We investigated the detectability of moving, low-contrast objects in white-noise image sequences. The computer-generated, cylindrical phantoms mimicked arteries, catheters, and guide wires in medical, x-ray fluoroscopy image sequences at 16 acquisitions/s (pulsed-16) or 32 acquisitions/s (pulsed-32). We measured detectability by using a reference–test, adaptive forced-choice method whereby reference and test presentations were alternated during an experimental session to minimize effects of subject attention and accuracy criteria. In the case of the largest cylinder (diameter 0.48 deg), the highest speed (5.86 deg/s) increased absolute detectability by compared with that in the stationary case. With the smallest cylinder (diameter 0.023 deg), this motion decreased detectability by The dose savings of pulsed-16 was of that for pulsed-32, with relatively little effect of velocity or object size. In general, subjects took slightly longer to respond in the case of low-acquisition fluoroscopy. Detectability data were modeled with a nonprewhitening matched filter that included a physiological, spatiotemporal contrast sensitivity function and a suboptimal, spatiotemporal signal template with time-limited memory.
© 1998 Optical Society of AmericaFull Article | PDF Article
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