: A gate-type X-rays source 11 has a collimeter 12 and a human body 13 on a table being transparent to X-rays irradiation is irradiated with X-rays. The X-rays passes through the table 14, the human body 13, a grid 15 and an image intensifier tube 16 but a screen made of a phosphorescent material, etc., exist in the tube 16 and light is emitted. The image of the shadow of the X-rays of irradiated part of the human body 13 in this emitted light is focused a photosensitive screen of a video camera 18 by an optical system. To avoid coma, duration of the emitted light from the screen, etc., of the phosphorescent material in the tube 16 is shorter than a frame scanning period. In addition, X-rays source 11 is pulse-driven and is made to get the gate so as to feed beams of X-rays irradiation during a shorter duration time than the frame scanning time. |
