Computer simulation of image intensifier-based computed tomography detector: vascular application.
This present study reports the results of a computer simulation whose aim was to predict the low-contrast imaging performance of which a conventional x-ray image intensifier with charge coupled device (CCD) camera would be capable if incorporated into a computed tomography (CT) volume imager. A vascular imaging task was modeled in our simulation. The effects of detector noise, x-ray exposure levels, analog-to-digital conversion (ADC) precision and residual levels of detected x-ray scatter were considered. The results of this simulation indicate that the low-contrast imaging performance of an image intensifier-based CT system was most limited by the CCD detector readout noise. Given this limitation the detection of greater than about 100,000 detected photons/pixel/projection gave marginal improvement in low-contrast resolution. At these exposures 12 bit ADC precision resulted in little additional image noise. The effects of detecting scattered x rays are twofold; decreasing the signal-to-noise ratio associated with our modeled artery and introducing a cupping artifact. Based on the results from the simulation, it appears that an image intensifier-based CT system is a feasible concept from a noise viewpoint, if the anticipated imaging task is intravenous angiography.
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Radiology Department, University of Utah School of Medicine, Salt Lake City 84132.
Kruger
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D000792:Angiography / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008953:Models, Anatomic; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*