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. (Support: NIH Grants R01EB008425, R01NS43924, R01EB002873)
We report on the technology of imaging corrections for a new solid state x-ray image intensifier (SSXII) with
enhanced resolution and fluoroscopic imaging capabilities, made of a mosaic of modules (tiled-array) each
consisting of CsI(Tl) phosphor coupled using a fiber-optic taper or minifier to an electron multiplier charge
coupled device (EMCCD). Generating high quality images using this EMCCD tiled-array system requires the
determination and correction of the individual EMCCD sub-images with respect to relative rotations and
translations as well as optical distortions due to the fiber optic tapers. The image corrections procedure is
based on comparison of resulting (distorted) images with the known square pattern of a wire mesh phantom.
The mesh crossing point positions in each sub-image are automatically identified. With the crossing points
identified, the mapping between distorted and an undistorted array is determined. For each pixel in a
distorted sub-image, the corresponding location in the corrected sub-image is calculated using bilinear
interpolation. For the rotation corrections between sub-images, the orientation of the vectors between
respective mesh crossing points in the various sub-images are determined and each sub-image is
appropriately rotated with the pixel values again determined using bilinear interpolation. Image translation
corrections are performed using reference structures at known locations. According to our estimations, the
distortion corrections are accurate to within 1%; the rotations are determined to within 0.1 degree, and
translation corrections are accurate to well within 1 pixel. This technology will provide the basis for generating
single composite images from tiled-image configurations of the SSXII regardless of how many modules are
used to form the images.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.