An X-ray inspection system for scanning objects is provided. The system includes a stationary X-ray source made of one or more linear modules positioned around a scanning volume, and defining sparsely positioned multiple stationary X-ray source points from which X-rays can be directed through the scanning volume. An X-ray detector array extends around the scanning volume and is arranged to detect X-rays from the source points which have passed through the scanning volume. A conveyor is arranged to convey the objects through the scanning volume and at least one processor processes the detected X-rays to produce three dimensional images of the items.