| 摘要 |
PURPOSE:To prevent improper exposure such for example as over exposure caused by covering a measuring field with a negative contrast medium by employing a correction signal or a reference correction signal as a control signal for an automatic exposure control system. CONSTITUTION:In case a specific portion is covered with a negative contrast medium, an output from a light quantity detection element 12 is reduced, whereby an automatic X-ray exposure control circuit 16 and an X-ray controller 17 are actuated, and thereby conditions of X-rays bombarded from an X-ray generator 8 are increased. The conditions are delivered to a switching control means 32 as a fluoroscopic X-ray signal having conditions more than a prescribed value. An AND circuit 44 of the switching means 32 incorporates a division size signal, an fluoroscopic X-ray condition signal, and a standing/falling angle signal respectively via interface circuits 41-43, takes a logical product among these signals, and delivers the result to the switching means 46 as a switching signal. The switching means 46 is operated by the switching signal, whereby the reference correction signal from the reference correction signal generating means 45 is delivered as a control signal to the automatic exposure circuit 16. |
