An X-ray digital tomosynthesis system and method

Initial alignment of a tomosynthesis system, in order to correctly image a region of interest, requires skill on the part of the operator, particularly where the region of interest is an internal structure with only limited surface features. It can be tens of seconds, sometimes minutes, to reconstruct an entire 3D tomosynthesis image, and therefore it can take this long before an operator realises that a subsequent scan is required. In this time, the patient may have moved and a second scan could also potentially miss the region of interest, requiring a third scan, and so on. Multiple exposures are not only time-consuming, but also increase the dosage of radiation received by a patient. The present invention provides a digital x-ray tomosynthesis system comprising a static array of x-ray emitters and an x-ray detector and involves selecting a sub-set of x-ray emitters such that no part of the x-ray detector is exposed to x-rays from more than nine of the sub-set and generating a composite image (50) from non-overlapping portions of each of the respective images (52, 53) produced on the x-ray detector. In this way, a two-dimensional image of a subject may be produced using a minimal dosage of radiation.