摘要 |
In a radiographic apparatus, radiation is projected through a substantially planar region of a body along a plurality of beam paths which are laterally and/or angularly displaced from one another. A detecting arrangement is provided for detecting the radiation emergent from the body along each path. The detecting arrangement comprises a plurality of cells containing a noble gas such as xenon. The radiation is periodically interrupted to allow time for each cell to be scavenged of ions produced by radiation traversing one path before radiation is incident on the same cell from another path. |