| abstract |
An imaging device for scan-imaging radiation includes an array (3, fig.1) of detector cells 11 such as Active Pixel Imaging Device (ASID) cells or a Photon Counting Device (PCD) cells which generate charge in response to radiation incident directly upon them (e.g. X-, alpha-, beta- or gamma-rays). In an embodiment of the invention, charge is accumulated in a cell circuit, e.g. 12, associated with each individual detector cell 11. The cell circuits, 12 etc, are controlled so as to allow the accumulated charge from any one cell, e.g. 48 or 12, to be transferred to an adjacent cell, e.g. 12 or 49. By separating the accumulation and the transfer of charge into a first and a second stage, 21 and 22 respectively, each cell circuit is able to continue receiving charge from its associated detector cell 11 while transferring a previously accumulated charge packet and receiving another. Any charge accumulated during that stage is added to the charge received form the adjacent pixel circuit. Thus the device is permitted to continue receiving radiation generated charge from the cells 11 while performing time-delay and integration (TDI) of the accumulated charge. An image of an object (2) is reconstructed in a control electronics unit (4) and displayed on display a screen (5). In another embodiment using PCD methods, photon counts are accumulated in TDI mode rather than charge. |