The new Solid State X-ray Image Intensifier (SSXII) is being designed based on a modular imaging array of Electron Multiplying Charge Couple Devices (EMCCD). Each of the detector modules consists of a CsI(Tl) phosphor coupled to a fiber-optic plate, a fiber-optic taper (FOT), and an EMCCD sensor with its electronics. During the optical coupling and alignment of the modules into an array form, small orientation misalignments, such as rotation and translation of the EMCCD sensors, are expected. In addition, barrel distortion will result from the FOTs. Correction algorithms have been developed by our group for all the above artifacts. However, it is critical for the system's performance to correct these artifacts in real-time (30 fps). To achieve this, we will use two-dimensional Look-Up-Tables (LUT) (each for x and y coordinates), which map the corrected pixel locations to the acquired-image pixel locations. To evaluate the feasibility of this approach, this process is simulated making use of parallel coding techniques to allow real-time distortion corrections for up to sixteen modules when a standard quad processor is used. The results of this simulation confirm that tiled field-of-views (FOV) comparable with those of flat panel detectors can be generated in ~17 ms (>30 fps). The increased FOV enabled through correction of tiled images, combined with the EMCCD characteristics of low noise, negligible lag and high sensitivity, should make possible the practical use of the SSXII with substantial advantages over conventional clinical systems.

Purpose: Present the design for the new SSXII high‐resolution fluoroscope capable of overcoming lag, noise, and resolution limitations of current flat‐panel devices (FPDs). Method and Materials: The SSXII consists of an array of modules each featuring an electron multiplying (EM) CCD which views a structured phosphor through a fiber‐optic taper (FOT). The EMCCD operates like a standard frame‐transfer CCD; however, an additional row of multiplication elements enables on‐chip signal gains up to 2000X to overcome subsequent instrumentation‐noise degradation. The SSXII therefore has quantum‐limited performance at both fluoroscopic exposures with moderate gain, and radiographic exposures with low gain. The SSXII array design, through pixel binning and module selection, will enable rapid sequence and fluoroscopic imaging for either the full field‐of‐view (FOV) or high‐resolution regions‐of‐interest (ROIs). Results: A SSXII module was assembled with direct fiber‐optic coupling of the 350 micron thick CsI(Tl) phosphor and the EMCCD (Texas Instruments TC285SPD chip with 1004×1002 pixels). Operation at fluoroscopic and angiographic exposure levels was verified experimentally for gains of ∼80X and 1X, respectively, demonstrating sequences of a moving stent with no lag and bar‐pattern resolution up to 20 1p/mm with a 1:1 FOT. An array of four modules each with 6:1 FOTs will have an effective pixel size of 48 microns covering a FOV of 10×10 cm, sufficient for region‐of‐interest and neurovascular imaging. Larger arrays may be constructed to satisfy both cardiac imaging and general fluoroscopic applications. Module alignment, digital stitching, and distortion correction issues are being addressed. Conclusion: When assembled in an array of sufficient size, the new SSXII can be used in the same applications as current FPD's with advantages of high frame rates with no lag, high resolution due to the smaller pixels possible, and low‐effective‐noise, quantum‐limited fluoroscopic performance due to the on‐chip gain.(Support: UB Foundation, NIH grants R01‐EB002873, R01‐NS43924).