Thread counting algorithms seek to determine from x-ray images the vertical and horizontal thread counts (frequencies) of the canvas weave comprising a painting's support. Our spectral-based algorithm employs a variant of short-time Fourier analysis to the image domain that reveals isolated peaks at the proper vertical and horizontal frequencies. Paintings made on canvas sections cut from the same canvas roll have been hypothesized to have similar, distinctive weave characteristics, allowing art historians to more accurately date paintings. Spatial variation of weave frequency measurements across a painting were cross-correlated using a new measure to determine possible common weave patterns between pairs of x-rays. By analyzing a database of x-rays made from 180 paintings by van Gogh, our algorithms confirmed situations where paintings were known to have been made on canvases cut from the same roll and found new ones.

A Multiwire Gamma Camera (MWGC) images the generator-produced Ta-178 radiopharmaceutical, which is intravenously injected and utilized as a blood labeling agent. Via this approach, high-quality, first-pass imaging of the human heart is performed to study left ventricular function of patients during peak exercise on a treadmill, as an efficient and cost effective method of assessment of patients presenting with chest pain symptoms. Patient motion and resulting image blurring during the treadmill exercise can degrade resolution and introduce serious image distortion. We have developed a correction method which utilizes an electromagnetic motion tracking system to continuously record the six-dimensional position and orientation of the torso during imaging. Correction is achieved by spatially repositioning imaging data, utilizing the simultaneously acquired six dimensional position data. The method was evaluated in dynamic phantom simulations using an Am-241 point source worn by a volunteer exercising at Bruce Level V. Accuracy of correction was assessed by calculating root mean square (RMS) error of the positions of the maximum activity pixel in uncorrected and corrected images, and by visual comparison of corrected versus uncorrected images. The results show that the motion artifact can be effectively removed with source movement simulating that of a patient's heart at peak exercise. We conclude that this method shows promise to compensate for body motion under clinical MWGC imaging conditions during treadmill exercise.

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