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The potential performance of the complete system and issues related to sensitivity, spatial resolution, noise, and speed are discussed. The operation and practical implementation of the XLV system are described. The image formation is based on controlled modulation of light from an external source. Subsequently, it is digitized by a scanned optical imager. This causes a change in the optical properties of the liquid-crystal cell and a visible image is generated. Upon exposure to x rays, charge is collected on the surface of the photoconductor. This is a potentially high-quality digital x-ray detector made of a photoconducting layer and a liquid-crystal cell, physically coupled in a sandwich structure. A novel potentially low-cost radiographic imaging system based on established technologies is proposed-the X-Ray Light Valve (XLV). Hence, there is a need for a low-cost digital imaging system for general applications in radiology. However, these imagers are extraordinarily expensive compared to the systems they are replacing. New x-ray radiographic systems based on large-area flat-panel technology have revolutionized our capability to produce digital x-ray images. Webster, Christie Ann Koprinarov, Ivaylo Germann, Stephen Rowlands, J A The x-ray light valve: a potentially low-cost, digital radiographic imaging system-concept and implementation considerations. However, even with this limitation the XLV system is able to meet or exceed the resolution requirements for chest radiography. The Modulation Transfer Function was measured and the limiting factor was seen to be the optical scanner. A prototype XLV was made and a typical office scanner was used for image digitization. Due to the close electrostatic coupling in the XLV, it can be expected that the spatial resolution of this system will also be very high. Both a-Se and LC cells have both been shown separately to have inherently very high spatial resolution.

Here we investigate the spatial resolution possible with XLV systems. The XLV concept combines three well-established and hence lowcost technologies: an amorphous selenium (a-Se) layer to convert x-rays to image charge, a liquid crystal (LC) cell as an analog display, and an optical scanner for image digitization. The XLV has the potential to achieve the immediate readout in an integrated system with image quality comparable to AMFPIs. We have identified a new approach - the X-ray Light Valve (XLV). These approaches suffer from either high cost or high mechanical complexity and do not have the image quality of AMFPIs. Different approaches have been considered to make lower cost, integrated x-ray imaging devices for digital radiography, including: scanned projection x-ray, an integrated approach based on computed radiography technology and optically demagnified x-ray screen/CCD systems. Thus there is a need for a low cost digital imaging system for general applications in radiology. However, these active matrix flat panel imagers (AMFPIs) are extraordinarily expensive compared to the systems they are replacing. In recent years, new x-ray radiographic systems based on large area flat panel technology have revolutionized our capability to produce digital x-ray radiographic images. The x-ray light valve: a low-cost, digital radiographic imaging system-spatial resolution Increasing the detection efficiency to enhance radiographic imaging capabilities is equally effective as increasing the x-ray source yield, e.g., by amore » larger drive laser energy.« less

Electron-photon transport simulations of the interaction processes in the detector reproduce the observed contrast improvement. We attribute this to the higher quantum efficiency of the combined detectors, leading to a reduced photon noise. Used to record x-ray radiographic images produced by an intense-laser driven hard x-ray backlighter source, the IP stacks resulted in a significant improvement of the radiograph density resolution. We demonstrate that stacking several imaging plates (IPs) constitutes an easy method to increase hard x-ray detection efficiency. Improvement of density resolution in short-pulse hard x-ray radiographic imaging using detector stacks