SU‐E‐I‐48: Noise Reduction with Over‐Sampling for High Resolution Detectors Using a Spread Function Convolution Method

Purpose: A method to reduce noise resulting from the use of higher resolution x‐ray detectors being developed to meet the demands of image guided vascular interventions is demonstrated. Methods: New direct detectors based on amorphous Se can have MTFs that remain high even at their Nyquist frequency. Since such detectors can be made with smaller pixels than may be required for even the high resolution requirements of many neurovascular applications, the resulting over‐sampled images can be convolved with various functions to lower the noise. The effect on resolution can then be compared with a simple pixel binning. The general method proposed by Cunningham et al as the apodized‐aperture pixel (AAP) design was compared with the Result for various simple 1D convolution spread functions with the effects on total noise and MTF compared to that of the binning case for a 25 μm aSe CMOS detector's MTF published by the University of Waterloo group lead by KS Karim. Results: Assuming a white noise image, various convolution kernels resulted in similar reductions of total standard deviation. Detailed comparisons were made with the simple the 2x binning case. While reducing noise, the over‐sampling convolution method using simple convolution low pass filters did not show advantage over 2x binning with regard to modifying the MTF; however, significant improvement was evidenced for the more complex sinc function used in the AAP design. Conclusion: As higher resolution detectors are being developed to meet the increasing demands for improved images to guide finer vascular interventions, use of super‐sampled aSe detectors where resolution is maintained with reduced noise may well fill this requirement. Partial support from NIH Grant R01EB002873 and Toshiba Medical Systems Equipment Grant