A clinical imaging system based upon an amorphous-Silicon (a-Si) flat dynamic (digital) X-ray image detector (FDXD) has been developed. The objectives of this experimental set-up were to determine the physical image quality and to establish the clinical feasibility of a flat-panel X-ray detector for radiography and fluoroscopy (R&F) applications. The FDXD acquires dynamic X-ray images at high frame rates in both continuous and pulsed fluoroscopic modes, lower frame rate exposures and single shots. The system has been installed in a clinical research room at The General Infirmary, Leeds (UK) and is being evaluated in a variety of universal R&F contrast medium aided examinations, including barium swallows, meals and enema examinations. In addition, general radiographic examinations have been performed. Both the established benefits and possible dniwbacks of this type of system, together with the potenthi solutions, are discussed in this paper. Approach, design and set-up of the system are presented, and the dose efficiency and image quality achieved in clinical operation are explained. The technical and medical phantom images have been evaluated and analyzed. The results of the clinical examinations in mixed applications are discussed. The results of the measurements and examinations performed to date on this experimental FDXD system confirm the potential of this new type of digital X-ray image detector.

An evaluation of the physical imaging performance of a prototype CCD-based TV camera (XTV16) cardiac Digital Fluorography system is presented. A tube-based TV camera (XTV1 1) operates in parallel, via a 50% mirror, allowing a direct comparison between the two different TV image recording technologies. The MTF, Noise Power Density (NPD) spectrum and the DQE of the system have been determined. The NPD analysis has been completed in both horizontal and vertical directions and, for completeness, a two dimensional noise analysis of the system has also been carried out. An audit of the main sources of noise in the systems is presented. The effectiveness of image corrections in minimising systematic noise due to the CCD camera is demonstrated. The DQE spectra of both systems at zero frequency are X-ray quantum noise limited and they are both operating dose efficiently. The DQE spectrum in the horizontal direction of the XTV16 at high spatial frequencies is shown to be superior to that of the XTV 1 1 which may translate to improved rendition of small features in clinical images.The CCD camera system described here is now used in the Cardio-Vascular systems of a major european company.

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