| 摘要 |
A tomographic apparatus for constructing a two-dimensional image of a cut through an object comprises a source; a detector opposite to the source; means for causing relative movement between the object and the source-detector combination; reconstruction means coupled to said detector which calculates values of absorbed radiation in each of an arbitrarily large number of voxels. The detector comprises a chamber (13) filled with an ionizable substance, and including a first (17, 18) and a second (27, 29) electrode arrangement, substantially in parallel with each other; a radiation entrance (33) arranged such that the planar radiation beam (1) can enter the chamber between and substantially in parallel with the first and second electrode arrangements and ionize the ionizable substance; an electron avalanche amplification means (15) for avalanche amplification of electrons created during ionization; and a read-out arrangement (27) for detection of the electron avalanches and/or correspondingly produced ions. |
