Apparatus for x-ray computer tomography scanning of an object comprising an x-ray generator 1 mounted on a first support 3, an x-ray detector 2 mounted on a second support 10 and a drive mechanism 7 arranged to move the first support 3 along a first annular path 4 and the second support 10 along a second annular path 11. The first and second annular paths are concentric and the diameter of the first annular path is greater than the diameter of the second annular path. The first and second supports 3, 10 are positioned diametrically opposite each other. The drive mechanism 7 is arranged to move the first and second supports 3, 10 at substantially the same angular speed in the same direction so that x-ray radiation emitted by the x-ray generator is directed towards the x-ray detector 2 whilst the first and second supports 3, 10, are moving along the respective first and second annular paths.
