Flash computed tomography results using LANSCE and various X-ray sources with amorphous silion detector arrays

摘要

The use of the EG& G-Heimann RTM 128 (1) or dpiX FS20 (2) amorphous silcon (a-Si) detector array for thermal neutron radiography/computed tomography has proven to be a quick and efficient measns of producing high quality digital radiographic images (3). The resolution, although not as good as film, is about 750 mu m with the RTM and 127 mu m with the dpiX array with a dynamic range in exess of 2000. In many respoects using an amotphsu silicon detector is an improvement over other techniques such as imaging with a CCD camera, using a storage phosphor plate or film radiography. Unlik,e a CCD camera, which is highly susceptible to radiation damage, a-Si detectors can be placed in the beam directly behind the object under examination and do not require any special optics of turning mirrors. The amorphous silicon detector also allows enough data to be acquired to construct a digital image in just a few seconds (minimum gate time 40 ms) whereas film or stoage plate exposures can take many minutes and need to be digitized with a scanner. The flat panel can, therefore, acquire a complete 3D computed tomography data set in just a few tens of minutes. While a-Si detectors have been proposed for use with high energy x-ray sources and neutron sources (3,4), to our knowledge, this is the first reported implementation of such a detector at energies of up to 20 MV.