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8 May 1995 Combined SPECT and x-ray CT medical imaging system
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We have designed and built a system for correlated x ray CT transmission and SPECT emission imaging with an array of photon counting detectors. The scanner operates in a third generation fan beam geometry by translating a 23 element high purity germanium detector across the fan to image phantoms and small animals. The x ray CT image is used to obtain an object specific, i.e., anatomically accurate, attenuation map for the reconstruction of the SPECT image. SPECT images are reconstructed with an MLEM code and the pixel values are scaled in physical units by determining a scaling factor from a uniform water phantom with homogeneous and known attenuation. Single myocardial slices of several pigs were imaged with a 99mTc sestamibi imaging agent which is taken up in proportion to regional myocardial blood flow. The results show that 99mTc uptake and regional myocardial blood flow, determined in vivo from reconstructed SPECT images, correlate with the measured in vitro data. Furthermore, the correlation is markedly improved by reconstructing the images with an object specific attenuation map obtained from the coregistered x ray CT image. We were also able to restore the 99mTc sestamibi uptake from the reconstructed images to an accuracy between 40% and 90% of the true in vitro value, depending on the selection of maximum or mean pixel values in the regions of interest.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kathrin Kalki, J. Keenan Brown, Stephen C. Blankespoor, Joseph A. Heanue, Xiang Wu, Christopher E. Cann, Bruce H. Hasegawa, Michael Chin, Carol A. Stillson, Michael W. Dae, and James M. Carver "Combined SPECT and x-ray CT medical imaging system", Proc. SPIE 2432, Medical Imaging 1995: Physics of Medical Imaging, (8 May 1995);

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