| 摘要 |
PURPOSE:To obtain an transmission image of radioactive rays of a material to be inspected having uniform concentration, by keeping the ratio of moving velocity of the radioactive rays passing slit and keeping a dose of radioactivity irradiated to the material to be inspected at a constant value. CONSTITUTION:A radioactive rays sheltering body 9 formed in curved shape is provided between a radioactive rays source 8 and a material to be inspected 7 along a circular arc centering around the source 8. This body 9 is constituted by a pair of lead plates 9a forming a radioactive rays passing slit 11 between the tip ends neighboring each other and the body 9 is moved along the circular arc centering around the source 8 by a motor 19. This moving velocity is detected by a velocity detector 26 connected to an axis of rotation 19a of the motor 19 and a dose of radioactivity during movement of the body 9 is detected by a dose of activity detector 25. The ratio of the detected value of the detector 25 and that of the detector 26 is operated and the moving velocity of the body 9 is controlled so as to eliminate the deviation from the preliminarily determined value and then, irradiating quantity of the radioactive rays to a film 24 is made uniform. |
