| 摘要 |
<p>A multi-zoned x-ray exposure detector for a scanning fan beam x-ray system comprises an electron emitter (64) which upon exposure to x-rays (22) emits electrons into a channel defined by isolation walls (48). The channel contains air which is ionized. The isolation walls (48) extend parallel to the direction of the sweeping fan beam behind the electron emitter. Within each channel formed by the isolation walls, is a collection electrode (52) biased in voltage with respect to the electron emitter to collect the ions. The intersection of the beam and the channel defines a zone in which exposure may be determined. The current from the collection electrode is amplified by an amplifier (44) to produce a signal related to x-ray exposure of each zone.</p> |
