Improved Scatter Correction for X-ray Conebeam CT Using Primary Modulation

摘要

Recently, we proposed a scatter correction method for x-ray imaging using primary modulation. A primary modulator with spatially variant attenuating materials is inserted between the x-ray source and the object to make the scatter and part of the primary distributions strongly separate in the Fourier domain. Linear filtering and demodulation techniques suffice to extract and correct the scatter for this modified system. The method has been verified by computer simulations and preliminary experimental results on a simple object. In this work, we improve performance by using a new primary modulator with a higher modulation frequency and by refining the algorithm. The improved method is evaluated experimentally using a pelvis phantom. The imaging parameters are chosen to match the Varian Acuity CT simulator, where scatter correction has been shown to be challenging due to complicated artifact patterns. The results using our approach are compared with those without scatter correction, and with scatter estimated and corrected using a slit measurement as a pre-scan. The comparison shows that the primary modulation method greatly reduces the scatter artifacts and improves image contrast. Using only one single scan, this method achieves CT HU accuracy comparable to that obtained using a slit measurement as a pre-scan.