Authors:
K.-M. Chui1, S. L. Chui2, A. Wojciechowski3, W. Glinkowski3; 1Uxbridge/UK, 2Prince George, BC/CA, 3Warsaw/PL
DOI:
10.1594/ecr2010/C-2935
Purpose
Corrections within the processing software such as the Back-Projection Algorithm (for CT or NM/PET) or the Fast Fourier Transform (for MRI) are unable to overcome or remove the century-old Penumbra Effect. But this effect may be overcome by the following post-processing Computer Aided Detection (CAD) algorithm.
The Penumbra-Effect (refer to Figure 1 (Figure A) for the definition of Penumbra-Spread) due to the size of the energy-source causes blurring at the image edge-profile. A CAD software based on the De-convolution Technique can be used to pinpoint the true-edge positions to sub-pixel accuracy and remove the Penumbra-Effect via sub-pixel transfers without trade-off losses. As both the Penumbra Effect and the Pixelization Effect are overcome at the same time, the overall effect is to literally re-focus the image edge-profile, as if derived from an infinitely small energy source. This is in effect, the perfection of the imperfection of Roentgen's legacy of X-ray radiography since 1895. Subsequently, a definitive method of accurate measurement may have also been found. By solving this previously 'unsolvable' Penumbra problem without any trade-off loss, numerous important applications may now be realized. e.g. enhanced edge-profiles can be used for clearer diagnosis and accurate measurements for some specialized cases. Six field-examples on the studies of fracture bone are used to demonstrate its merits.
Figure 2 (Figure B) & Reference-1 summarize the working principle of the technique.