Low dose imaging of technical and biological objects using ultrashort X-ray pulses and photon counting chip

Abstract

Summary form only received as follows: A system is described which is capable of low dose imaging of technical and biological objects using X-ray pulses of /spl sim/200 ps duration in the energy range 10-80 keV. The X-ray pulses are produced by a novel table-top electron and X-ray source (called CIBER-X) pumped by a mode-locked Nd:YAG laser with a 5th harmonic generator. The source provides an X-ray flux of /spl sim/900 photon msrad-1 per pulse and its dimensions are less than 1' 0.25 mm/sup 2/. To keep the X-ray dose as low as possible and improve the contrast resolution the authors use a single photon counting pixel detector as an imaging device. This hybrid semiconductor pixel detector system uses the Photon Counting Chip (PCC) which was developed in the framework of the Medipix Collaboration. The shutter of the pixel system can be synchronized with the pulsing of the laser so that each pulsed image can be read out individually. This means that the dose can be finely tuned to the object which has to be imaged. All of the photons which fall above the detection threshold of the chip are counted. Further details on the authors' set-up for X-ray imaging and several image examples are given. Future improvements and applications of this system are then discussed.