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SU-E-I-113: Alignment and Assembly of Small Field of View Pre-Clinical Images Taken with a Micro-Solid State X-Ray Imaging Detector.

PURPOSE
We have developed a Micro-Solid State X-ray Imaging Intensifier (μSSXII) detector with an electron multiplying (EM)CCD chip which allows for an ultra-high pixel resolution of 8 × 8 microns. However, the EMCCD chip area of 1004 × 1002 pixels results in an 8.032 × 8.016 mm imaging area and restricts the ability of the user to orient and properly image larger pre-clinical objects such as rat-kidney-vasculature casts. We propose a method to align and assemble images of such larger structures while preserving the ultra-high spatial resolution of the μSSXII.


METHODS
An imaging platform of negligible attenuation was attached to a stepper motor giving the platform free movement in the plane normal to the fluoroscopic x-ray beam. By alternating the detector's image acquisition and the stepper movement, many adjacent overlapping views of the object are acquired. The user then identifies the two pixel coordinates in adjacent images which represent the same point in space. A custom Matlab computer code uses the pixel coordinates to aggregate and average the input images which results in a larger field of view consisting of many ultra-high resolution images.


RESULTS
The images were able to be successfully combined to form a large image while preserving the ultra-high resolution of the detector. In experimental tests, multiple portions of a mammography test object were imaged and virtually no spatial resolution degradation was found in the combined image. Additionally, when imaging a resin cast of rat-kidney-vasculature, vessels of less than 50 μm could be viewed in the combined image.


CONCLUSIONS
The setup and method were found to preserve the ultra-high resolution inherent to the μSSXII while allowing pre-clinical imaging of objects larger than the detector's field of view. The large field of view was effective in orienting the user towards specific areas of interest in the objects imaged. Supported in part by: NIH Grants R01-EB008425, R01-EB002873, and an equipment grant from Toshiba Medical Systems Corp.