Abstract: A method and apparatus for radiography, and especially for planar beam radiography, and also a detector for detecting incident radiation. In the method and the apparatus, wherein X-rays are emitted from an X-ray source, the X-rays are formed into a planar beam and are transmitted through an object to be imaged, and the X-rays transmitted through said object are detected in a detector. The detector, which detects incident radiation is a gaseous parallel plate avalanche chamber, including electrode arrangements between which a voltage is applied for creating an electrical field, which causes electron-ion avalanches of primary and secondary ionization electrons released by incident radiation. The detector is oriented, in relation to the incident radiation, so that the radiation enters sideways between a first and a second parallel plate, between which the electrical field is created.